rs1805007

A SNP in the MC1R gene on chromosome 16. Its most notable genotype is T;T: increased response to anesthetics; 13-20x higher likelihood of red hair; increased risk of melanoma

Gene
MC1R
Location
Chr 1689,919,709 (GRCh38)
Highest magnitude
3.2Important
Tested on
23andMe, AncestryDNA
Minor allele frequency
3%

Genotypes

As shown in 23andMe and AncestryDNA files.

  1. C;CGoodnormal riskTypical · 0.095% of people
  2. C;TBadCarrier of a red hair associated variant; higher risk of melanomaWorth knowing · 2.75% of people
  3. T;TMost notableBadincreased response to anesthetics; 13-20x higher likelihood of red hair; increased risk of melanomaImportant · 3.2<1% of people

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

Frequency

Share of each genotype in 8 HapMap populations.

  • AverageC;C 95% C;T 5% T;T <1%
  • European ancestry (Utah)C;C 77% C;T 22% T;T <1%
  • Han Chinese (Beijing)C;C 99% C;T 2% T;T 0%
  • Japanese (Tokyo)C;C 100% C;T 0% T;T 0%
  • Yoruba (Nigeria)C;C 100% C;T 0% T;T 0%
  • African ancestry (Southwest US)C;C 97% C;T 4% T;T 0%
  • Gujarati IndianC;C 99% C;T 1% T;T 0%
  • Mexican ancestry (Los Angeles)C;C 98% C;T 2% T;T 0%
  • TuscanC;C 94% C;T 6% T;T 0%

Other MC1R SNPs

All MC1R SNPs

Genosets

Genosets combine several genotypes. Twofold checks them in your report.

Notes

From SNPedia

Show notes, about 230 words

rs1805007, known as Arg151Cys or R151C, one of several SNPs in the MC1R gene associated with red hair color (redheads), and in redheaded females. rs1805007 has been linked to being more responsive to the analgesics pentazocine, nalbuphine, and butorphanol, often used by dentists PMID 9571181, PMID 12663858, PMID 18488028. However, redheads carrying this mutation have also demonstrated decreased responsiveness to the inhaled general anesthesia desflurane PMID 15277908. The allele associated with red hair and increased anesthetic response (when homozygous) is rs1805007(T); the wild-type, more common allele is rs1805007(C). Note that in the studies of anesthetic response, having a single rs1805007(T) allele was equivalent to having none, because in both cases, in the absence of mutations elsewhere, the person still has a functioning MC1R receptor. The risk allele has also been reported in several studies to be associated with increased risk for melanoma. For example, an odds ratio of 2.94 (CI: 1.04-8.31) has been reported for an Italian population , and similarly an odds ratio of 2.9 has been reported for a Polish population . Blog entry about designing melanocortin analogs specific to these genotypes. See also OMIM 155555.0004 Freckling

C;T

this genotype raises the melanoma risk 42% (95% CI, 15–76%) higher than that among persons not carrying a similar allele.

References

Source and license

Adapted from rs1805007 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.