Objective: Recent studies have revealed positive associations between tardive dyskinesia (TD) and genetic polymorphisms of several cytochrome P450 (CYP) subfamilies that are involved in pharmacokinetic process of antipsychotic drugs. In the present study, we analyzed the relationship between TD and two polymorphisms of the CYP1A2 gene, 734C/A and −2964G/A, in a sample of Japanese patients with schizophrenia.
Methods: We studied 199 Japanese patients with schizophrenia. We used the Abnormal Involuntary Movement Scale to evaluate TD. Two polymorphisms of the CYP1A2 gene, 734C/A and −2964 G/A were genotyped by means of polymerase chain reaction and restriction fragment length polymorphism analysis.
Results: Neither the 734C/A nor the −2964G/A polymorphism was associated with TD [734C/A genotype: χ2=0.02, degrees of freedom (df)=2, P=1.00; allele: χ2=0.02, df=1, P=0.89; −2964G/A genotype: χ2=0.21, df=2, P=0.90; allele: χ2=0.15, df=1, P=0.70]. In addition, CYP1A2 haplotype was associated with TD (χ2=0.24, df=3, P=0.97). Furthermore, in both the subgroup of smokers and the subgroup of patients receiving high-dosage antipsychotics (chlorpromazine equivalent >1000 mg), neither the 734C/A nor the −2964G/A polymorphism was associated with TD.
Conclusions: We did not find significant associations between the 734C/A and −2964G/A polymorphisms of CYP1A2 gene and TD in Japanese patients with schizophrenia. Our results suggest that these CYP1A2 gene polymorphisms may not contribute to TD susceptibility.