Patent Publication Number: US-2015087554-A1

Title: Polypeptide markers for the diagnosis of alzheimer&#39;s disease

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. patent application Ser. No. 11/887,603, filed Sep. 28, 2007, the contents of which are incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates to the use of the presence or absence of one or more peptide markers in a sample from a subject for the diagnosis of Alzheimer&#39;s disease and to a method for the diagnosis of Alzheimer&#39;s disease, wherein the presence or absence of the peptide marker or markers is indicative of the existence of Alzheimer&#39;s disease. 
     2. Discussion of the Background Art 
     Neuropsychiatric Diseases of Advanced Age 
     More than 7% of the aged population suffer from dementia diseases, whose most frequent cause is Alzheimer&#39;s disease, the proportion of the diseased increasing approximately exponentially from less than 2% among the 65-69 year old to more than 30% among the over 85 year old. All in all, the number of afflicted persons in Germany is currently about one million; by the year 2050, they would have increased to 2.5 million when the same prevalence is assumed. Almost 2% of the previously healthy older people are afflicted by dementia per year; in Germany, this corresponds to more than 200,000 incidences per year. Already today, one third of all people reaching the age of 65 must expect to develop a dementia in the further course of ageing. Minor symptoms of a possibly approaching dementia or the earliest stages of the disease that cannot yet be reliably diagnosed, in the form of the still not well defined disorder picture of minimal cognitive impairment (MCI), occur far more frequently than manifest dementia. From field studies, prevalence rates of from 10 to 20%, in individual cases also more than 30%, are often reported. However, the prediction of dementia is still associated with a high uncertainty in the individual case. 
     Alzheimer&#39;s Disease 
     Alzheimer&#39;s disease is also referred to as Alzheimer&#39;s or “dementia of Alzheimer&#39;s type”. The term “dementia” means a decline in mental faculties. Alzheimer&#39;s disease is characterized mainly by an initial weakness of memory, which increases in the course thereof and may lead to a total loss of power of judgment and personality. Immediately after strokes, Alzheimer&#39;s disease is the most frequent severe disorder of brain function in age. 
     With the increase of life expectancy, the disease that today bears Alzheimer&#39;s name was diagnosed more and more frequently in the developed countries. Severe impairment of memory, paranoia, insomnia and restlessness are the most important signs; however, these symptoms may also occur in other diseases singly or in combination, such as in the case of age-related dementia and stroke. 
     About one million dementia patients are living in Germany, two third thereof suffering from Alzheimer&#39;s. The risk of becoming afflicted with Alzheimer&#39;s disease increases with increasing age. According to estimations, about five percent of the population of over 65 years and about 20 percent of the population of over 80 years are concerned in the Western countries. Because females live longer than males on average, their risk of becoming afflicted with Alzheimer&#39;s disease is thus clearly higher. Although Alzheimer&#39;s disease is considered an age-related disease, rare hereditary forms of the condition may onset as early as from the thirtieth year. 
     Although Alzheimer&#39;s disease is still incurable presently, the possibilities of treatment have improved in recent years. The earlier Alzheimer&#39;s disease is recognized and treated, the better is the chance of slowing down the disease process. 
     The disease mostly begins several decades before the first symptoms occur. Depositions of protein fragments, so-called amyloids, are formed in the brain. The amyloids are distinguished into microscopically small fibers, i.e., fibrils, and spherical depositions, i.e., plaques. Evidently, these depositions prevent nerve cells from communicating with each other. In the course of time, the nerve cells then die off in those regions of the brain that are involved in the development of memory, speech and reasoning powers. 
     Only in exceptional cases, the disease is triggered by gene alterations and breaks out in younger ages already. This may happen, for example, when the genetic information of the amyloid precursor protein (APP) is damaged. Harmful cleavage products of APP, which form the most important component of plaques, are increasingly formed. Alterations in other genes, the presenilins, have similar effects. They increase the activity of enzymes that degrade APP, and therefore also accelerate the formation of lumps in the brain. 
     The most important genetic risk factor is a molecule (ApoE) which is involved in the transport of cholesterol in the blood. The genetic information for ApoE occurs in three variants. One variant (ApoE4) increases the risk of disease by four to five times on statistical average, another variant (ApoE2) lowers the risk. 
     Diagnosis 
     Although simple tests are reported from time to time, Alzheimer&#39;s disease can be established with absolute certainty only after a patient&#39;s death when the typical depositions can be found in the brain. In practice, it is important to make as certain as possible a diagnosis as early as possible. 
     Typical symptoms of Alzheimer&#39;s disease are:
         impairment of short-term memory   difficulty in reasoning   speech disorders   depressions   restricted power of judgment   delusions   changes of personality       

     A deterioration of the short-term memory as a first symptom mostly can be observed at the age of 60 to 70 years already. The power of concentration and cognitive power decline, speech disorders occur, tiredness increases. The symptoms of depression frequently occur in the initial phase. They are accompanied by changes of behavior, such as confusion, anxiety, restlessness and aggressiveness. They can no longer cope with everyday skills, such as dressing, preparing meals or shopping, and finally they lose control of their physical functions. In the final stage, the patients often become silent, bedridden and completely depend on other persons&#39; help. 
     As already described, there is no functioning early detection and no reliable diagnosis for Alzheimer&#39;s. Thus, there has been a need to find a process and method for a diagnosis of Alzheimer&#39;s disease that is as little as possible invasive, quick and inexpensive. 
     In Electrophoresis 26 (2005), 1476-1487, Wittke et al. describe the use of markers in human urine in CE-MS coupling and their suitability in principle for the diagnosis of Alzheimer&#39;s disease. From today&#39;s point of view, it is seen that the markers found therein have only a small significance. 
     The object of the present disclosure is to overcome at least some of the mentioned drawbacks of the prior art, especially to provide markers that have an improved significance over those of the prior art. 
     SUMMARY OF THE DISCLOSURE 
     Surprisingly, it has now been found that particular peptide markers in combination in a sample from a subject can be used for the diagnosis of Alzheimer&#39;s disease. Consequently, the present disclosure relates to the use of the presence or absence of at least three polypeptide markers in a sample from a subject for the diagnosis of Alzheimer&#39;s disease, wherein said polypeptide marker is selected from polypeptide marker Nos. 1 to 279 as characterized by the molecular masses and migration times as stated in Table 1. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Polypeptide markers for the diagnosis of Alzheimer&#39;s disease 
               
               
                 and their molecular masses and migration times: 
               
            
           
           
               
               
               
            
               
                   
                   
                 Migration 
               
               
                   
                 Mass 
                 time 
               
               
                 No. 
                 [g/mol] 
                 [min] 
               
               
                   
               
            
           
           
               
               
               
            
