Background: Monoamine oxidase (MAO) is a critical enzyme in deamination of biogenic amines and may be involved in the pathophysiology of major psychosis, including mood disorder and schizophrenia. Recently, evidence for genetic association between the MAO-A gene and bipolar mood disorder was obtained in Caucasians.
Methods: We investigated the polymorphisms of the MAO-A gene, which may be related to enzyme activity (T/941/G, A/1609/G), with amino-acid change (A/1609/G), in Japanese patients with bipolar disorder patients (n = 132), unipolar major depression (n = 43), or schizophrenia (n = 95), and controls (n = 169).
Results: No difference in the allele frequencies or genotype distribution of the T/941/G variation was observed between any disease group and the control group. As for the A/1609/G variation, no G allele was found in the Japanese subjects.
Conclusions: No evidence for the genetic association between the MAO-A gene and major psychosis was obtained in the Japanese subjects.