Neither single-marker nor haplotype analyses support an association between monoamine oxidase A gene and bipolar disorder.

Monoamine oxidase A (MAOA) abnormality has been suggested as a crucial factor in the pathogenesis of mood disorder, because MAOA is associated with the metabolism of monoamines such as serotonin and norepinephrine. Various MAOA gene polymorphisms have been investigated for possible associations with bipolar disorder (BD), but the results are controversial. Our goal was to investigate whether MAOA gene polymorphisms, especially the promoter uVNTR polymorphism and the EcoRV polymorphism, are associated either with BD or with different clinical subtypes of BD. A total of 714 Han Chinese subjects in Taiwan (305 controls and 409 BD patients) were recruited for study. All subjects were interviewed with the Chinese Version of the Modified Schedule of Affective Disorders and Schizophrenia-Lifetime; BD was diagnosed according to DSM-IV criteria. Genotyping for MAOA polymorphisms was performed using PCR and restriction fragment length polymorphism. The MAOA promoter polymorphisms uVNTR and EcoRV were not associated with BD or any of its subtypes, in either the frequencies of alleles or genotypes. In multiple logistic regression and haplotype frequency analysis, we confirmed these negative results in both females and males. Our results suggest that MAOA polymorphisms do not play a major role in pathogenesis of BD or its clinical subtypes in Han Chinese.