Family-based association studies of alpha-adrenergic receptor genes in chromosomal regions with linkage to bipolar affective disorder.

Several lines of evidence suggest an involvement of the noradrenergic neurotransmitter system in the pathogenesis of bipolar affective disorder (BPAD). Three genes for alpha-adrenergic receptors (ADRA) are located in chromosomal regions that showed evidence for linkage: The alpha(1c)-adrenergic (ADRA-1C) receptor gene on 8p21, the alpha(2a)-adrenergic (ADRA-2A) receptor gene on 10q25, and the alpha(2c)-adrenergic (ADRA-2C) receptor on 4p16. In a BPAD sample of 120 parent-offspring triads, we genotyped a 492 Cys/Arg variant in exon 2 of the ADRA-1C gene, a -1291 G/C variant in the 5'UTR of the ADRA-2A gene, and a STR marker (adra2c1) in the 5'UTR of the ADRA-2C gene. Using the Transmission Disequilibrium Test (TDT), no significant differences in transmissions were observed for any of the three ADRA genes.