               
                 1 
                 1073.35 
                 34.96 
               
               
                 2 
                 1073.35 
                 35.9 
               
               
                 3 
                 1110.31 
                 37.67 
               
               
                 4 
                 1111.3 
                 34.97 
               
               
                 5 
                 1196.36 
                 36.37 
               
               
                 6 
                 1265.63 
                 27.22 
               
               
                 7 
                 1322.44 
                 36.2 
               
               
                 8 
                 1387.07 
                 20.42 
               
               
                 9 
                 1390.49 
                 36.26 
               
               
                 10 
                 1423.57 
                 29.85 
               
               
                 11 
                 1453.55 
                 30.47 
               
               
                 12 
                 1490.43 
                 35.48 
               
               
                 13 
                 1494.62 
                 30.23 
               
               
                 14 
                 1819.86 
                 23.51 
               
               
                 15 
                 1927.02 
                 21 
               
               
                 16 
                 2128.97 
                 26.03 
               
               
                 17 
                 2214.22 
                 26.48 
               
               
                 18 
                 2313.26 
                 30.32 
               
               
                 19 
                 2423.19 
                 27.03 
               
               
                 20 
                 2428.11 
                 27.16 
               
               
                 21 
                 2521.33 
                 27.86 
               
               
                 22 
                 2644.31 
                 21.1 
               
               
                 23 
                 2706.37 
                 28.3 
               
               
                 24 
                 3068.46 
                 30.03 
               
               
                 25 
                 3079.61 
                 37.02 
               
               
                 26 
                 3153.38 
                 35.65 
               
               
                 27 
                 3229.79 
                 25.02 
               
               
                 28 
                 3438.77 
                 23.49 
               
               
                 29 
                 3481.8 
                 30.62 
               
               
                 30 
                 3567.61 
                 23.88 
               
               
                 31 
                 3685.85 
                 25.47 
               
               
                 32 
                 3921.84 
                 29.49 
               
               
                 33 
                 4036.3 
                 24.92 
               
               
                 34 
                 4038.22 
                 20.53 
               
               
                 35 
                 4093.96 
                 21.04 
               
               
                 36 
                 4145.22 
                 24.51 
               
               
                 37 
                 4372.3 
                 19.37 
               
               
                 38 
                 4377.95 
                 30.81 
               
               
                 39 
                 4496.98 
                 19.35 
               
               
                 40 
                 4516 
                 19.37 
               
               
                 41 
                 4540.4 
                 22 
               
               
                 42 
                 4586.98 
                 19.38 
               
               
                 43 
                 4596.23 
                 19.6 
               
               
                 44 
                 4810.95 
                 19.77 
               
               
                 45 
                 5227.91 
                 25.08 
               
               
                 46 
                 5582.16 
                 24.3 
               
               
                 47 
                 6402.73 
                 22.3 
               
               
                 48 
                 7749.32 
                 19.97 
               
               
                 49 
                 7760.02 
                 28.72 
               
               
                 50 
                 10671.25 
                 28.92 
               
               
                 51 
                 824.48 
                 19.92 
               
               
                 52 
                 840.49 
                 19.92 
               
               
                 53 
                 846.38 
                 25.96 
               
               
                 54 
                 897.41 
                 25.86 
               
               
                 55 
                 911.3 
                 34.1 
               
               
                 56 
                 950.57 
                 24.13 
               
               
                 57 
                 973.26 
                 35.47 
               
               
                 58 
                 984.45 
                 26.32 
               
               
                 59 
                 988.57 
                 35.65 
               
               
                 60 
                 1013.43 
                 25.18 
               
               
                 61 
                 1016.3 
                 35.53 
               
               
                 62 
                 1041.58 
                 36.79 
               
               
                 63 
                 1053.52 
                 25.25 
               
               
                 64 
                 1055.61 
                 25.7 
               
               
                 65 
                 1082.55 
                 23.75 
               
               
                 66 
                 1082.65 
                 26.15 
               
               
                 67 
                 1083.5 
                 27.14 
               
               
                 68 
                 1083.55 
                 25.61 
               
               
                 69 
                 1085.63 
                 36.39 
               
               
                 70 
                 1094.61 
                 25.99 
               
               
                 71 
                 1130.37 
                 35.19 
               
               
                 72 
                 1130.63 
                 27.07 
               
               
                 73 
                 1135.56 
                 27.03 
               
               
                 74 
                 1150.61 
                 26.55 
               
               
                 75 
                 1158.62 
                 27.02 
               
               
                 76 
                 1183.66 
                 27.49 
               
               
                 77 
                 1186.56 
                 27.21 
               
               
                 78 
                 1217.56 
                 21.8 
               
               
                 79 
                 1229.62 
                 27.38 
               
               
                 80 
                 1250.61 
                 27.59 
               
               
                 81 
                 1276.43 
                 35.7 
               
               
                 82 
                 1283.4 
                 35.91 
               
               
                 83 
                 1300.67 
                 29.7 
               
               
                 84 
                 1306.74 
                 22.16 
               
               
                 85 
                 1333.44 
                 35.93 
               
               
                 86 
                 1342.44 
                 35.43 
               
               
                 87 
                 1347.71 
                 28.94 
               
               
                 88 
                 1349.67 
                 28.25 
               
               
                 89 
                 1360.67 
                 28.06 
               
               
                 90 
                 1386.68 
                 28.62 
               
               
                 91 
                 1388.74 
                 27.97 
               
               
                 92 
                 1399.44 
                 36.06 
               
               
                 93 
                 1404.73 
                 29.49 
               
               
                 94 
                 1409.63 
                 22.11 
               
               
                 95 
                 1449.7 
                 22.04 
               
               
                 96 
                 1451.72 
                 28.84 
               
               
                 97 
                 1464.7 
                 30.57 
               
               
                 99 
                 1475.77 
                 30.05 
               
               
                 100 
                 1499.74 
                 29.89 
               
               
                 101 
                 1519.76 
                 31.87 
               
               
                 102 
                 1535.74 
                 30 
               
               
                 103 
                 1542.78 
                 23.24 
               
               
                 104 
                 1550.67 
                 27.47 
               
               
                 105 
                 1552.61 
                 30.78 
               
               
                 106 
                 1590.81 
                 32.46 
               
               
                 107 
                 1596.83 
                 30.32 
               
               
                 108 
                 1614.84 
                 31.54 
               
               
                 109 
                 1623.65 
                 31.1 
               
               
                 110 
                 1628.8 
                 20.75 
               
               
                 111 
                 1636.79 
                 22.71 
               
               
                 112 
                 1659.81 
                 27.41 
               
               
                 113 
                 1692.91 
                 31.38 
               
               
                 114 
                 1703.89 
                 33.01 
               
               
                 115 
                 1727.92 
                 32.13 
               
               
                 116 
                 1732.88 
                 31.36 
               
               
                 117 
                 1738.68 
                 32.16 
               
               
                 118 
                 1741.83 
                 30.56 
               
               
                 119 
                 1756.89 
                 19.81 
               
               
                 120 
                 1771.97 
                 30.02 
               
               
                 121 
                 1800.02 
                 25 
               
               
                 122 
                 1816.98 
                 33.53 
               
               
                 123 
                 1820.06 
                 32.23 
               
               
                 124 
                 1841.77 
                 36.26 
               
               
                 125 
                 1849.68 
                 18.31 
               
               
                 126 
                 1850.96 
                 31.97 
               
               
                 127 
                 1867.72 
                 33.07 
               
               
                 128 
                 1869.92 
                 31.28 
               
               
                 129 
                 1873 
                 21.26 
               
               
                 130 
                 1900.07 
                 24.19 
               
               
                 131 
                 1914.07 
                 25.67 
               
               
                 132 
                 1915.72 
                 34.24 
               
               
                 133 
                 1917.03 
                 24.99 
               
               
                 134 
                 1955.95 
                 27.81 
               
               
                 135 
                 2021.11 
                 21.85 
               
               
                 136 
                 2041.99 
                 32.56 
               
               
                 137 
                 2053.18 
                 20.54 
               
               
                 138 
                 2072.15 
                 27.04 
               
               
                 139 
                 2077.07 
                 25.44 
               
               
                 140 
                 2085.12 
                 33.75 
               
               
                 141 
                 2140.12 
                 20.56 
               
               
                 142 
                 2166.09 
                 27.84 
               
               
                 143 
                 2168.66 
                 34.88 
               
               
                 144 
                 2179.03 
                 25.31 
               
               
                 145 
                 2278.11 
                 26.17 
               
               
                 146 
                 2283.18 
                 26.31 
               
               
                 147 
                 2314.3 
                 22.71 
               
               
                 148 
                 2320.43 
                 23.21 
               
               
                 149 
                 2327.24 
                 34.9 
               
               
                 150 
                 2341.12 
                 26.74 
               
               
                 151 
                 2343.24 
                 34.95 
               
               
                 152 
                 2368.24 
                 21.24 
               
               
                 153 
                 2377.25 
                 28.07 
               
               
                 154 
                 2390.26 
                 27.33 
               
               
                 155 
                 2392.73 
                 35.48 
               
               
                 156 
                 2409.28 
                 27.64 
               
               
                 157 
                 2410.3 
                 30.62 
               
               
                 158 
                 2448.39 
                 21.07 
               
               
                 159 
                 2475.21 
                 27.09 
               
               
                 160 
                 2475.27 
                 24.74 
               
               
                 161 
                 2486.04 
                 35.76 
               
               
                 162 
                 2500.33 
                 19.99 
               
               
                 163 
                 2521.36 
                 19.26 
               
               
                 164 
                 2522.35 
                 27.9 
               
               
                 165 
                 2527.42 
                 19.79 
               
               
                 166 
                 2549.29 
                 27.66 
               
               
                 167 
                 2584.37 
                 35.6 
               
               
                 168 
                 2684.32 
                 21.38 
               
               
                 169 
