The gamma amino butyric acid (GABA) receptor alpha-3 subunit gene polymorphism in unipolar depressive disorder: a genetic association study.

There is evidence that genes coding for the gamma aminobutyric acid (GABA) receptor may be involved in the etiology of affective disorders. Recently, an association between a CA-repeat in the GABRA 3 gene and bipolar disorder had been reported. The present study aimed at investigating the association between this polymorphism and unipolar major depressive disorder. The sample consisted of 201 unipolar depressive patients and 151 healthy subjects. All study participants were unrelated German individuals of the same ethnogeographical origin. No differences in genotype frequencies between unipolar patients and healthy subjects were found for GABRA 3 (P = 0.08). However, a significant difference of allelic frequencies was observed in female patients (n = 128) compared to female controls (n = 81) (P < or = 0.0001). This effect was not present in the group of male patients (n = 73) compared to male healthy subjects (n = 70) (P = 0.24). The results of our study indicate that GABRA 3 gene might also be involved in the genetic pathophysiology of unipolar major depressive disorder (at least in female patients), even if the findings do not support a predominant role of GABRA 3.