GABRB3 gene locus in affective disorders: An association study

There is accumulated evidence that the genes coding for the receptor of gamma-aminobutyric acid (GABA), the most important inhibitory neurotransmitter in the CNS, may be involved in the pathogenesis of affective disorders. In a previous study, we have found a genetic association between the GABA-A receptor alpha 5 subunit gene locus (GABRA5) on chromosome 15q11-13 and bipolar affective disorder. The aim of the present study was to examine if GABA receptor beta 3 subunit gene, which is located in the same chromosomal region, is also associated with affective illness. The sample consisted of 41 unipolar and 53 bipolar patients compared to 50 controls (blood donors). All subjects were Greek, unrelated among them and were personally interviewed. Diagnosis was based on DSM-IV and ICD-10 criteria. The marker used was a dinucleotide (CA) repeat polymorphism with 13 alleles 177 to 201 basepairs long. The statistical analysis did not show differences in allelic distribution between patients (unipolar as well as bipolar) and controls. According to these results, the gene coding for the beta 3 subunit of the GABA-A receptor does not seem to be implicated in the pathogenesis of affective illness.