Seasonal affective disorder and the G-protein β-3-subunit C825T polymorphism

Guanine nucleotide-binding proteins (G-proteins) have been implicated in affective disorders, with reports of altered signal transduction and G-protein levels. Association with seasonal affective disorder (SAD) has been found for the higher activity T-allele of the G-protein β-3-subunit C825T polymorphism. European SAD patients ( n = 159) and matched controls ( n = 159) were genotyped for the C825T. Seasonality and diurnal preference were investigated in subsets of the material ( n = 177 and 92, respectively). We found no association between C825T and SAD (χ 2 = .09, p = .96) or seasonality ( F = 1.76, p = .18). There was some evidence for an effect on diurnal preference but only in the control group ( n = 46, t = −2.8, Bonferroni corrected p = .045). These results suggest that the G-protein β-3-subunit 825 T-allele does not play a major role in susceptibility to seasonal affective disorder in the population studied.