What you carry at this position in your DNA and what research says about it.
Skin Cancer Risk: 10/10 evidence, 44 publications.
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Sample genotype (not yours): C/C
Significantly Lower Skin Cancer Risk
Two copies of the ancestral C allele provide dark hair, darker skin pigmentation, and robust protection against skin cancers. This genotype is highly common in non-European populations.
What this genotype means: Significantly lower risk of melanoma and other skin cancers; Darker skin pigmentation and higher likelihood of dark hair; Highly efficient natural UV protection.
Sample genotype (not yours): C/G
Lower Skin Cancer Risk
Carrying one copy of the ancestral C allele provides substantial protection against skin cancers and is linked to darker hair. This genotype is relatively rare in Europeans but common in admixed populations.
What this genotype means: Reduced risk of melanoma and basal cell carcinoma compared to G/G; Increased likelihood of darker hair and skin; Moderate natural UV protection.
Sample genotype (not yours): G/G
Increased Skin Cancer Risk
Two copies of the G allele lead to light skin, light hair, and a significantly higher risk of skin cancers and rosacea. This genotype is extremely common in European populations.
What this genotype means: Significantly higher risk of melanoma, basal cell carcinoma, and actinic keratosis; Lighter skin pigmentation and higher sensitivity to sun exposure; Increased susceptibility to rosacea.
Gene function and biological role
Gene Function: The SLC45A2 gene encodes the membrane-associated transporter protein, which plays a critical role in melanin synthesis [1]. This protein helps regulate the pH of melanosomes, the cellular compartments where pigment is produced [1]. Proper pH is essential for the optimal functioning of tyrosinase, the key enzyme responsible for skin, hair, and eye pigmentation [1]. Variations in this gene can significantly alter the type and amount of melanin produced, leading to natural variations in human skin tones [2]. In rare cases, severe mutations in SLC45A2 can cause oculocutaneous albinism type 4, a condition characterized by a near-total lack of pigment [3].
Variant Impact: This variant, rs16891982, is a missense mutation that changes the amino acid at position 374 from leucine to phenylalanine [1]. This single amino acid swap alters the transporter protein's structure, leading to an acidic environment inside melanosomes that impairs pigment production [2]. Consequently, the variant allele is one of the strongest genetic determinants of light skin and blonde or red hair in European populations [4]. Conversely, the ancestral reference allele maintains optimal pigment production, resulting in darker skin and hair [4]. This change in pigmentation directly influences how much ultraviolet radiation is absorbed, thereby modifying the risk of developing skin cancers [5].
Key Insight: This single genetic letter change is one of the primary reasons for the light skin pigmentation characteristic of European populations. While light skin helps synthesize vitamin D in low-sunlight environments, it significantly increases susceptibility to UV-induced skin cancers.
Location: SLC45A2. Chromosome 5 · 5p13.2 · 34.0 Mb
Origin Story: The light-skin variant underwent intense positive selection as early humans migrated into northern Europe, where weaker sunlight made depigmentation advantageous for synthesizing vitamin D, despite the trade-off of higher skin cancer risk.
Estimated prevalence by population
Global 27.6%; European 0.1%; African 70.1%; East Asian 98.9%; South Asian 81.2%; Americas 20.2%; Ashkenazi 0.8%; Finnish < 0.1%; Middle Eastern 28.2%; Amish < 0.1%.
Estimated CC genotype frequency.
Global 17.4%; European 7.3%; African 27.3%; East Asian 1.1%; South Asian 17.8%; Americas 49.5%; Ashkenazi 16.0%; Finnish 3.1%; Middle Eastern 49.8%; Amish 2.0%.
Estimated CG genotype frequency.
Global 55.1%; European 92.5%; African 2.7%; East Asian < 0.1%; South Asian 1.0%; Americas 30.3%; Ashkenazi 83.3%; Finnish 96.8%; Middle Eastern 22.0%; Amish 98.0%.
Estimated GG genotype frequency.
Showing effects for C/C genotype
Cancer & Oncology
Skin Cancer
Melanoma. Evidence: 10/10. Source: PMID 19710684. ~68% Lower Risk.
Basal Cell Carcinoma. Evidence: 10/10. Source: PMID 38182794. Typical Risk.
Actinic Keratosis. Evidence: 10/10. Source: PMID 35449187. Typical Risk.
Organ Systems
Pigmentation & Appearance
Hair Color. Evidence: 10/10. Source: PMID 18806926. 7x More Black Hair.
Skin Pigmentation. Evidence: 10/10. Source: PMID 25963972. Darker Skin.