                 2698.41 
                 22.52 
               
               
                 170 
                 2799.17 
                 25.07 
               
               
                 171 
                 2816.31 
                 28.74 
               
               
                 172 
                 2851.42 
                 27.7 
               
               
                 173 
                 2923.51 
                 36.73 
               
               
                 174 
                 2982.72 
                 19.97 
               
               
                 175 
                 3019.54 
                 24.72 
               
               
                 176 
                 3173.68 
                 22.95 
               
               
                 177 
                 3192.67 
                 37.66 
               
               
                 178 
                 3215.61 
                 28.53 
               
               
                 179 
                 3218.4 
                 30.31 
               
               
                 180 
                 3221.59 
                 22.7 
               
               
                 181 
                 3279.66 
                 25.32 
               
               
                 182 
                 3282.34 
                 36.05 
               
               
                 183 
                 3298.42 
                 36.17 
               
               
                 184 
                 3302.68 
                 23.31 
               
               
                 185 
                 3324.7 
                 21.62 
               
               
                 186 
                 3386.77 
                 22.21 
               
               
                 187 
                 3401.73 
                 23.48 
               
               
                 188 
                 3408.76 
                 26.04 
               
               
                 189 
                 3462.68 
                 21.25 
               
               
                 190 
                 3466.75 
                 23.9 
               
               
                 191 
                 3524.8 
                 31.72 
               
               
                 192 
                 3529.84 
                 23.7 
               
               
                 193 
                 3595.77 
                 23.89 
               
               
                 194 
                 3605.4 
                 21.53 
               
               
                 195 
                 3614.82 
                 22.01 
               
               
                 196 
                 3644.79 
                 29.39 
               
               
                 197 
                 3645.25 
                 26.69 
               
               
                 198 
                 3650.74 
                 19.9 
               
               
                 199 
                 3672.71 
                 21.9 
               
               
                 200 
                 3677.74 
                 24.3 
               
               
                 201 
                 3685.86 
                 22.21 
               
               
                 202 
                 3687.78 
                 20.58 
               
               
                 203 
                 3693.93 
                 27.15 
               
               
                 204 
                 3741.63 
                 20.1 
               
               
                 205 
                 3768.77 
                 31.84 
               
               
                 206 
                 3782.94 
                 22.68 
               
               
                 207 
                 3788.04 
                 25.24 
               
               
                 208 
                 3792.76 
                 27.25 
               
               
                 209 
                 3819.82 
                 32.74 
               
               
                 210 
                 3881.87 
                 24.56 
               
               
                 211 
                 3903.08 
                 25.71 
               
               
                 212 
                 3905.8 
                 27.72 
               
               
                 213 
                 3929.73 
                 23.07 
               
               
                 214 
                 3934.76 
                 24.02 
               
               
                 215 
                 3951.07 
                 22.77 
               
               
                 216 
                 4005.54 
                 22.57 
               
               
                 217 
                 4087.12 
                 26.92 
               
               
                 218 
                 4112.78 
                 24.46 
               
               
                 219 
                 4131.68 
                 22.54 
               
               
                 220 
                 4164.86 
                 25.11 
               
               
                 221 
                 4192.99 
                 34.95 
               
               
                 222 
                 4203.13 
                 26.14 
               
               
                 223 
                 4218.31 
                 20.6 
               
               
                 224 
                 4232.32 
                 32.35 
               
               
                 225 
                 4250 
                 27.68 
               
               
                 226 
                 4278 
                 25.3 
               
               
                 227 
                 4301.93 
                 21.26 
               
               
                 228 
                 4307.09 
                 31.58 
               
               
                 229 
                 4349.06 
                 28.17 
               
               
                 230 
                 4384.07 
                 19.8 
               
               
                 231 
                 4428.79 
                 32.86 
               
               
                 232 
                 4464.64 
                 21.54 
               
               
                 233 
                 4468.61 
                 23.47 
               
               
                 234 
                 4510.97 
                 28.56 
               
               
                 235 
                 4548.03 
                 25.95 
               
               
                 236 
                 4562 
                 29.31 
               
               
                 237 
                 4562 
                 29.31 
               
               
                 238 
                 4564.18 
                 26.01 
               
               
                 239 
                 4583.84 
                 24.2 
               
               
                 240 
                 4637.81 
                 27.82 
               
               
                 241 
                 4730.71 
                 19.63 
               
               
                 242 
                 4749.41 
                 21.81 
               
               
                 243 
                 4750.06 
                 19.53 
               
               
                 244 
                 4890.59 
                 23.27 
               
               
                 245 
                 4933.64 
                 20.57 
               
               
                 246 
                 4986.98 
                 21.35 
               
               
                 247 
                 5039.63 
                 25.68 
               
               
                 248 
                 5042.1 
                 24.31 
               
               
                 249 
                 5060.4 
                 20.09 
               
               
                 250 
                 5110.36 
                 25.28 
               
               
                 251 
                 5122.44 
                 20.75 
               
               
                 252 
                 5157.79 
                 34.26 
               
               
                 253 
                 5181.63 
                 25.36 
               
               
                 254 
                 5258.56 
                 22.09 
               
               
                 255 
                 5439.46 
                 25.41 
               
               
                 256 
                 5495.33 
                 31.72 
               
               
                 257 
                 5660.6 
                 31.55 
               
               
                 258 
                 5745.2 
                 19.72 
               
               
                 259 
                 5891.27 
                 24.16 
               
               
                 260 
                 6224.17 
                 25.27 
               
               
                 261 
                 6327.46 
                 22.03 
               
               
                 262 
                 6498.75 
                 20.1 
               
               
                 263 
                 6611.97 
                 28.44 
               
               
                 264 
                 6617.76 
                 24.03 
               
               
                 265 
                 6813.98 
                 23.14 
               
               
                 266 
                 6881.81 
                 21.72 
               
               
                 267 
                 6893.8 
                 24.57 
               
               
                 268 
                 6985.31 
                 21.87 
               
               
                 269 
                 7026.99 
                 22.02 
               
               
                 270 
                 7049.04 
                 22.79 
               
               
                 271 
                 7106.83 
                 23 
               
               
                 272 
                 7142.49 
                 21.32 
               
               
                 273 
                 7210.86 
                 22.94 
               
               
                 274 
                 8176.16 
                 19.47 
               
               
                 275 
                 8186.93 
                 20.72 
               
               
                 276 
                 8289.28 
                 19.39 
               
               
                 277 
                 9724.01 
                 25.64 
               
               
                 278 
                 12529 
                 20.64 
               
               
                 279 
                 14557.83 
                 19.21 
               
               
                   
               
            
           
         
       
     
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  is a graph plotting sensitivity vs. 100-specificity for biomarkers with the IDs 108317 (ID paper 356), 108983 (ID paper 362), ID 128206 (ID paper 472), ID 131316 (ID paper 490), ID 131401 (ID paper 491) and ID 136537 (ID paper 515); 
         FIG. 1   b  graph plotting sensitivity vs. 100-specificity for biomarkers with the IDs 49693 (ID paper 51),  66564  (ID paper 111), ID 75674 (ID paper 142), ID 89174 (ID paper 208); 
         FIG. 2   a  and  b  are graphs plotting sensitivity vs. 100-specificity for markers according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     With the present disclosure, it is possible to diagnose Alzheimer&#39;s disease very early and reliably. Thus, the disease can be cured at an early stage. The disclosure further enables an inexpensive, quick and reliable diagnosis with only minimal-invasive operations. 
     The migration time is determined by capillary electrophoresis (CE), for example, as set forth in the Example under item 2. In this Example, a glass capillary of 90 cm in length and with an inner diameter (ID) of 50 μm and an outer diameter (OD) of 360 μm is operated at an applied voltage of 30 kV. As the mobile solvent, 30% methanol, 0.5% formic acid in water is used. 
     It is known that the CE migration times may vary. Nevertheless, the order in which the polypeptide markers are eluted is typically the same under the stated conditions for any CE system employed. In order to balance any differences in the migration time that may nevertheless occur, the system can be normalized using standards for which the migration times are exactly known. These standards may be, for example, the polypeptides stated in the Examples (see the Example, item 3). 
     The characterization of the polypeptides shown in Tables 1 to 3 was determined by means of capillary electrophoresis-mass spectrometry (CE-MS), a method which has been described in detail, for example, by Neuhoff et al. (Rapid communications in mass spectrometry, 2004, Vol. 20, pages 149-156). The variation of the molecular masses between individual measurements or between different mass spectrometers is relatively small when the calibration is exact, typically within a range of ±0.1%, preferably within a range of ±0.05%. 
     The polypeptide markers according to the disclosure are proteins or peptides or degradation products of proteins or peptides. They may be chemically modified, for example, by posttranslational modifications, such as glycosylation, phosphorylation, alkylation or disulfide bridges, or by other reactions, for example, within the scope of degradation. In addition, the polypeptide markers may also be chemically altered, for example, oxidized, during the purification of the samples. 
     Proceeding from the parameters that determine the polypeptide markers (molecular weight and migration time), it is possible to identify the sequence of the corresponding polypeptides by methods known in the prior art. 
     The polypeptides according to the disclosure (see Tables 1 to 3) are used to diagnose Alzheimer&#39;s disease. “Diagnosis” means the process of knowledge gaining by assigning symptoms or phenomena to a disease or injury. In the present case, the existence of Alzheimer&#39;s disease is concluded from the presence or absence of particular polypeptide markers. Thus, the polypeptide markers according to the disclosure are determined in a sample from a subject, wherein its presence or absence allows to conclude the existence of Alzheimer&#39;s disease. The presence or absence of a polypeptide marker can be measured by any method known in the prior art. Methods which may be used are exemplified below. 
     A polypeptide marker is considered present if its measured value is at least as high as its threshold value. If the measured value is lower, then the polypeptide marker is considered absent. The threshold value can be determined either by the sensitivity of the measuring method (detection limit) or defined from experience. 
     In the context of the present disclosure, the threshold value is considered to be exceeded preferably if the measured value of the sample for a certain molecular mass is at least twice as high as that of a blank sample (for example, only buffer or solvent). 
     The polypeptide marker or markers is/are used in such a way that its/their presence or absence is measured, wherein the presence or absence is indicative of Alzheimer&#39;s disease. Table 2 shows polypeptide markers which are typically present in patients with Alzheimer&#39;s disease (ill), such as polypeptide markers No. 1 to 50, but absent or rarely present in subjects with no Alzheimer&#39;s disease (control). In addition, there are polypeptide markers which are present in subjects with no Alzheimer&#39;s disease, but are less frequently or not at all present in subjects with Alzheimer&#39;s disease, for example, polypeptide markers No. 43 or 44. 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Polypeptide markers for the diagnosis of Alzheimer&#39;s disease, their 
               
               
                 molecular masses and migration times as well as their presence and 
               
               
                 absence in the individual groups as frequency per group 
               
               
                 (1 = 100%, 0 = 0%) in the group of patients suffering 
               
               
                 from Alzheimer&#39;s disease and the control group 
               
               
                 (sample processing and measurement as described in the Example). 
               
