What you carry at this position in your DNA and what research says about it.
Skin Cancer Risk: 10/10 evidence, 33 publications.
You're viewing every possible genotype for this variant.
None of these is your result. Use the genotype toggle to compare them, then sign up and upload your DNA to see which one is yours.
Sample genotype (not yours): C/C
Typical Skin Cancer Risk
Two copies of the common allele are associated with standard baseline risks for skin cancers and typical pigmentation.
What this genotype means: Typical baseline risk for melanoma; Standard skin sensitivity to sun exposure; Typical response to anesthetic medications.
Sample genotype (not yours): C/T
Increased Skin Cancer Risk
Carrying one copy of the variant allele is linked to a higher risk of melanoma and increased sun sensitivity.
What this genotype means: Elevated risk of melanoma and basal cell carcinoma; Increased sensitivity to sunburns; Likely carrier of the red hair trait.
Sample genotype (not yours): T/T
Significantly Higher Skin Cancer Risk
Two copies of the variant allele greatly increase skin cancer risk, sun sensitivity, and the likelihood of red hair.
What this genotype means: Highly elevated risk of melanoma and other skin cancers; Very high sensitivity to sun exposure and sunburns; Altered sensitivity to local and general anesthetics.
Gene function and biological role
Gene Function: The MC1R gene encodes the melanocortin 1 receptor, which plays a critical role in controlling human pigmentation [1]. This receptor sits on the surface of melanocytes, the cells responsible for producing melanin in the skin and hair [1]. When activated, the receptor triggers a cascade that produces eumelanin, a dark brown or black pigment that protects the skin from ultraviolet radiation [1]. Mutations that impair the function of this receptor lead to a shift toward producing pheomelanin, a red or yellow pigment that is less effective at blocking UV rays [1]. Consequently, variations in this gene are major determinants of sun sensitivity, freckling, and skin cancer susceptibility [2].
Variant Impact: The rs1805007 variant, also known as Arg151Cys or R151C, is a missense mutation in the MC1R gene that alters a key amino acid in the receptor protein [1]. This specific change significantly reduces the receptor's ability to stimulate protective eumelanin production [1]. As a result, the body produces higher levels of the red-yellow pigment pheomelanin, which is associated with lighter skin, freckles, and red hair [1]. Beyond pigmentation, this structural alteration in the receptor has been shown to influence how the nervous system interacts with certain types of pain medications and anesthetics [2].
Key Insight: Carrying two copies of this variant can increase the likelihood of having red hair by up to twenty-fold and may alter how your body responds to dental numbing agents and general anesthesia.
Location: MC1R. Chromosome 16 · 16q24.3 · 89.9 Mb
Estimated prevalence by population
Global 91.0%; European 85.7%; African 97.1%; East Asian 99.8%; South Asian 99.0%; Americas 96.7%; Ashkenazi 85.6%; Finnish 86.5%; Middle Eastern 98.6%; Amish 90.2%.
Estimated CC genotype frequency.
Global 8.7%; European 13.7%; African 2.9%; East Asian 0.2%; South Asian 1.0%; Americas 3.3%; Ashkenazi 13.8%; Finnish 13.0%; Middle Eastern 1.4%; Amish 9.6%.
Estimated CT genotype frequency.
Global 0.3%; European 0.5%; African < 0.1%; East Asian < 0.1%; South Asian < 0.1%; Americas < 0.1%; Ashkenazi 0.6%; Finnish 0.5%; Middle Eastern < 0.1%; Amish 0.3%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cancer & Oncology
Skin Cancer
Melanoma. Evidence: 10/10. Source: PMID 32341527. Typical Risk.
Basal Cell Carcinoma. Evidence: 10/10. Source: PMID 21700618. Typical Risk.
Organ Systems
Pigmentation & Appearance
Red Hair Likelihood. Evidence: 10/10. Source: PMID 17952075. Typical Likelihood.
Sun Sensitivity. Evidence: 8/10. Source: PMID 17952075. Typical Sensitivity.
Pharmacogenomics
Anesthesia Response
Anesthetic Response. Evidence: 6/10. Typical Response.
Showing effects for C/T genotype
Melanoma. Evidence: 10/10. Source: PMID 32341527. Increased Risk.
Basal Cell Carcinoma. Evidence: 10/10. Source: PMID 21700618. Increased Risk.
Red Hair Likelihood. Evidence: 10/10. Source: PMID 17952075. Slightly Increased.
