MC1R rs4268748: Genetics, Sun Damage, and Photoaging
The genetic variant rs4268748 is a non-coding single nucleotide polymorphism located in the 16q24.3 region adjacent to and within the regulatory landscape of the MC1R gene. Large-scale genome-wide association studies have identified it as a significant marker for human skin color variation, solar lentigines, and perceived photo-age acceleration. While it tags key pigmentation phenotypes in European populations, its biological effects largely reflect linkage disequilibrium with functional MC1R alleles.
What each genotype means
Typical pigmentation profile
This genotype is associated with the common, non-variant form of the MC1R regulatory region. Research indicates this profile is typically linked to standard skin and hair pigmentation patterns rather than the increased sun sensitivity often observed with MC1R variants.
This is the most common genotype in many global populations, particularly those with higher levels of eumelanin production.
Intermediate sun sensitivity
Carrying one copy of the C allele at this position is associated with a moderate influence on skin pigmentation and photo-aging traits. Studies suggest that individuals with this genotype may have a slightly higher predisposition to sun-related skin changes compared to those without the variant, though the effect is generally less pronounced than in those with two copies.
This heterozygous genotype is found in a significant portion of European populations, reflecting the common occurrence of the C allele.
Increased sun sensitivity
This genotype is associated with a higher likelihood of sun-related skin changes, including solar lentigines and accelerated photo-aging. Research indicates that this variant, located near the MC1R gene, contributes to the genetic variance in skin pattern damage and sun sensitivity; you may wish to prioritize consistent sun protection and regular skin health monitoring.
The C allele has a minor allele frequency of approximately 0.35 in European populations, making this homozygous genotype relatively common.
Genomic Context and the MC1R Locus
The single nucleotide polymorphism rs4268748 is located on chromosome 16 at band 16q24.3, mapping to an intronic or regulatory region adjacent to the melanocortin 1 receptor (MC1R) gene, occasionally annotated within the DEF8/MC1R locus. MC1R encodes a seven-transmembrane G-protein-coupled receptor that acts as the master switch in melanocytes, dictating whether these cells produce photoprotective dark brown/black eumelanin or lighter, red/yellow, UV-sensitizing pheomelanin. As a non-coding variant, rs4268748 is not known to alter the amino acid sequence of the receptor itself. Instead, functional and genomic mapping suggest it operates either as a regulatory modifier of local gene expression or, more prominently, as a genetic tag in high linkage disequilibrium (LD) with well-described functional missense variants within the MC1R coding sequence.
Research Associations with Photoaging and Skin Damage
In human phenotypic research, rs4268748 has emerged as a top-associated marker in genome-wide association studies (GWAS) exploring pigmentation, facial sun damage, and premature photoaging. Quantitative studies of skin pigmentation, including large-scale European cohorts like the Rotterdam Study, pinpointed rs4268748 as one of the strongest single-marker signals for baseline skin tone and ultraviolet susceptibility. Carriers of the effect allele (C) frequently display increased vulnerability to actinic damage, solar lentigines (sun spots), and accelerated perceived facial age. However, researchers have demonstrated that when known high-penetrance MC1R coding mutations (such as R151C, R160W, and D294H) are directly factored into statistical models, they explain the vast majority of the variance captured by rs4268748. This confirms that while the association with severe facial sun damage is statistically robust, rs4268748 functions primarily as a proxy for diminished-function MC1R haplotypes in European genomes.
Ancestry and Population Diversity
The distribution and phenotypic relevance of rs4268748 vary significantly across human populations. In European cohorts, the minor C allele reaches a frequency of approximately 23% to 35%, tracking closely with alleles that diminish eumelanin production and increase sun sensitivity. Intriguingly, genomic surveys in East Asian populations demonstrate that the C allele is also common (reaching approximately 27% to 28% in 1000 Genomes Project samples), yet association studies reveal no nominal link to skin pigmentation variation or photoaging in East Asians. This stark difference underscores the principle of linkage disequilibrium: the classical loss-of-function MC1R missense mutations linked to rs4268748 in Europe are virtually absent in East Asia, meaning the non-coding variant loses its proxy association across different ancestral genetic backgrounds.
What You Can and Cannot Do with This Information
Finding your genotype for rs4268748 provides insight into statistical population-level predispositions, but it is not a direct diagnostic test or clinical prognosis. A carrier status for the risk-associated allele indicates a higher statistical likelihood of fair skin, reduced UV buffering capacity, and heightened propensity for sun-induced skin aging and solar lentigines. It does not guarantee severe premature aging, nor does an ancestral or non-risk genotype confer absolute immunity to ultraviolet damage. Regardless of your genotype, standard dermatological precautions—such as consistent broad-spectrum sun protection, avoidance of peak UV hours, and routine professional skin evaluations—remain universally necessary for maintaining skin health and minimizing photoaging.
How common is this variant?
The minor C allele has a frequency of approximately 0.23 to 0.35 in European populations, where it correlates with lighter skin tone and photoaging. While the allele is also present at roughly 0.27 to 0.28 in East Asian ancestries, it is uncoupled from pigmentation traits there due to differences in ancestral linkage disequilibrium.
Frequently asked questions
What is rs4268748?
rs4268748 is a single nucleotide polymorphism located in the regulatory region of chromosome 16 near the MC1R gene. In scientific literature, it is widely recognized as a genetic marker associated with variation in human skin pigmentation, sun sensitivity, and facial photoaging.
Does having the rs4268748 risk allele mean I will develop severe wrinkles and sun spots?
No, it does not guarantee skin damage. The variant only indicates a statistical predisposition to higher ultraviolet susceptibility and solar damage based on population studies. Actual skin aging depends heavily on lifestyle factors, cumulative sun exposure, and consistent sunscreen usage.
Why does rs4268748 affect Europeans differently than other ancestral groups?
rs4268748 is primarily a tag variant rather than a direct functional mutation. In European populations, it sits on the same stretch of DNA as specific loss-of-function MC1R mutations, whereas in other groups—such as East Asians—those underlying coding variants are absent, decoupling rs4268748 from skin traits.
Does this genetic variant increase the risk of skin cancer?
While the MC1R gene itself is heavily implicated in skin cancer risk through its role in UV photoprotection, rs4268748 is primarily evaluated in research as a marker for pigmentation and photoaging. Any individual with elevated sun sensitivity or fair skin should maintain regular skin cancer screenings with a dermatologist.
Sources & further reading
Educational information only, last refreshed 9/7/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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The p.Arg163Gln variant in MC1R is associated with red hair, fair skin, and increased melanoma risk.
This missense variant (p.Arg142His) is a well-established, highly penetrant allele associated with red hair color and fair skin pigmentation.
This missense variant (p.Arg160Trp) is a primary genetic determinant of red hair color, pale skin, and increased freckling in European populations.
The Val60Leu missense variant in MC1R is a well-documented factor contributing to the red hair, fair skin, and freckling phenotype.
A rare variant associated with lighter skin pigmentation in specific populations.
Asp294His coding substitution in the MC1R gene associated with red hair, skin sun-sensitivity, and melanoma risk.