            
           
           
               
               
            
               
                   
                 Frequency per group 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                 Mass 
                 Migration time 
                 Frequency 
                 Alzheimer&#39;s 
                   
               
               
                 No. 
                 [g/mol] 
                 [min] 
                 difference 
                 dementia 
                 Controls 
               
               
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 1 
                 1073.35 
                 34.96 
                 0.45 
                 0.45 
                 0 
               
               
                 2 
                 1073.35 
                 35.9 
                 −0.48 
                 0.46 
                 0.94 
               
               
                 3 
                 1110.31 
                 37.67 
                 −0.44 
                 0 
                 0.44 
               
               
                 4 
                 1111.3 
                 34.97 
                 −0.41 
                 0.27 
                 0.69 
               
               
                 5 
                 1196.36 
                 36.37 
                 −0.44 
                 0.31 
                 0.75 
               
               
                 6 
                 1265.63 
                 27.22 
                 0.41 
                 0.66 
                 0.25 
               
               
                 7 
                 1322.44 
                 36.2 
                 0.44 
                 0.75 
                 0.31 
               
               
                 8 
                 1387.07 
                 20.42 
                 −0.41 
                 0.09 
                 0.5 
               
               
                 9 
                 1390.49 
                 36.26 
                 0.42 
                 0.55 
                 0.13 
               
               
                 10 
                 1423.57 
                 29.85 
                 0.48 
                 0.79 
                 0.31 
               
               
                 11 
                 1453.55 
                 30.47 
                 0.44 
                 0.63 
                 0.19 
               
               
                 12 
                 1490.43 
                 35.48 
                 0.42 
                 0.79 
                 0.38 
               
               
                 13 
                 1494.62 
                 30.23 
                 0.5 
                 0.75 
                 0.25 
               
               
                 14 
                 1819.86 
                 23.51 
                 −0.48 
                 0.27 
                 0.75 
               
               
                 15 
                 1927.02 
                 21 
                 0.48 
                 0.67 
                 0.19 
               
               
                 16 
                 2128.97 
                 26.03 
                 0.46 
                 0.96 
                 0.5 
               
               
                 17 
                 2214.22 
                 26.48 
                 0.52 
                 0.83 
                 0.31 
               
               
                 18 
                 2313.26 
                 30.32 
                 0.48 
                 0.67 
                 0.19 
               
               
                 19 
                 2423.19 
                 27.03 
                 0.41 
                 0.6 
                 0.19 
               
               
                 20 
                 2428.11 
                 27.16 
                 −0.45 
                 0.36 
                 0.81 
               
               
                 21 
                 2521.33 
                 27.86 
                 −0.44 
                 0 
                 0.44 
               
               
                 22 
                 2644.31 
                 21.1 
                 0.45 
                 0.89 
                 0.44 
               
               
                 23 
                 2706.37 
                 28.3 
                 0.46 
                 0.71 
                 0.25 
               
               
                 24 
                 3068.46 
                 30.03 
                 0.46 
                 0.77 
                 0.31 
               
               
                 25 
                 3079.61 
                 37.02 
                 −0.42 
                 0.46 
                 0.88 
               
               
                 26 
                 3153.38 
                 35.65 
                 0.46 
                 0.71 
                 0.25 
               
               
                 27 
                 3229.79 
                 25.02 
                 −0.44 
                 0 
                 0.44 
               
               
                 28 
                 3438.77 
                 23.49 
                 0.44 
                 0.75 
                 0.31 
               
               
                 29 
                 3481.8 
                 30.62 
                 0.45 
                 0.89 
                 0.44 
               
               
                 30 
                 3567.61 
                 23.88 
                 −0.44 
                 0.18 
                 0.63 
               
               
                 31 
                 3685.85 
                 25.47 
                 −0.44 
                 0.18 
                 0.63 
               
               
                 32 
                 3921.84 
                 29.49 
                 −0.41 
                 0.09 
                 0.5 
               
               
                 33 
                 4036.3 
                 24.92 
                 0.5 
                 0.69 
                 0.19 
               
               
                 34 
                 4038.22 
                 20.53 
                 −0.63 
                 0 
                 0.63 
               
               
                 35 
                 4093.96 
                 21.04 
                 0.5 
                 0.63 
                 0.13 
               
               
                 36 
                 4145.22 
                 24.51 
                 0.42 
                 0.42 
                 0 
               
               
                 37 
                 4372.3 
                 19.37 
                 −0.44 
                 0.18 
                 0.63 
               
               
                 38 
                 4377.95 
                 30.81 
                 0.5 
                 0.63 
                 0.13 
               
               
                 39 
                 4496.98 
                 19.35 
                 −0.41 
                 0.09 
                 0.5 
               
               
                 40 
                 4516 
                 19.37 
                 −0.45 
                 0.36 
                 0.81 
               
               
                 41 
                 4540.4 
                 22 
                 −0.41 
                 0.09 
                 0.5 
               
               
                 42 
                 4586.98 
                 19.38 
                 −0.41 
                 0.27 
                 0.69 
               
               
                 43 
                 4596.23 
                 19.6 
                 −0.47 
                 0.09 
                 0.56 
               
               
                 44 
                 4810.95 
                 19.77 
                 −0.44 
                 0 
                 0.44 
               
               
                 45 
                 5227.91 
                 25.08 
                 0.54 
                 0.73 
                 0.19 
               
               
                 46 
                 5582.16 
                 24.3 
                 0.4 
                 0.4 
                 0 
               
               
                 47 
                 6402.73 
                 22.3 
                 0.44 
                 0.63 
                 0.19 
               
               
                 48 
                 7749.32 
                 19.97 
                 −0.41 
                 0.09 
                 0.5 
               
               
                 49 
                 7760.02 
                 28.72 
                 0.46 
                 0.71 
                 0.25 
               
               
                 50 
                 10671.25 
                 28.92 
                 0.48 
                 0.67 
                 0.19 
               
               
                   
               
            
           
         
       
     
     In addition or also alternatively to the frequency markers (determination of presence or absence), the amplitude markers as stated in Table 3 may also be used for the diagnosis of Alzheimer&#39;s disease (Nos. 51-279). Amplitude markers are used in such a way that the presence or absence is not critical, but the height of the signal (the amplitude) decides if the signal is present in both groups. In Table 3, the mean amplitudes of the corresponding signals (characterized by mass and migration time) averaged over all samples measured are stated. To achieve comparability between differently concentrated samples or different measuring methods, all peptide signals of a sample are normalized to a total amplitude of 1 million counts. Therefore, the respective mean amplitudes of the individual markers are stated as parts per million (ppm). All groups employed consist of at least 15 individual patient or control samples in order to obtain a reliable mean amplitude. The decision for a diagnosis (Alzheimer&#39;s or not) is made as a function of how high the amplitude of the respective polypeptide markers in the patient sample is in comparison with the mean amplitudes in the control groups or the Alzheimer group. If the mean amplitudes rather correspond to the mean amplitudes of the Alzheimer group, the existence of Alzheimer&#39;s disease is to be considered, and if it rather corresponds to the mean amplitudes of the control group, the non-existence of Alzheimer&#39;s disease is to be considered. A more exact definition shall be given by means of marker No. 130 (Table 3). The mean amplitude of the marker is significantly increased in Alzheimer&#39;s disease (920 ppm vs. 373 ppm in the control group). Now, if the value for this marker in a patient sample is from 0 to 373 ppm or exceeds this range by a maximum of 20%, i.e., from 0 to 448 ppm, then this sample belongs to the control group. If the value is around 920 ppm or up to 20% below, or higher, i.e., between 736 and very high values, the existence of Alzheimer&#39;s disease is to be considered. The smaller the distance between the amplitudes of the control group and the Alzheimer group, the closer a value that lies between the two reference values has to be to one of the reference values. 
     One possibility is to subdivide the range between the mean amplitudes into three portions. If the value is in the lower third, this is indicative of the lower value; if the value is in the upper third, this is indicative of the upper value. If it is in the middle third, a definite statement about this marker is not possible. 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Amplitude markers 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                 mean amplitude per 
                   
               
               
                   
                 Mass 
                 Migration 
                 group 
               
            
           
           
               
               
               
               
               
            
               
                 No. 
                 [g/mol] 
                 time [min] 
                 Alzheimer 
                 Controls 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 51 
                 824.48 
                 19.92 
                 568.85 
                 501.97 
               
               
                 52 
                 840.49 
                 19.92 
                 810.27 
                 593.64 
               
               
                 53 
                 846.38 
                 25.96 
                 100.62 
                 122.25 
               
               
                 54 
                 897.41 
                 25.86 
                 81.54 
                 48.26 
               
               
                 55 
                 911.3 
                 34.1 
                 242.62 
                 247.96 
               
               
                 56 
                 950.57 
                 24.13 
                 78.07 
                 67.87 
               
               
                 57 
                 973.26 
                 35.47 
                 179.96 
                 150.04 
               
               
                 58 
                 984.45 
                 26.32 
                 110.69 
                 132.44 
               
               
                 59 
                 988.57 
                 35.65 
                 211.75 
                 188.31 
               
               
                 60 
                 1013.43 
                 25.18 
                 175.63 
                 104.85 
               
               
                 61 
                 1016.3 
                 35.53 
                 909.17 
                 810.15 
               
               
                 62 
                 1041.58 
                 36.79 
                 86.97 
                 139.71 
               
               
                 63 
                 1053.52 
                 25.25 
                 87.43 
                 46.52 
               
