Distribution of androgen receptor CAG repeat polymorphism in Chinese schizophrenia and its correlation with age at...

The action of androgens is mediated by the androgen receptors (ARs), which are located throughout the brain. The AR gene is implicated in the pathogenesis of schizophrenia because male siblings with schizophrenia share alleles at this gene at a rate higher than chance predicts, and differences in sex hormone function may explain the gender difference in schizophrenic manifestations. Since the shorter alleles of the AR CAG repeat polymorphism are associated with increased gene expression, we tested the hypothesis that the AR CAG repeat variant confers susceptibility to schizophrenia using a sample of 225 people with schizophrenia and 247 normal controls. Using the median AR repeat length in the normal group as the arbitrary cut-off point (<24 and >25 CAG repeats), the results show no association between the AR repeat length and schizophrenia in either sex. Furthermore. AR CAG repeat length did not affect the age of symptom onset in the schizophrenic population. Our findings suggest that it is unlikely that the AR CAG repeat polymorphism plays a major role in the pathogenesis of schizophrenia. Nevertheless, given that androgens affect cognitive function, violent behavior and mood, the effect of the AR CAG polymorphism on the clinical manifestations of schizophrenia may warrant further exploration.