Genetic susceptibility to tardive dyskinesia in chronic schizophrenia subjects: III. Lack of association of CYP3A4 and CYP2D6 gene polymorphisms

Tardive dyskinesia is a severe debilitating movement disorder characterized by choreoathetotic movements developing in one-fifth of the patients with schizophrenia. In this study we have investigated the significance of CYP3A4*1B and CYP2D6*4 polymorphisms in TD susceptibility among chronic schizophrenia patients (n=335) from north India. Tardive dyskinesia was diagnosed in ∼29% (96/335) of these patients. No significant association of either of the two SNPs with TD (CYP3A4*1B χ2=0. 308, df=1, p=0.579; CYP2D6*4 χ2=0.006, df=1, p=0.935) was observed. However a trend towards increased severity of TD in patients heterozygous for the CYP2D6*4 mutation was observed.