               
                 64 
                 1055.61 
                 25.7 
                 277.17 
                 465.99 
               
               
                 65 
                 1082.55 
                 23.75 
                 78.89 
                 50.53 
               
               
                 66 
                 1082.65 
                 26.15 
                 112.48 
                 104.55 
               
               
                 67 
                 1083.5 
                 27.14 
                 118.51 
                 108.08 
               
               
                 68 
                 1083.55 
                 25.61 
                 271.44 
                 164.33 
               
               
                 69 
                 1085.63 
                 36.39 
                 140.8 
                 145.98 
               
               
                 70 
                 1094.61 
                 25.99 
                 460.11 
                 418.75 
               
               
                 71 
                 1130.37 
                 35.19 
                 670.41 
                 372.37 
               
               
                 72 
                 1130.63 
                 27.07 
                 115.03 
                 78.26 
               
               
                 73 
                 1135.56 
                 27.03 
                 60.46 
                 58.13 
               
               
                 74 
                 1150.61 
                 26.55 
                 80.41 
                 45.34 
               
               
                 75 
                 1158.62 
                 27.02 
                 68.79 
                 40.98 
               
               
                 76 
                 1183.66 
                 27.49 
                 110.3 
                 73.65 
               
               
                 77 
                 1186.56 
                 27.21 
                 315.86 
                 221.73 
               
               
                 78 
                 1217.56 
                 21.8 
                 90.54 
                 80.33 
               
               
                 79 
                 1229.62 
                 27.38 
                 99.75 
                 62.81 
               
               
                 80 
                 1250.61 
                 27.59 
                 455.17 
                 151.8 
               
               
                 81 
                 1276.43 
                 35.7 
                 1739.68 
                 1000.12 
               
               
                 82 
                 1283.4 
                 35.91 
                 104.76 
                 53 
               
               
                 83 
                 1300.67 
                 29.7 
                 120.17 
                 58.65 
               
               
                 84 
                 1306.74 
                 22.16 
                 552.66 
                 320.23 
               
               
                 85 
                 1333.44 
                 35.93 
                 268.17 
                 204.63 
               
               
                 86 
                 1342.44 
                 35.43 
                 275.61 
                 325.49 
               
               
                 87 
                 1347.71 
                 28.94 
                 83.29 
                 67.88 
               
               
                 88 
                 1349.67 
                 28.25 
                 363.22 
                 580.39 
               
               
                 89 
                 1360.67 
                 28.06 
                 90.7 
                 94.56 
               
               
                 90 
                 1386.68 
                 28.62 
                 366.31 
                 404.69 
               
               
                 91 
                 1388.74 
                 27.97 
                 319.52 
                 394.09 
               
               
                 92 
                 1399.44 
                 36.06 
                 179.15 
                 82.16 
               
               
                 93 
                 1404.73 
                 29.49 
                 165.77 
                 108.43 
               
               
                 94 
                 1409.63 
                 22.11 
                 288.37 
                 317.52 
               
               
                 95 
                 1449.7 
                 22.04 
                 77.35 
                 102.04 
               
               
                 96 
                 1451.72 
                 28.84 
                 111.94 
                 52.91 
               
               
                 97 
                 1464.7 
                 30.57 
                 1169.16 
                 1453.9 
               
               
                 98 
                 1464.7 
                 30.57 
                 1346.04 
                 1453.9 
               
               
                 99 
                 1475.77 
                 30.05 
                 216.71 
                 146.11 
               
               
                 100 
                 1499.74 
                 29.89 
                 104.53 
                 57.36 
               
               
                 101 
                 1519.76 
                 31.87 
                 392.54 
                 271.33 
               
               
                 102 
                 1535.74 
                 30 
                 2366.44 
                 3661.09 
               
               
                 103 
                 1542.78 
                 23.24 
                 713.91 
                 533.83 
               
               
                 104 
                 1550.67 
                 27.47 
                 576.53 
                 637.58 
               
               
                 105 
                 1552.61 
                 30.78 
                 176.95 
                 110.5 
               
               
                 106 
                 1590.81 
                 32.46 
                 1491.15 
                 1260.68 
               
               
                 107 
                 1596.83 
                 30.32 
                 873.36 
                 577.23 
               
               
                 108 
                 1614.84 
                 31.54 
                 688.7 
                 410.65 
               
               
                 109 
                 1623.65 
                 31.1 
                 697.2 
                 364.52 
               
               
                 110 
                 1628.8 
                 20.75 
                 304.52 
                 326.72 
               
               
                 111 
                 1636.79 
                 22.71 
                 1006.43 
                 814.9 
               
               
                 112 
                 1659.81 
                 27.41 
                 589.62 
                 358.41 
               
               
                 113 
                 1692.91 
                 31.38 
                 127.4 
                 95.57 
               
               
                 114 
                 1703.89 
                 33.01 
                 287.84 
                 258.89 
               
               
                 115 
                 1727.92 
                 32.13 
                 552.58 
                 276.12 
               
               
                 116 
                 1732.88 
                 31.36 
                 596.19 
                 543.08 
               
               
                 117 
                 1738.68 
                 32.16 
                 92.84 
                 40.42 
               
               
                 118 
                 1741.83 
                 30.56 
                 114.01 
                 84.13 
               
               
                 119 
                 1756.89 
                 19.81 
                 176.68 
                 85.89 
               
               
                 120 
                 1771.97 
                 30.02 
                 328.73 
                 214.56 
               
               
                 121 
                 1800.02 
                 25 
                 516.9 
                 674.37 
               
               
                 122 
                 1816.98 
                 33.53 
                 395.82 
                 180.33 
               
               
                 123 
                 1820.06 
                 32.23 
                 107.09 
                 76.57 
               
               
                 124 
                 1841.77 
                 36.26 
                 847.46 
                 1396.48 
               
               
                 125 
                 1849.68 
                 18.31 
                 405.84 
                 688.91 
               
               
                 126 
                 1850.96 
                 31.97 
                 116.29 
                 133.34 
               
               
                 127 
                 1867.72 
                 33.07 
                 1356.26 
                 956.64 
               
               
                 128 
                 1869.92 
                 31.28 
                 223.93 
                 140.79 
               
               
                 129 
                 1873 
                 21.26 
                 440.7 
                 270.85 
               
               
                 130 
                 1900.07 
                 24.19 
                 920.26 
                 373.01 
               
               
                 131 
                 1914.07 
                 25.67 
                 1519.39 
                 1746.72 
               
               
                 132 
                 1915.72 
                 34.24 
                 180.37 
                 151.24 
               
               
                 133 
                 1917.03 
                 24.99 
                 197.09 
                 216.02 
               
               
                 134 
                 1955.95 
                 27.81 
                 129.24 
                 99.09 
               
               
                 135 
                 2021.11 
                 21.85 
                 346.14 
                 257.95 
               
               
                 136 
                 2041.99 
                 32.56 
                 193.08 
                 127.84 
               
               
                 137 
                 2053.18 
                 20.54 
                 501.38 
                 674.91 
               
               
                 138 
                 2072.15 
                 27.04 
                 601.86 
                 494.89 
               
               
                 139 
                 2077.07 
                 25.44 
                 261.1 
                 214.6 
               
               
                 140 
                 2085.12 
                 33.75 
                 215.62 
                 302.81 
               
               
                 141 
                 2140.12 
                 20.56 
                 256.95 
                 290.52 
               
               
                 142 
                 2166.09 
                 27.84 
                 128.57 
                 52.54 
               
               
                 143 
                 2168.66 
                 34.88 
                 257.1 
                 291.77 
               
               
                 144 
                 2179.03 
                 25.31 
                 84.93 
                 31.65 
               
               
                 145 
                 2278.11 
                 26.17 
                 438.37 
                 314.65 
               
               
                 146 
                 2283.18 
                 26.31 
                 619.59 
                 634.52 
               
               
                 147 
                 2314.3 
                 22.71 
                 1018.08 
                 1167.69 
               
               
                 148 
                 2320.43 
                 23.21 
                 212.67 
                 166.8 
               
               
                 149 
                 2327.24 
                 34.9 
                 1737.42 
                 1517.73 
               
               
                 150 
                 2341.12 
                 26.74 
                 304.17 
                 535.15 
               
               
                 151 
                 2343.24 
                 34.95 
                 270.79 
                 236.16 
               
               
                 152 
                 2368.24 
                 21.24 
                 101.48 
                 105.72 
               
               
                 153 
                 2377.25 
                 28.07 
                 2711.11 
                 1749.4 
               
               
                 154 
                 2390.26 
                 27.33 
                 617.62 
                 500.67 
               
               
                 155 
                 2392.73 
                 35.48 
                 512.31 
                 482.03 
               
               
                 156 
                 2409.28 
                 27.64 
                 275.81 
                 159.58 
               
               
                 157 
                 2410.3 
                 30.62 
                 338.59 
                 232.89 
               
               
                 158 
                 2448.39 
                 21.07 
                 488.24 
                 440.74 
               
               
                 159 
                 2475.21 
                 27.09 
                 757.06 
                 535.45 
               
               
                 160 
                 2475.27 
                 24.74 
                 478.15 
                 297.04 
               
               
                 161 
                 2486.04 
                 35.76 
                 2280.47 
                 1824.17 
               
               
                 162 
                 2500.33 
                 19.99 
                 110.01 
                 94.92 
               
