D3 Receptor Gene Variant and Tardive Dyskinesia in Schizophrenic Patients

Nam, Jong Won; Lee, Min Soo

Abstract

Tardive dyskinesia(TD)is one of the serious side effects caused by long-term treatment with neuroleptic medication. It has been known that dopamine D3 receptors are mainly located on the postsynaptic membrane where they display an inhibitory action on locomotor activity. In this study, we investigated the genetic variation of the dopamine D3 receptor gene(DRD3)as a putative risk factor for TD in schizophrenic patients receiving long-term antipsychotic medication. Fifty schizophrenic patients previously treated neuroleptic medication, were assessed for TD severity using Extrapyramidal Symptom Rating Scale(ESRS) Genomic DNA was amplified by PCR and Digestion with MluI yield two bands of 111bp and 47bp in all subjects. Subjects with a 304bp band were classified a1a1, those with 206bp and 98bp bands a2a2, and those with all five bands a1a2. The allelic distributions in TD patients and non-TD patients were not significantly different(x2=.852, df=2, p=.653) The number of each genotype observed in the schizophrenic group, did not differ significantly from the values expected according to Hardy-Weinberg equilibrium(x2=.29, df=2) This result did not support that dopamine D3 receptor gene variant were susceptible to TD in schizophrenic patients. The role of dopamine D3 receptors as a putative risk factors of TD may therefore be less important than previously thought.