rs1799971

A SNP in the OPRM1 gene on chromosome 6. Its most notable genotype is G;G: more pain

Gene
OPRM1
Location
Chr 6154,039,662 (GRCh38)
Highest magnitude
2.6Worth knowing
Tested on
23andMe, AncestryDNA, FamilyTreeDNA
Minor allele frequency
19%

Genotypes

As shown in 23andMe and AncestryDNA files.

  1. A;AGoodnormalTypical · 0.066% of people
  2. A;GBadstronger cravings for alcohol. if alcoholic, naltrexone treatment 2x more successfulWorth knowing · 2.528% of people
  3. G;GMost notableBadmore painWorth knowing · 2.67% of people

On SNPedia: (A;A), (A;G), (G;G). Magnitude rates how notable a genotype is from 0 to 10, not how risky it is.

Frequency

Share of each genotype in 11 HapMap populations.

  • AverageA;A 66% A;G 28% G;G 7%
  • European ancestry (Utah)A;A 71% A;G 27% G;G 2%
  • Han Chinese (Beijing)A;A 40% A;G 47% G;G 12%
  • Japanese (Tokyo)A;A 29% A;G 48% G;G 23%
  • Yoruba (Nigeria)A;A 100% A;G 0% G;G 0%
  • African ancestry (Southwest US)A;A 93% A;G 7% G;G 0%
  • Chinese (Denver)A;A 32% A;G 52% G;G 17%
  • Gujarati IndianA;A 31% A;G 55% G;G 14%
  • Luhya (Kenya)A;A 98% A;G 2% G;G 0%
  • Mexican ancestry (Los Angeles)A;A 64% A;G 33% G;G 3%
  • Maasai (Kenya)A;A 94% A;G 6% G;G 0%
  • TuscanA;A 70% A;G 28% G;G 2%

Notes

From SNPedia

Show notes, about 600 words

The rs1799971(G) allele in exon 1 of the mu opioid receptor OPRM1 gene causes the normal amino acid at residue 40, asparagine (Asn), to be replaced by aspartic acid (Asp). In the literature this SNP is also known as A118G, N40D, or Asn40Asp. Carriers of at least one rs1799971(G) allele appear to have stronger cravings for alcohol than carriers of two rs1799971(A) alleles, and are thus hypothesized to be more at higher risk for alcoholism. However, subsequent research results are mixed, and there are other studies both agreeing or disagreeing with this finding PMID 15525999, PMID 9399694, PMID 12960749 Among 200+ alcoholics treated with naltrexone, rs1799971(G) carriers receiving the drug (even without behavioral intervention) had an increased percentage of days abstinent (p = .07) and a decreased percentage of heavy drinking days (p = .04) if treated with naltrexone vs. placebo, whereas rs1799971(A;A) homozygotes showed no medication differences. Upon treatment with naltrexone, 87% of rs1799971(G) carriers had a good clinical outcome, compared with only 55% of individuals with the (A;A) genotype (odds ratio, 5.75, CI: 1.88-17.54) This SNP may also influence the response to opioids such as heroin, codeine or morphine. A 2015 meta-analysis (totaling 5,902 patients) concluded that the carriers of a rs1799971(G) allele consumed more opioids for analgesia (SMD = -0.17, CI:-0.25, -0.10, p C polymorphism and intermediate type 2 diabetes phenotypes: results from the Quebec Family Study (QFS). Genetic susceptibility to heroin addiction: a candidate gene association study. Gene and gene by sex associations with initial sensitivity to nicotine in nonsmokers. Polymorphisms affecting gene transcription and mRNA processing in pharmacogenetic candidate genes: detection through allelic expression imbalance in human target tissues. Bidirectional translational research: Progress in understanding addictive diseases. OPRM1 gene is associated with BMI in Uyghur population. OPRM1 Asn40Asp predicts response to naltrexone treatment: a haplotype-based approach. Expansion of the human mu-opioid receptor gene architecture: novel functional variants. Now or Later? An fMRI study of the effects of endogenous opioid blockade on a decision-making network. Candidate genes for cannabis use disorders: findings, challenges and directions. Do genetic predictors of pain sensitivity associate with persistent widespread pain? PCA-based bootstrap confidence interval tests for gene-disease association involving multiple SNPs. Association of mu-opioid receptor variants and response to citalopram treatment in major depressive disorder. OPRM1 gene variants modulate amphetamine-induced euphoria in humans. Effect sizes in experimental pain produced by gender, genetic variants and sensitization procedures. Variation in OPRM1 and risk of suicidal behavior in drug-dependent individuals. Possible Association Between OPRM1 Genetic Variance at the 118 Locus and Alcohol Dependence in a Large Treatment Sample: Relationship to Alcohol Dependence Symptoms. Association of polymorphisms of the mu opioid receptor gene with the severity of HIV infection and response to HIV treatment. Pharmacogenetically driven treatments for alcoholism: are we there yet? Naltrexone Treatment Response

G;G

blog.23andme.com associated with needing more morphine for pain relief after surgery and heightened responses to social rejection. stronger cravings for alcohol; if alcoholic, naltrexone treatment 2x more successful

Source and license

Adapted from rs1799971 on SNPedia, using a snapshot taken October 16, 2026. SNPedia content is shared under CC BY-NC-SA 3.0 US, and this page is shared under the same license.

SNPedia is a community-edited wiki. Its entries can be incomplete, out of date or wrong, and nothing here is a diagnosis or medical advice. Magnitude is a community rating of how interesting a genotype is, not a risk score.