               
                 163 
                 2521.36 
                 19.26 
                 516.08 
                 635.2 
               
               
                 164 
                 2522.35 
                 27.9 
                 4135.44 
                 3306.09 
               
               
                 165 
                 2527.42 
                 19.79 
                 393.22 
                 500.27 
               
               
                 166 
                 2549.29 
                 27.66 
                 99.25 
                 108.48 
               
               
                 167 
                 2584.37 
                 35.6 
                 451.18 
                 260.07 
               
               
                 168 
                 2684.32 
                 21.38 
                 1926.21 
                 155.86 
               
               
                 169 
                 2698.41 
                 22.52 
                 182.49 
                 220.4 
               
               
                 170 
                 2799.17 
                 25.07 
                 445.75 
                 375.83 
               
               
                 171 
                 2816.31 
                 28.74 
                 1366.84 
                 1928.38 
               
               
                 172 
                 2851.42 
                 27.7 
                 495.9 
                 288.67 
               
               
                 173 
                 2923.51 
                 36.73 
                 818.47 
                 883.22 
               
               
                 174 
                 2982.72 
                 19.97 
                 3750.78 
                 5523.72 
               
               
                 175 
                 3019.54 
                 24.72 
                 170.57 
                 189.58 
               
               
                 176 
                 3173.68 
                 22.95 
                 155.36 
                 252.28 
               
               
                 177 
                 3192.67 
                 37.66 
                 689.53 
                 1089.16 
               
               
                 178 
                 3215.61 
                 28.53 
                 1305.23 
                 2016.28 
               
               
                 179 
                 3218.4 
                 30.31 
                 1384.58 
                 1875.79 
               
               
                 180 
                 3221.59 
                 22.7 
                 170.45 
                 217.24 
               
               
                 181 
                 3279.66 
                 25.32 
                 141.5 
                 83 
               
               
                 182 
                 3282.34 
                 36.05 
                 1082.36 
                 1351.09 
               
               
                 183 
                 3298.42 
                 36.17 
                 268.81 
                 282.69 
               
               
                 184 
                 3302.68 
                 23.31 
                 316.81 
                 508.67 
               
               
                 185 
                 3324.7 
                 21.62 
                 422.39 
                 490.7 
               
               
                 186 
                 3386.77 
                 22.21 
                 670.34 
                 395.98 
               
               
                 187 
                 3401.73 
                 23.48 
                 2618.95 
                 4622.56 
               
               
                 188 
                 3408.76 
                 26.04 
                 175.22 
                 94.81 
               
               
                 189 
                 3462.68 
                 21.25 
                 2161.32 
                 2653.08 
               
               
                 190 
                 3466.75 
                 23.9 
                 904.51 
                 559.21 
               
               
                 191 
                 3524.8 
                 31.72 
                 1130.3 
                 410.29 
               
               
                 192 
                 3529.84 
                 23.7 
                 1979.26 
                 2916.13 
               
               
                 193 
                 3595.77 
                 23.89 
                 344.53 
                 455.24 
               
               
                 194 
                 3605.4 
                 21.53 
                 321.29 
                 479.63 
               
               
                 195 
                 3614.82 
                 22.01 
                 161.46 
                 267.85 
               
               
                 196 
                 3644.79 
                 29.39 
                 1038.75 
                 749.16 
               
               
                 197 
                 3645.25 
                 26.69 
                 1161.31 
                 741.33 
               
               
                 198 
                 3650.74 
                 19.9 
                 1029.39 
                 1161.19 
               
               
                 199 
                 3672.71 
                 21.9 
                 1896.48 
                 819.91 
               
               
                 200 
                 3677.74 
                 24.3 
                 1717.39 
                 1567.09 
               
               
                 201 
                 3685.86 
                 22.21 
                 9259.98 
                 16077.47 
               
               
                 202 
                 3687.78 
                 20.58 
                 832.51 
                 1095.77 
               
               
                 203 
                 3693.93 
                 27.15 
                 344.49 
                 218.63 
               
               
                 204 
                 3741.63 
                 20.1 
                 547.74 
                 806.46 
               
               
                 205 
                 3768.77 
                 31.84 
                 533.93 
                 377.59 
               
               
                 206 
                 3782.94 
                 22.68 
                 360.79 
                 364.04 
               
               
                 207 
                 3788.04 
                 25.24 
                 609.58 
                 782.85 
               
               
                 208 
                 3792.76 
                 27.25 
                 682.32 
                 432.09 
               
               
                 209 
                 3819.82 
                 32.74 
                 120.7 
                 133.76 
               
               
                 210 
                 3881.87 
                 24.56 
                 3257.71 
                 1968.09 
               
               
                 211 
                 3903.08 
                 25.71 
                 2177.14 
                 2780.86 
               
               
                 212 
                 3905.8 
                 27.72 
                 23257.92 
                 16304.43 
               
               
                 213 
                 3929.73 
                 23.07 
                 2742.02 
                 3430.19 
               
               
                 214 
                 3934.76 
                 24.02 
                 653.19 
                 487.54 
               
               
                 215 
                 3951.07 
                 22.77 
                 25509.01 
                 32844.44 
               
               
                 216 
                 4005.54 
                 22.57 
                 566.89 
                 387.06 
               
               
                 217 
                 4087.12 
                 26.92 
                 607.44 
                 490.16 
               
               
                 218 
                 4112.78 
                 24.46 
                 267.94 
                 308.15 
               
               
                 219 
                 4131.68 
                 22.54 
                 653.71 
                 586.61 
               
               
                 220 
                 4164.86 
                 25.11 
                 781.59 
                 466.12 
               
               
                 221 
                 4192.99 
                 34.95 
                 1761.93 
                 1496.61 
               
               
                 222 
                 4203.13 
                 26.14 
                 613.9 
                 1051.15 
               
               
                 223 
                 4218.31 
                 20.6 
                 939.4 
                 1360.44 
               
               
                 224 
                 4232.32 
                 32.35 
                 318.48 
                 349.1 
               
               
                 225 
                 4250 
                 27.68 
                 504.35 
                 286.25 
               
               
                 226 
                 4278 
                 25.3 
                 1161.81 
                 745.21 
               
               
                 227 
                 4301.93 
                 21.26 
                 476.37 
                 698.84 
               
               
                 228 
                 4307.09 
                 31.58 
                 157.37 
                 88.2 
               
               
                 229 
                 4349.06 
                 28.17 
                 15449.01 
                 7992.31 
               
               
                 230 
                 4384.07 
                 19.8 
                 465.18 
                 981.39 
               
               
                 231 
                 4428.79 
                 32.86 
                 827.48 
                 433.08 
               
               
                 232 
                 4464.64 
                 21.54 
                 4084.32 
                 2311.8 
               
               
                 233 
                 4468.61 
                 23.47 
                 3429.99 
                 2945.88 
               
               
                 234 
                 4510.97 
                 28.56 
                 1157.68 
                 629.08 
               
               
                 235 
                 4548.03 
                 25.95 
                 3177.96 
                 2703.21 
               
               
                 236 
                 4562 
                 29.31 
                 509.94 
                 403.2 
               
               
                 237 
                 4562 
                 29.31 
                 574.68 
                 403.2 
               
               
                 238 
                 4564.18 
                 26.01 
                 497.67 
                 438.34 
               
               
                 239 
                 4583.84 
                 24.2 
                 7608.37 
                 7241.51 
               
               
                 240 
                 4637.81 
                 27.82 
                 337.27 
                 294.89 
               
               
                 241 
                 4730.71 
                 19.63 
                 797.93 
                 1759.4 
               
               
                 242 
                 4749.41 
                 21.81 
                 725.74 
                 426.89 
               
               
                 243 
                 4750.06 
                 19.53 
                 4365.88 
                 3189.94 
               
               
                 244 
                 4890.59 
                 23.27 
                 1965.12 
                 1418.61 
               
               
                 245 
                 4933.64 
                 20.57 
                 878.93 
                 735.48 
               
               
                 246 
                 4986.98 
                 21.35 
                 637.73 
                 533.05 
               
               
                 247 
                 5039.63 
                 25.68 
                 1039.64 
                 1389.17 
               
               
                 248 
                 5042.1 
                 24.31 
                 3686.99 
                 3120.74 
               
               
                 249 
                 5060.4 
                 20.09 
                 3307.86 
                 1942.65 
               
               
                 250 
                 5110.36 
                 25.28 
                 637.44 
                 697.57 
               
               
                 251 
                 5122.44 
                 20.75 
                 1342 
                 851.23 
               
               
                 252 
                 5157.79 
                 34.26 
                 200.52 
                 208.01 
               
               
                 253 
                 5181.63 
                 25.36 
                 5716.39 
                 4305.72 
               
               
                 254 
                 5258.56 
                 22.09 
                 12476.68 
                 10602.4 
               
               
                 255 
                 5439.46 
                 25.41 
                 713.92 
                 522.3 
               
               
                 256 
                 5495.33 
                 31.72 
                 1776.93 
                 1297.43 
               
               
                 257 
                 5660.6 
                 31.55 
                 893.02 
                 595.49 
               
               
                 258 
                 5745.2 
                 19.72 
                 851.4 
                 1608.76 
               
               
                 259 
                 5891.27 
                 24.16 
                 482.2 
                 422.63 
               
