Possible association between G-protein beta 3 subunit C825T polymorphism and antipsychotic-induced restless legs syndrome in schizophrenia

Abstract

Objective: The incidence of restless legs syndrome (RLS) is presumed to be higher among people with schizophrenia who take antipsychotic medication, most of which blocks the dopamine D2 receptor. The purpose of this study was to determine whether the G-protein beta(3) subunit (GNB3) C825T polymorphism is associated with antipsychotic-induced RLS in schizophrenia. Methods: We examined 178 Korean patients with schizophrenia. All of the subjects were evaluated using the diagnostic criteria of the International Restless Legs Syndrome Study Group and the International Restless Legs Scale. Genotyping was performed for the C825T polymorphism in the GNB3 gene. Results: The genotype distribution did not differ significantly between antipsychotic-induced RLS patients and patients who had no-RLS symptoms (chi(2) = 4.30, p = 0.116). The genotypes of the C825T single-nucleotide polymorphism (SNP) were classified into two groups: C+ (CC and CT genotypes) and C- (TT genotype). The presence of the C allele (C+) was associated with an increased likelihood of RLS (chi(2) = 4.14, p = 0.042; odds ratio = 2.56, 95% confidence interval = 1.02-6.47). Conclusions: These results suggest that the GNB3 C825T SNP is associated with RLS in schizophrenia. However, confirming this association requires future larger scale studies in which the effects of medication are strictly controlled.