Association Between Monoamine Oxidase A Gene (CA)n Polymorphism and Risk for Schizophrenia in the Chinese Population

Abstract

Monoamine oxidase plays an important role in the central regulation of monoamine neurotransmitters which are implicated in the pathogenesis of schizophrenia, mood regulation and abnormal behaviours such as impulsivity, suicide and violence. We conducted a population based case-control study to investigate the association of the microsatellite CA-repeats in intron 2 of the MAOA gene, located on the X chromosome, with the susceptibility for schizophrenia and its associated neurocognitive and behavioural phenotypes in the Han Chinese population. Four-hundred-eighty-six unrelated schizophrenic patients with detailed clinical and neurocognitive assessment and 516 healthy subjects were recruited in Hong Kong. We found a significant association between MAOA allele 116 and male patients with schizophrenia (chisquare = 9.68, P = 0.002, odds ratio = 1.64, 95% confidence interval = 1.20–2.24). Further analysis of the clinical and neurocognitive variables in male patients showed a significant association between MAOA allele 116 and history of suicidal behaviour (chi-square = 11.49, P = 0.001, odds ratio = 2.27, 95% confidence interval = 1.41–3.65). Our findings suggest that either the MAOA microsatellite CA-repeats itself or a nearby genetic variant in linkage disequilibrium may influence the risk for schizophrenia and suicidal tendency in men. This may also imply a different genetic mechanism for male and female for expression of the schizophrenia phenotype. Further studies to examine the functional implication of the MAOA microsatellite CA-repeats and its nearby genetic variants in the gender specific pathogenesis of schizophrenia are necessary.