CYP2D6*17 polymorphism and tardive dyskinesia in black psychotic patients on typical antipsychotics

Josiah T Masuka, Star Khoza, Dixon Chibanda, Walter Mangezi, Charles FB Nhachi


Background: Tardive dyskinesia is a debilitating, intractable, hyperkinetic movement disorder which contributes to an increase in psychiatric morbidity. Reduced function CYP2D6 alleles have been associated with tardive dyskinesia pathogenesis amongst Caucasians and Asians, with CYP2D*4 and *6 and CYP2D6*10 being implicated in these races respectively. No similar study has been successfully conducted in black Africans.

Objective: To determine the relationship between tardive dyskinesia and CYP2D6*17 (the major reduced function CYP2D6 allele in Africans).

Methodology: Abnormal Involuntary Movements Scale (AIMS) scoring and CYP2D6 genotyping were carried out on psychiatric patients exposed to typical antipsychotic medications in an unmatched case control study. A case of tardive dyskinesia was defined as a patient with an AIMS score ≥ 2 in two body areas OR ≥ 3 in one body area

Results: A total of 18 cases and 32 controls made up the study sample.The sample’s mean age was 36.9±12.0 years with median treatment duration of 7.0 years (range: 0.25 to 38 years). Multiple logistic regression revealed no significant association between tardive dyskinesia and CYP2D6*17 (OR=0.252; 95% CI: 0.038 to 1.647; p=0.150). However, use of chlorpromazine (OR=5.754; 95% CI: 1.024 to 32.328; p=0.047) and age at treatment initiation (OR=1.146; 95% CI: 1.021 to 1.287; p=0.021) were independent predictors of tardive dyskinesia.

Discussion: These findings suggest that there is no association between CYP2D6*17and tardive dyskinesia in African psychotic patients on typical antipsychotics. However, more studies with larger sample sizes are required to provide more definitive conclusions regarding the nature of the relationship betweenCYP2D6*17 and tardive dyskinesia.

Key words: Tardive dyskinesia, CYP2D*17, typical antipsychotics

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