No genetic association between A118G polymorphism of μ-opioid receptor gene and schizophrenia and bipolar disorders

BACKGROUND: Schizophrenia (SZ) and bipolar disorder (BD) are chronic and multifactorial psychiatric disorders that might be affected by different genes in combination with environmental factors. There is evidence of association between polymorphisms of μ-opioid receptor gene (OPRM1) with these disorders. OBJECTIVES: The aim of this study was to investigate the genetic association between OPRM1 A118G SNP in SZ and BD patients in comparison with healthy controls (HCs). MATERIALS AND METHODS: One single-nucleotide polymorphism in OPRM1 was genotyped using TaqMan real-time PCR assay in 203 SZ and BD patients and 389 HCs. RESULTS: There was no statistically significant difference in genotypic and allelic frequencies of OPRM1 A118G SNP between HCs and SZ/BD patients. CONCLUSIONS: To find the underlying genetic factors associated with these complex disorders, further studies need to be conducted using larger sample size, different genetic populations, and different gene variations.