Skin & Hair Conditions
Rosacea. Evidence: 10/10. Source: PMID 29771307. Typical Risk.
Showing effects for C/G genotype
Melanoma. Evidence: 10/10. Source: PMID 19710684. ~65% Lower Risk.
Skin Pigmentation. Evidence: 10/10. Source: PMID 25963972. Medium/Darker Skin.
Showing effects for G/G genotype
Melanoma. Evidence: 10/10. Source: PMID 19710684. ~3x Higher Risk.
Basal Cell Carcinoma. Evidence: 10/10. Source: PMID 38182794. ~1.56x Higher Risk.
Actinic Keratosis. Evidence: 10/10. Source: PMID 35449187. ~1.92x Higher Risk.
Hair Color. Evidence: 10/10. Source: PMID 18806926. Lighter/Blonde/Red.
Skin Pigmentation. Evidence: 10/10. Source: PMID 25963972. Lighter Skin.
Rosacea. Evidence: 10/10. Source: PMID 29771307. Increased Risk.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Carrying two copies of the C allele ensures optimal functioning of the SLC45A2 pigment transporter [1]. This leads to efficient melanin production, resulting in darker skin, dark eyes, and a significantly higher likelihood of black hair [2]. The increased melanin acts as a natural sunscreen, absorbing harmful ultraviolet radiation and protecting skin cells from DNA damage [3]. Consequently, this genotype is associated with a roughly 65% to 70% lower risk of developing cutaneous melanoma compared to the G/G genotype [4]. It also provides strong protection against other keratinocyte cancers, including basal cell carcinoma and squamous cell carcinoma [5]. This genotype is the ancestral state and is nearly universal in African, East Asian, and South Asian populations [1]. Individuals with this genetic profile typically have high natural sun tolerance.
Significantly lower risk of melanoma and other skin cancers; Darker skin pigmentation and higher likelihood of dark hair; Highly efficient natural UV protection.
Sample genotype: CG (Heterozygous)
Having one copy of the C allele and one copy of the G allele results in an intermediate pigmentation phenotype, though it strongly leans toward darker hair and skin compared to G/G [1]. This genotype is associated with a 7-fold increased likelihood of having black hair in European populations compared to those with G/G [2]. Crucially, the presence of a single C allele is highly protective against skin malignancies [3]. Research indicates that individuals with this heterozygous genotype have an approximately 65% lower risk of developing cutaneous melanoma compared to those with the G/G genotype [4]. It also offers protection against basal cell carcinoma and actinic keratosis [5]. This genotype represents a genetic bridge between ancestral dark pigmentation and derived light pigmentation [6]. It is common in populations with mixed ancestry.
Reduced risk of melanoma and basal cell carcinoma compared to G/G; Increased likelihood of darker hair and skin; Moderate natural UV protection.
Sample genotype: GG (Homozygous)
Carrying two copies of the G allele causes a structural change in the SLC45A2 protein that reduces melanin synthesis, resulting in pale skin, light eyes, and blonde or red hair [1]. While light skin is evolutionary advantageous for vitamin D production in high-latitude regions, it provides very little natural protection against ultraviolet radiation [2]. As a result, individuals with this genotype have a significantly elevated risk of sun-induced skin damage [3]. This genotype is associated with an approximately 3-fold higher risk of cutaneous melanoma compared to carriers of the C allele [4]. It also increases the risk of basal cell carcinoma by over 1.5-fold and actinic keratosis by nearly 2-fold [5]. Additionally, the G/G genotype is linked to an increased susceptibility to rosacea, an inflammatory skin condition [6]. Regular sun protection is highly recommended for individuals with this genetic profile.
Significantly higher risk of melanoma, basal cell carcinoma, and actinic keratosis; Lighter skin pigmentation and higher sensitivity to sun exposure; Increased susceptibility to rosacea.
Variants with shared genetic architecture
rs28777 · SLC45A2 Gene · Chr 5 · Sleep Apnea Risk
rs12203592 · IRF4 Gene · Chr 6 · Skin Cancer Risk
rs6059655 · RALY Gene · Chr 20 · Skin Cancer Risk
Population differences of two coding SNPs in pigmentation-related genes SLC24A5 and SLC45A2.
Genome-wide study of hair colour in UK Biobank explains most of the SNP heritability.
Diversity and scale: Genetic architecture of 2068 traits in the VA Million Veteran Program.
Association of the SLC45A2 gene with physiological human hair colour variation.
SLC45A2: a novel malignant melanoma-associated gene.
Content updated August 2026.
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