Association between monoamine oxidase (MAO)-A gene variants and schizophrenia in a Chinese population.

Monoamine oxidase (MAO) A is a critical enzyme in the catabolism of dopamine. Dysfunction of dopaminergic systems has been implicated in the pathophysiology of schizophrenia, suggesting that MAOA gene variation might be associated with the disorder. MAOA gene variation was compared between 234 Chinese schizophrenic patients and 121 healthy controls. Three polymorphic markers of the MAOA gene were analyzed using PCR techniques: two MAOA restriction fragment length polymorphisms (RFLP), -941G/T and -1460C/T, and the variable number tandem repeats (VNTR) in the promoter region. Linkage disequilibrium and haplotype analyses were performed with Bonferroni correction for multiple testing. In single marker analyses the 941T allele was significantly associated with schizophrenia in men (p=0.01). Haplotype analyses revealed a significant overall difference (p=0.03) between schizophrenia and control men, with higher frequencies of haplotypes containing the major allele (T) of -941T/G and the short allele (3 repeats) of the VNTR polymorphisms. No significant associations were detected for females using single markers or haplotypes. These findings suggest that genetic variants in MAOA may play a role in susceptibility to schizophrenia in Chinese men.