Association analysis between dopamine receptor genes and bipolar affectivedisorder

We have performed a case-control analysis of dopamine D2-like receptor (DRD 2 DRD3 and DRD4) gene polymorphisms in 118 Han Chinese cases with bipolar a ffective disorder and 196 control subjects, and replication analysis in 157 English cases and 143 control subjects. We, found association between a fu nctional DRD2 promoter variant (P = 0.03 by allele) and the DRD2 taq1A poly morphism (P = 0.001 by allele) in Chinese bipolar disorder patients. Howeve r, this finding was not replicated in the Caucasian subjects, indicating th at the significant association we observed in the Chinese population is a f alse positive finding. An alternative explanation is that these polymorphis ms are risk factors in Chinese but not Caucasian populations, a hypothesis which seems unlikely in view of the similarity of the clinical characterist ics of bipolar disorder in the two populations. We also report a novel, rar e one-repeat variant of the DRD4 exon 3 VNTR repeat in Chinese populations, which appears to be absent in Caucasians and is not associated with diseas e. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.