No association found between the type 1 sigma receptor gene polymorphisms and methamphetamine abuse in the Japanese population: A collaborative study by the Japanese genetics initiative for drug abuse

It has been suggested that individual genetic factors are involved in susceptibility to drug dependence and the manifestation of drug-induced psychosis. The aim of this study was to examine the relation between methamphetamine abusers/psychosis and the type 1 sigma receptor gene polymorphisms. Subjects comprised 143 MAP abusers and 181 healthy controls. Two polymorphisms in the type 1 sigma receptor gene, GC-241-240TT and A61C (Gln2Pro), were examined in the present study. No significant differences were observed in either polymorphism between healthy controls and MAP abusers/psychosis. In the subgroup analyses, the rate of CC genotype of A61C tended to be higher in MAP patients who had experienced spontaneous relapse without MAP use than in those who had not (P = .06, OR = 3.02 95% CI = 0.92-9.92). However, the level of this significant trend did not remain after the Bonferroni's multiple correction. This study suggests that type 1 sigma receptor gene is unlikely to play a major role in substance abuse liability and/or the development of MAP psychosis.