               
                 260 
                 6224.17 
                 25.27 
                 1104.36 
                 995.62 
               
               
                 261 
                 6327.46 
                 22.03 
                 1410.46 
                 1027.79 
               
               
                 262 
                 6498.75 
                 20.1 
                 3989.56 
                 2972.62 
               
               
                 263 
                 6611.97 
                 28.44 
                 311.21 
                 338.55 
               
               
                 264 
                 6617.76 
                 24.03 
                 2799.82 
                 1943.58 
               
               
                 265 
                 6813.98 
                 23.14 
                 4217.01 
                 3699.9 
               
               
                 266 
                 6881.81 
                 21.72 
                 450.1 
                 868.21 
               
               
                 267 
                 6893.8 
                 24.57 
                 2537.57 
                 1569.65 
               
               
                 268 
                 6985.31 
                 21.87 
                 2238.63 
                 1577.04 
               
               
                 269 
                 7026.99 
                 22.02 
                 2132.66 
                 1480.92 
               
               
                 270 
                 7049.04 
                 22.79 
                 8522.63 
                 6229.31 
               
               
                 271 
                 7106.83 
                 23 
                 766.91 
                 575.59 
               
               
                 272 
                 7142.49 
                 21.32 
                 1014.86 
                 557.95 
               
               
                 273 
                 7210.86 
                 22.94 
                 915.21 
                 568.24 
               
               
                 274 
                 8176.16 
                 19.47 
                 11495.92 
                 7835.63 
               
               
                 275 
                 8186.93 
                 20.72 
                 1706.07 
                 1130.11 
               
               
                 276 
                 8289.28 
                 19.39 
                 4317.47 
                 3227.21 
               
               
                 277 
                 9724.01 
                 25.64 
                 3380.24 
                 1957.82 
               
               
                 278 
                 12529 
                 20.64 
                 38234.95 
                 9397.12 
               
               
                 279 
                 14557.83 
                 19.21 
                 1514.79 
                 2225.19 
               
               
                   
               
            
           
         
       
     
     The subject from which the sample in which the presence or absence of one or more polypeptide markers is determined is derived may be any subject which is capable of suffering from Alzheimer&#39;s disease, for example, an animal or human. Preferably, the subject is a mammal, such as a dog or a horse, and most preferably, it is a human. 
     In a preferred embodiment of the disclosure, not just one polypeptide marker, but a combination of markers are used to diagnose Alzheimer&#39;s disease, wherein the existence of Alzheimer&#39;s disease is concluded from their presence or absence. By comparing a plurality of polypeptide markers, a bias in the overall result from a few individual deviations from the typical presence probability in the sick or control individual can be reduced or avoided. 
     The sample in which the presence or absence of the polypeptide marker or markers according to the disclosure is measured may be any sample which is obtained from the body of the subject. The sample is a sample which has a polypeptide composition suitable for providing information about the state of the subject (Alzheimer&#39;s disease or not). For example, it may be blood, urine, synovial fluid, a tissue fluid, a body secretion, sweat, cerebrospinal fluid, lymph, intestinal, gastric or pancreatic juice, bile, lacrimal fluid, a tissue sample, sperm, vaginal fluid or a feces sample. Preferably, it is a liquid sample. 
     In a preferred embodiment, the sample is a urine sample, blood sample, wherein said blood sample may be a (blood) serum or (blood) plasma sample, or a cerebrospinal fluid sample. The cerebrospinal fluid is a liquid that is in contact with the brain and also bathes the spinal cord. From the spinal cord, it can also be withdrawn by puncture with a low expenditure. 
     Blood samples can be taken by methods known in the prior art, for example, from a vein, artery or capillary. Usually, a blood sample is obtained by withdrawing venous blood by means of a syringe, for example, from an arm of the subject. The term “blood sample” includes samples obtained from blood by further purification and separation methods known from the prior art, such as blood plasma or blood serum. 
     The presence or absence of a polypeptide marker in the sample may be determined by any method known in the prior art that is suitable for measuring polypeptide markers. Such methods are known to the skilled person. In principle, the presence or absence of a polypeptide marker can be determined by direct methods, such as mass spectrometry, or indirect methods, for example, by means of ligands. 
     If required or desirable, the sample from the subject, for example, the urine or blood sample, may be pretreated by any suitable means and, for example, purified or separated before the presence or absence of the polypeptide marker or markers is measured. The treatment may comprise, for example, purification, separation, dilution or concentration. The methods may be, for example, centrifugation, filtration, ultrafiltration, dialysis, precipitation or chromatographic methods, such as affinity separation or separation by means of ion-exchange chromatography, or electrophoretic separation. Particular examples thereof are gel electrophoresis, two-dimensional polyacrylamide gel electrophoresis (2D-PAGE), capillary electrophoresis, metal affinity chromatography, immobilized metal affinity chromatography (IMAC), lectin-based affinity chromatography, liquid chromatography, high-performance liquid chromatography (HPLC), normal and reverse-phase HPLC, cation-exchange chromatography and selective binding to surfaces. All these methods are well known to the skilled person, and the skilled person will be able to select the method as a function of the sample employed and the method for determining the presence or absence of the polypeptide marker or markers. 
     In one embodiment of the disclosure, the sample, before being measured, is separated by capillary electrophoresis, purified by ultracentrifugation and/or divided by ultrafiltration into fractions which contain polypeptide markers of a particular molecular size. 
     Preferably, a mass-spectrometric method is used to determine the presence or absence of a polypeptide marker, wherein a purification or separation of the sample may be performed upstream from such method. As compared to the currently employed methods, mass-spectrometric analysis has the advantage that the concentration of many (&gt;100) polypeptides of a sample can be determined by a single analysis. Any type of mass spectrometer may be employed. By means of mass spectrometry, it is possible to measure 10 fmol of a polypeptide marker, i.e., 0.1 ng of a 10 kDa protein, as a matter of routine with a measuring accuracy of about ±0.01% in a complex mixture. In mass spectrometers, an ion-forming unit is coupled with a suitable analytic device. For example, electrospray-ionization (ESI) interfaces are mostly used to measure ions in liquid samples, whereas the matrix-assisted laser desorption/ionization (MALDI) technique is used for measuring ions from a sample crystallized with a matrix. For analyzing the ions formed, quadrupoles, ion traps or time-of-flight (TOF) analyzers may be used. 
     In electrospray ionization (ESI), the molecules present in solution are atomized, inter alia, under the influence of high voltage (e.g., 1-8 kV), which forms charged droplets that become smaller from the evaporation of the solvent. Finally, so-called Coulomb explosions cause the formation of free ions, which can then be analyzed and detected. 
     In the analysis of the ions by means of TOF, a particular acceleration voltage is applied which confers an equal amount of kinetic energy to the ions. Thereafter, the time that the respective ions take to travel a particular drifting distance through the flying tube is measured very accurately. Since with equal amounts of kinetic energy, the velocity of the ions depends on their mass, the latter can thus be determined. TOF analyzers have a very high scanning speed and therefore reach a very high resolution. 
     Preferred methods for the determination of the presence and absence of polypeptide markers include gas-phase ion spectrometry, such as laser desorption/ionization mass spectrometry, MALDI-TOF MS, SELDI-TOF MS (surface-enhanced laser desorption/ionization), LC-MS (liquid chromatography/mass spectrometry), 2D-PAGE/MS and capillary electrophoresis-mass spectrometry (CE-MS). All methods mentioned are known to the skilled person. 
     A particularly preferred method is CE-MS, in which capillary electrophoresis is coupled with mass spectrometry. This method has been described in some detail, for example, in the German Patent Application DE 10021737, in Kaiser et al. (J Chromatogr A, 2003, Vol. 1013: 157-171, and Electrophoresis, 2004, 25: 2044-2055) and in Wittke et al. (Journal of Chromatography A, 2003, 1013: 173-181). The CE-MS technology allows to determine the presence of some hundreds of polypeptide markers of a sample simultaneously within a short time and in a small volume with high sensitivity. After a sample has been measured, a pattern of the measured polypeptide markers is prepared. This pattern can be compared with reference patterns of sick or healthy subjects. In most cases, it is sufficient to use a limited number of polypeptide markers for the diagnosis of Alzheimer&#39;s disease. A CE-MS method which includes CE coupled on-line to an ESI-TOF MS device is further preferred. 
     For CE-MS, the use of volatile solvents is preferred, and it is best to work under essentially salt-free conditions. Examples of suitable solvents include acetonitrile, methanol and the like. The solvents can be diluted with water or admixed with a weak acid (e.g., 0.1% formic acid) in order to protonate the analyte, preferably the polypeptides. 
     By means of capillary electrophoresis, it is possible to separate molecules by their charge and size. Neutral particles will migrate at the speed of the electro-osmotic flow upon application of a current, while cations are accelerated towards the cathode, and anions are delayed. The advantage of capillaries in electrophoresis resides in their favorable ratio of surface to volume, which enables a good dissipation of the Joule heat generated during the current flow. This in turn allows high voltages (usually up to 30 kV) to be applied and thus a high separating performance and short times of analysis. 
     In capillary electrophoresis, silica glass capillaries having inner diameters of from 50 to 75 μm are usually employed. The lengths employed are from 30 to 100 cm. In addition, the capillaries are usually made of plastic-coated silica glass. The capillaries may be both untreated, i.e., expose their hydrophilic groups on the interior surface, or coated on the interior surface. A hydrophobic coating may be used to improve the resolution. In addition to the voltage, a pressure may also be applied, which typically is within a range of from 0 to 1 psi. The pressure may also be applied only during the performance or altered meanwhile. 
     In a preferred method for measuring polypeptide markers, the markers of the sample are separated by means of capillary electrophoresis, then directly ionized and transferred on-line to a mass spectrometer coupled thereto for detection. 
     In the method according to the disclosure, it is advantageous to use several polypeptide markers for the diagnosis of Alzheimer&#39;s disease. In particular, at least three polypeptide markers may be used, for example, markers 1, 2 and 3; 1, 2 and 4; etc. 
     More preferred is the use of at least 4, 5 or 6 markers. Even more preferred is the use of at least 13 markers, for example, markers 1 to 13. Most preferred is the use of all 279 markers listed in Tables 1 to 3. 
     In one embodiment, markers 123, 144, 167, 38, 255, 257 and 72 are employed. 
     In order to determine the probability of the existence of Alzheimer&#39;s disease when several markers are used, statistic methods known to the skilled person may be used. For example, the Random Forests method described by Weissinger et al. (Kidney Int., 2004, 65: 2426-2434) may be used by using a computer program such as SPlus. 
     Example 
     1. Sample Preparation 
     For detecting the polypeptide markers for Alzheimer&#39;s disease, cerebrospinal fluid was employed. Cerebrospinal fluid was withdrawn by a lumbar puncture from healthy donors (control group) as well as from patients suffering from Alzheimer&#39;s disease. Control samples from 6 persons (age 32-64 years) without neurological or psychiatric diseases were used. The cerebrospinal fluid samples for the Alzheimer group were derived from 23 patients (age 57-76 years), those for the MCI group were derived from 8 patients (age 60-75 years). 
     For the subsequent CE-MS measurement, the large proteins occurring in cerebrospinal fluid, such as albumin and immunoglobulins, had to be separated off by ultrafiltration. Thus, 700 μl of cerebrospinal fluid was removed and admixed with 700 μl of filtration buffer (4 M urea, 10 mM NH 4 OH, 0.02% SDS). This 1.4 ml of sample volume was ultrafiltrated (Amicon 30 kDa, Millipore, Bedford, USA). The ultrafiltration was performed at 3000 rpm in a centrifuge until 1.2 ml of ultrafiltrate was obtained. 
     The 1.2 ml of filtrate obtained was then applied to a Pharmacia C-2 column (Pharmacia, Uppsala, Sweden) in order to remove urea, salts and other disturbing components. The bound polypeptides were then eluted from the C-2 column with 50% acetonitrile, 0.5% formic acid in water, and lyophilized. For the CE-MS measurement, the polypeptides were resuspended with 20 μl of water (HPLC grade, Merck). 
     2. CE-MS Measurement 
     The CE-MS measurements were performed with a capillary electrophoresis system from Beckman Coulter (P/ACE MDQ System; Beckman Coulter Inc., Fullerton, USA) and an ESI-TOF mass spectrometer from Bruker (micro-TOF MS, Bruker Daltonik, Bremen, Germany). 
     The CE capillaries were supplied by Beckman Coulter and had an ID/OD of 50/360 μm and a length of 90 cm. The mobile phase for the CE separation consisted of 30% methanol and 0.5% formic acid in water. For the “sheath flow” on the MS, 30% isopropanol with 0.5% formic acid was used at a flow rate of 2 μl/min. The coupling of CE and MS was realized by a CE-ESI-MS Sprayer Kit (Agilent Technologies, Waldbronn, Germany). 
     For injecting the sample, a pressure of from 1 to a maximum of 6 psi was applied, and the duration of the injection was 99 seconds. With a pressure of 1 psi, about 150 nl of the sample was injected into the capillary, which corresponds to about 10% of the capillary volume. A stacking technique was used to concentrate the sample in the capillary. Thus, before the sample was injected, a 1 M NH 3  solution was injected for 7 seconds (at 1 psi), and after the sample was injected, a 2 M formic acid solution was injected for 5 seconds. After the separation voltage (30 kV) was applied, the analytes were automatically concentrated between these solutions. 
     The subsequent CE separation was performed with a pressure method: 40 minutes at 0 psi, then 0.1 psi for 2 min, 0.2 psi for 2 min, 0.3 psi for 2 min, 0.4 psi for 2 min, and finally 0.5 psi for 32 min. The total duration of a separation run was thus 80 minutes. 
     In order to obtain as good as possible a signal intensity on the side of the MS, the nebulizer gas was set to the lowest possible value. The voltage applied for generating the electrospray was 3700-4100 V. The remaining settings at the mass spectrometer were optimized for peptide detection according to the manufacturer&#39;s protocol. The spectra were recorded over a mass range of m/z 350 to m/z 3000 and accumulated every 3 seconds. 
     3. Standards for the CE Measurement 
     For checking and calibrating the CE measurement, the following proteins or polypeptides which are characterized by the stated CE migration times under the selected conditions were employed: 
     
