Ceruloplasmin and SOD1 in heterozygotes for Wilson disease disease Table 1 GGT activity, copper concentration, CP concentration, CP oxidative activity, CP speciﬁc oxidative activity and SOD1activity in 20 heterozygotes for Wilson disease with their age- and gender-matched controls.The number of pairs is indicated and the P values of the comparisons of the means.The hypothesis was rejected for values than 0.05.The results of same determinations are also shown in the 5 homozygotes known in Iceland at the time of the study Determinations Heterozygotes Controls P-values Homozygotes Mean (range) Mean (range) Mean (range) GGT units/l (serum) Copper conc. μmol/l (plasma) CP conc. μmol/l (serum) CP oxidative activity units/ml (serum) CP speciﬁc oxidative activity units/μmol *10−4 (serum) SOD1 activity, SOD 525 units (erythrocytes) 25 (12–86) 18 (11–32) 2.3 (1.3–3.6) 137 (82–211) 6.2 (3.7–11.1) 360 (265–476) 28 (16–68) 19 (12–33) 2.3 (1.4–4.1) 152 (65–227) 6.9 (2.8–9.4) 328 (250–437) 0.104*² 0.507**¹ 0.539¹ 0.170¹ 0.392¹ 0.066*² 61 (14–194) 3.2 (2–5) α 29 (17–36) β 352 (319–376) Abbreviations: GGT, gamma glutamyl transpeptidase; CP, ceruloplasmin; SOD1, Cu-Zn superoxide dismutase. Notes: ¹Student’s two sample t test, in a normally distributed sample; ² Wilcoxon’s two sample test, were the sample is not normally distributed; *Not normally distributed after logarithmic transformation; **Normally distributed after logarithmic transformation; α Under the det.lim. of the laboratory; β Not calculated as the CP concentration is not available. 5,6,6a,11b-tetrahydro-3,9,10-trihydroxybenzofluorene (BXT-01050) in aqueous alkaline solution. The kinetic mea- surement of 525-nm absorbance is performed for 1 minute upon the addition of BXT-01050. The SOD activity was determined from the ratio of the auto-oxidation measured in the presence and in the absence of the sample. One SOD activity unit (U-525) has been deﬁned as the activity that doubles the auto-oxidation background. The reagents used in the analyses were obtained from Oxis International, Inc., Portland, OR, USA. Ceruloplasmin speciﬁc oxidative activity The speciﬁc oxidative activity of CP in serum (oxidative activity relative to mass) was calculated as CP oxidative activity, units/ml, divided by the value of CP concentration. This is represented as units/μmol*10−4 in Table 1. Statistics Ceruloplasmin concentration, oxidative activity and speciﬁc oxidative activity were normally distributed in the controls. The GGT activity and copper concentration did not pass normality tests (D’Augostino and Pearson omnibus and Shapiro–Wilk), but did so after the transformation to loga- rithmic ﬁgures. The SOD1 activity did not pass the normality tests, and transformation of the SOD1 values to logarithmic ﬁgures did not change this. For this reason, SOD1 activity in heterozygotes and the age- and gender-matched controls were compared by using Wilcoxon’s two-sample test. The student’s two-way t-test was used for comparing the results of the logarithmic ﬁgures of GGT and copper and for the determinations of CP concentration, oxidative activity and Neuropsychiatric Disease and Treatment 2009:5 speciﬁc oxidative activity in the heterozygotes and their age- and gender-matched controls. The calculations were done by GraphPad Prism®, but Figure 1 was made by Med Calc®. The hypothesis was rejected for P values 0.05. Results The results of the determinations on the WD patients, heterozy- gotes, and their controls are represented in Table 1 and Figure 1. Discussion There was no signiﬁcant difference in the activity of GGT in the heterozygotes compared with the controls. One WD patient had raised GGT. This patient was diagnosed with liver cancer shortly after the time of the study, probably as a late complication of WD. All the Icelandic WD patients had lowered copper in plasma and lowered CP concentration and CP activity in serum. The SOD1 activity in erythrocytes was normal in the WD patients, although the SOD1 activity in all but one patient was above the median value of the control group for the heterozygotes (Figure 1). This could reﬂect mild intracellular copper retention in spite of the lowered copper in plasma, lowered CP determinations in serum and the copper-chelating treatment in the WD patients. In this study the CP concentration, CP oxidative activity and CP speciﬁc oxidative activity (activity related to mass, reﬂecting the quality of the protein) in serum were not signiﬁcantly different in the heterozygotes compared with the control group. This is in line with earlier studies.4,5,12 Furthermore, the copper in plasma was not signiﬁcantly 57