Genetic polymorphism of glutathione S-transferase T1: A candidate genetic modifier of individual susceptibility to schizophrenia

Schizophrenia is highly heritable, but the specific genes involved remain to be determined. A genome wide scan approach has indicated that human chromosome 22q11.2 potentially influences schizophrenia susceptibility. The gene encoding glutathione S-transferase T1 (GSTT1), which pertains to phase II biotransformation enzymes, was also mapped to the above-mentioned band. The present case–control study was performed on 292 (206 males, 86 females) in-patients with schizophrenia, and a total of 292 healthy blood donors matched to the patients according to age (± 5 years) and gender as a control group. The patients were chronic cases. The patients were diagnosed as chronic schizophrenia according to structured clinical interview using the Structured Clinical Interview for DSM-IV (clinician version) to confirm and document DSM-IV diagnosis. The GSTT1 genotypes were determined using a PCR-based method. The GSTT1 null genotype was 17.8% and 33.9% in the patients and control groups, respectively. The GSTT1 null genotype was associated with a significantly reduced risk of developing schizophrenia. On the other word, the positive GSTT1 genotype significantly increased the risk of schizophrenia. The present finding indicated that GSTT1 is a candidate gene for susceptibility to schizophrenia.