OPRM1
Opioid Receptor Mu 1
Gene Number: 4988
Location: 6q25.2
Key Functions: Pain regulation, endorphin signaling, opioid response, reward processing
OPRM1 produces the mu-opioid receptor, a protein activated by the body’s natural opioids, including endorphins, and by medicines such as morphine. This receptor helps regulate pain relief and contributes to the brain’s reward system [R].
Explore your genotypes below, or visit COMT and neurotransmitter metabolism to understand another pathway involved in pain processing.
SNP ID | Your Genotype | Alt Allele | Interpretation |
|---|---|---|---|
rs1799971 | Analyze your DNA to see your genotype | G | Analyze your DNA to see a personalized result. |
rs9479757 | Analyze your DNA to see your genotype | A | Analyze your DNA to see a personalized result. |
rs1799971 — A118G and Opioid Pain Relief
AA – Normal risk; baseline for pain sensitivity and addiction phenotypes [R].
AG – Asn/Asp. One G allele. Linked to somewhat higher opioid requirements for pain relief in some surgical settings [R].
GG – Asp/Asp. Two G alleles. Also linked to higher postoperative opioid requirements, although the effect is not consistently proportional to the number of G alleles [R].
The CPIC evidence review describes approximately 10% higher postoperative morphine requirements in some studies of people carrying at least one G allele. This is a study finding—not a recommended dose adjustment or a percentage increase in pain sensitivity [R].
Functional effect: A118G changes asparagine to aspartate at position 40 of the receptor. It removes a site where a sugar group can attach, and laboratory studies have found reduced receptor expression. This can influence receptor availability and opioid signaling [R].
rs9479757 — Receptor Processing and Dependence Severity
GG — Common genotype. Linked to greater heroin-dependence severity than AG in a study of Han Chinese men already experiencing heroin dependence [R].
AG — One A allele. Linked to milder dependence severity than GG in that study [R].
AA — Two A alleles. Evidence is insufficient to assign a reliable, separate severity estimate [R].
These findings concern severity among people with established dependence, rather than the chance of developing dependence.
What About Alcohol and Naltrexone?
Earlier research suggested that rs1799971 G-allele carriers might respond better to naltrexone for alcohol dependence. However, a later meta-analysis of seven randomized controlled trials did not confirm a reliable difference after accounting for multiple comparisons. Describing naltrexone as “twice as effective” for AG is therefore too definite [R, R].
Medication context: CPIC provides no opioid-dosing recommendations based on OPRM1 genotype. Treatment should follow your clinical response and prescriber’s guidance [R].
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