Association between bipolar disorder and monoamine oxidase A gene polymorphisms: Results of a multicenter study

Objective: Although genetic factors have been implicated in the etiology of bipolar disorder, no specific gene has been conclusively identified, Given the link between abnormalities in serotonergic neurotransmission and bipol ar disorder, a candidate gene association approach was applied Lo study the involvement of the monoamine oxidase A (MAOA) gene, which codes for a cata bolic enzyme of serotonin, in the susceptibility to bipolar disorder. Method: In France and Switzerland, 272 patients with bipolar disorder and 1 22 healthy subjects were typed for three polymorphic markers of the MAOA ge ne: the MAOA-CA repeat, the MAOA restriction fragment length polymorphism ( RFLP), and a repeat directly adjacent to the variable number of tandem repe ats (VNTR) locus. Results: A significant difference in the distribution of the alleles for the MAOA-CA repeat was observed between the female bipolar patients and comparison group. Conclusions: The results obtained in the French and Swiss population confir m findings from two studies conducted in the United Kingdom.