The gamma-aminobutyric acid (GABA) neurotransmitter system has been im
plicated in the pathogenesis of mood disorders, To test this hypothesi
s we carried out an association study between a dinucleotide repeat po
lymorphism in the GABA(A) receptor alpha 5 subunit gene and bipolar an
d unipolar mood disorders. Our results suggest a possible involvement
of this gene in unipolar but not in bipolar disorder.