Background: There is compelling evidence for the existence of susceptibility genes for bipolar disorder. Association studies using functional DNA variations are an important approach for identifying these genes. The enzyme catechol-O-methyltransferase (COMT) plays a key role in the degradation of catecholamine neurotransmitters and is a candidate for involvement in bipolar disorder. Recently a common functional genetic polymorphism that underlies population variation in COMT activity has been elucidated and a simple assay developed.
Method: In a collaboration involving seven European centres, we have undertaken an association study of this functional polymorphism in 412 unrelated West European caucasian DSM-III-R bipolar patients and 368 ethnically matched controls.
Results: We found no evidence of allelic or genotypic association.
Conclusions: We can conclude that variation at this functional polymorphism does not make an important contribution to bipolar disorder in the Western European population. Future studies using this powerful experimental approach can be expected to contribute to identification of bipolar susceptibility genes.