Genomic variations and transcriptional regulation of the human μ-opioid receptor gene

In conclusion, transcriptional regulation of MOR1 is modified by two genetic variations at positions −554 and −1320 of the μ-opioid receptor promoter. Individuals presenting these variations may have an altered level of MOR expression. A possible association of these genomic variants on efficacy and side effects of opioid treatment in different ethnic groups has to be elucidated.