Genetic Factors Genetic Factors for Late-Onset Alzheimer's. Studies have reported greatest deposits of beta amyloid in people with ApoE4, fewer in ApoE3, and lowest in those with ApoE2. Some research indicates that ApoE3 and ApoE4 may induce changes in beta amyloid that trigger an inflammatory response in the brain. ApoE2 appears, on the other hand, to have protective qualities. Alzheimer's disease is not inevitable, however, even in people with two copies of the ApoE4 gene.
Reports vary widely in estimating the extent of risk.
Some research indicates that a specific variation of the ApoE4 gene may be the primary culprit in the development of Alzheimer's, which would explain why many people with ApoE4 exhibit no signs of Alzheimer's. ApoE4 has been studied for years as a risk factor for coronary artery disease, and some studies have found a higher risk for atherosclerosis in people with Alzheimer's disease who also carry two copies of the ApoE4 genotype. Most people with Alzheimer's disease, however, do not carry the ApoE4 gene. Increasingly, researchers believe that many cases of late-onset Alzheimer's disease are a result of a collaboration of genetic factors that participate in the process of producing or degrading beta amyloid. Such mutations are not inherited, but appear to be genetic mistakes that occur during transcription'the coding process in which DNA establishes the pattern for the production of proteins and other molecules.