Association betweenCYP1A2gene single nucleotide polymorphisms and clinical responses to clozapine in patients with treatment-resistant schizophrenia
ObjectivesDespite clozapine's superior clinical efficacy in treatment-resistant schizophrenia (TRS), its adverse effects, need for periodic leukocyte monitoring, cost and variable clinical outcomes mandate a clinical need to predict its treatment response. Although cytochrome P450 1A2 (CYP1A2) is the principal determinant of metabolism of clozapine, the role ofCYP1A2gene in the clinical response to clozapine is uncertain. Hence, we investigated its association with treatment responses and adverse events of clozapine in TRS.MethodsWe evaluated four single nucleotide polymorphisms (SNP) in theCYP1A2gene, clinical responses and serum clozapine levels in 101 consecutive patients with TRS on stable doses of clozapine. We defined clozapine responsea prioriand investigated allelic and genotypic associations. We assessed the socio-demographic and clinical profiles, premorbid adjustment, traumatic life events, cognition and disability of the participants, using standard assessment schedules for appropriate multivariate analyses.ResultsOur results revealed thatCYP1A2gene SNP (*1C, *1D, *1Eand*1F) were not associated with clozapine treatment response, adverse effects, serum clozapine levels or with disability (pvalues > 0.10).ConclusionAsCYP1A2gene SNP do not help to predict the clinical response to clozapine, routine screening for them prior to start clozapine is currently unwarranted. We suggest future longitudinal genome-wide association studies investigating clinical and pharmacogenetic variables together.