Objectives: Antipsychotics-induced tardive dyskinesia (TD) has been suggested to be related to altered dopaminergic neurotransmission in the striatum. Melatonin has a modulating effect on dopaminergic neurotransmission in the brain; therefore, the hypothesis of an association between the melatonin receptor genes (MTNR1A, MTNR1B) and antipsychotics-induced TD was examined in this study.
Methods: Schizophrenic inpatients receiving long-term antipsychotic treatment were assessed using the Abnormal Involuntary Movement Scale, and only patients who were either free of any abnormal involuntary movement (non-TD group) or who demonstrated persistent TD (TD group) were enrolled. Genotyping of six tagging single nucleus polymorphisms (SNPs) in the melatonin receptor genes (MRNR1A, MTNR1B) was then performed for each subject.
Results: Four hundred and eighteen inpatients (TD=256, non-TD=162) fitted the study criteria and underwent TD assessment and genotyping. Individual haplotype analysis showed that the haplotype ATG was significantly associated with non-TD (permutation P=0.037), and the association was also found to be significant by global haplotype analyses (permutation P=0.045).
Conclusions: Our results indicated a significant association between the haplotype ATG in the MTNR1A gene and non-TD. Further replication in other countries or other populations is indicated.