Sun Sensitivity. Evidence: 8/10. Source: PMID 17952075. Increased Sensitivity.
Showing effects for T/T genotype
Melanoma. Evidence: 10/10. Source: PMID 32341527. Highly Increased Risk.
Basal Cell Carcinoma. Evidence: 10/10. Source: PMID 21700618. Highly Increased Risk.
Red Hair Likelihood. Evidence: 10/10. Source: PMID 17952075. 13-20x Higher.
Sun Sensitivity. Evidence: 8/10. Source: PMID 17952075. High Sensitivity.
Anesthetic Response. Evidence: 6/10. Altered Response.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Having two copies of the C allele means the melanocortin 1 receptor functions normally to produce protective dark melanin [1]. This normal receptor activity helps shield skin cells from ultraviolet radiation damage, maintaining a standard baseline risk for melanoma and other skin cancers [1]. Individuals with this genotype typically have standard skin sensitivity to the sun and are less likely to have natural red hair [1]. There are no expected alterations in response to dental numbing agents or general anesthesia associated with this genetic marker [2]. Standard sun protection practices remain recommended to maintain skin health.
Typical baseline risk for melanoma; Standard skin sensitivity to sun exposure; Typical response to anesthetic medications.
Sample genotype: CT (Heterozygous)
Carrying one copy of the T allele reduces the overall efficiency of the melanocortin 1 receptor in producing protective dark melanin [1]. This reduction in protective pigment leads to an increased susceptibility to ultraviolet radiation damage from the sun [1]. Clinical studies have shown that carriers of this single variant have a significantly higher risk of developing melanoma and other skin cancers compared to non-carriers [2]. While one copy of this variant is usually not enough to cause red hair on its own, it still contributes to lighter skin tones and increased freckling [1]. Response to local and general anesthetics remains typical, as one functioning copy of the receptor is generally sufficient to maintain normal signaling pathways.
Elevated risk of melanoma and basal cell carcinoma; Increased sensitivity to sunburns; Likely carrier of the red hair trait.
Sample genotype: TT (Homozygous)
Having two copies of the T allele severely limits the function of the melanocortin 1 receptor, causing the body to produce red-yellow pheomelanin instead of protective dark eumelanin [1]. This pigment shift dramatically increases the risk of developing melanoma, basal cell carcinoma, and squamous cell carcinoma [2]. Individuals with this genotype are highly likely to have natural red hair, fair skin, and a high sensitivity to sun exposure [1]. Furthermore, this genotype is associated with an altered response to certain medications, including an increased sensitivity to some dental analgesics and a decreased sensitivity to inhaled general anesthetics [2]. Extra precautions against ultraviolet radiation, such as regular skin checks and consistent sunscreen use, are highly relevant for individuals with this genetic profile.
Highly elevated risk of melanoma and other skin cancers; Very high sensitivity to sun exposure and sunburns; Altered sensitivity to local and general anesthetics.
Variants with shared genetic architecture
rs1805008 · MC1R Gene · Chr 16 · Melanoma and Skin Cancer Risk
rs2228479 · MC1R Gene · Chr 16 · Skin and Hair Pigmentation
rs1805005 · MC1R Gene · Chr 16 · Melanoma Risk
Genetic determinants of hair, eye and skin pigmentation in Europeans.
Content updated August 2026.
ReadYourDNA provides educational interpretation of DNA data you already have. It is not diagnostic, not a substitute for professional medical advice, diagnosis, or treatment, and is not intended to diagnose, treat, cure, or prevent any disease. Talk to a clinician before acting on any result.
Raw DNA Data Reports for 23andMe & AncestryDNA · About ReadYourDNA · FAQ · Methodology & Science · Pricing · Support and complaints · Legal & Contact · Health Traits · Pharmacogenomics · Carrier Status · Variant Explorer · The Human Karyotype · Privacy Policy · Terms of Service · Accessibility · Consumer Health Data Privacy · Your Privacy Choices · Editorial Standards · Your Data, Checkable · Sample Report · ReadYourDNA and Promethease compared · What is inside a 23andMe raw data file · What is inside an AncestryDNA raw data file · What a chatbot can and cannot do with your raw DNA file · Where a raw DNA file can still be uploaded in 2026
Written, maintained and operated by Martin Pechhacker, sole proprietor, Vienna, Austria. Trade register GISA 40064420. support@readyourdna.com