The promoter SNP rs569356 is located ∼2 Kb upstream to the transcription start site and is in high LD with SNP rs1042114 (80G>T, Phe27Cys). Functional characterization of SNP rs569356 (A>G) with luciferase reporter gene assay in HEK293 cells demonstrated that the G-allele can enhance OPRD1 promoter activity under basal conditions. Electrophoretic mobility shift assay (EMSA) with human brain nuclear proteins showed enhanced DNA protein binding of the probe with the G-allele (Zhang et al. 2010).