       
         
           
               
               
             
               
                   
               
               
                 Protein/polypeptide 
                 Migration time 
               
               
                   
               
             
            
               
                 Aprotinin (SIGMA, Taufkirchen, DE, Cat. # A1153) 
                  9.2 min 
               
               
                 Ribonuclease (SIGMA, Taufkirchen, DE, Cat. # R4875) 
                 10.9 min 
               
               
                 Lysozyme (SIGMA, Taufkirchen, DE, Cat. # L7651) 
                  8.9 min 
               
               
                 “REV”, Sequence: REVQSKIGYGRQIIS 
                 15.6 min 
               
               
                 “ELM”, Sequence: ELMTGELPYSHINNRDQIIFMVGR 
                 23.4 min 
               
               
                 “KINCON”, Sequence: TGSLPYSHIGSRDQIIFMVGR 
                 20.0 min 
               
               
                 “GIVLY” Sequence: GIVLYELMTGELPYSHIN 
                 36.8 min 
               
               
                   
               
            
           
         
       
     
     The proteins/polypeptides were employed at a concentration of 10 μmol/μl each in water. “REV”, ELM, “KINCON” and “GIVLY” are synthetic peptides. 
     The molecular masses of the peptides and the m/z ratios of the individual charge states visible in MS are as follows: 
                                        H (mono)                                                 1.0079   1.0079   1.0079   1.0079   1.0079   1.0079   1.0079           Aprotinin   Ribonuclease   Lysozyme   REV   KINCON   ELM   GIVLY       m/z   Mono Mass   Mono Mass   Mono Mass   Mono Mass   Mono Mass   Mono Mass   Mono Mass                                                     0   6513.09   13681.32   14303.88   1732.96   2333.19   2832.41   2048.03       1   6514.0979   13682.328   14304.888   1733.9679   2334.1979   2833.4179   2049.0379       2   3257.5529   6841.6679   7152.9479   867.4879   1167.6029   1417.2129   1025.0229       3   2172.0379   4561.4479   4768.9679   578.6612   778.7379   945.1446   683.6846       4   1629.2804   3421.3379   3576.9779   434.2479   584.3054   709.1104   513.0154       5   1303.6259   2737.2719   2861.7839   347.5999   467.6459   567.4899   410.6139       6   1086.5229   2281.2279   2384.9879   289.8346   389.8729   473.0762   342.3462       7   931.4494   1955.4822   2044.4193   248.5736   334.3208   405.6379   293.5836       8   815.1442   1711.1729   1788.9929   217.6279   292.6567   355.0592   257.0117       9   724.6846   1521.1546   1590.3279   193.559   260.2512   315.7201   228.5668       10   652.3169   1369.1399   1431.3959   174.3039   234.3269   284.2489   205.8109       11   593.107   1244.7643   1301.3606   158.5497   213.1161   258.4997   187.1924       12   543.7654   1141.1179   1192.9979   145.4212   195.4404   237.0421   171.6771       13   502.0148   1053.4171   1101.3063   134.3125   180.4841   218.8856   158.5486                    
4. Comparison of the Markers According to the Disclosure with the Prior Art
 
     In Electrophoresis 26 (2005), 1476-1487, Wittke et al. describe ten markers in Table 1 that are supposed to be indicative of Alzheimer&#39;s disease. Further studies have shown that the markers found only have a lower specificity. 
       FIG. 1   a  shows the significance of the biomarkers from this publication. Shown are the biomarkers with the IDs 108317 (ID paper 356), 108983 (ID paper 362), ID 128206 (ID paper 472), ID 131316 (ID paper 490), ID 131401 (ID paper 491) and ID 136537 (ID paper 515). 
       FIG. 1   b  shows the significance of further biomarkers from this publication. Shown are the biomarkers with the IDs 49693 (ID paper 51), 66564 (ID paper 111), ID 75674 (ID paper 142), ID 89174 (ID paper 208). 
     It is clearly seen that the predictive value is almost 0 for almost each of the ten markers included in the publication, in contrast to the markers claimed according to the disclosure. 
       FIGS. 2   a  and  b  show the corresponding analysis for twelve markers according to the disclosure. These result in a concrete separation between the groups (healthy vs. Alzheimer&#39;s). By selecting at least three markers, the analysis reaches an accuracy of 84%.