What you carry at this position in your DNA and what research says about it.
Skin Cancer and Cataract Risk: 10/10 evidence, 38 publications.
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Sample genotype (not yours): C/C
Lower Risk of Skin Cancer and Cataracts
Lacking the T variant keeps the risk of skin cancers and cataracts at baseline. Lighter eye colors like blue or gray are also more common with this genetic profile.
What this genotype means: Typical risk of skin cancers; Typical risk of cataracts; Higher likelihood of blue or gray eyes.
Sample genotype (not yours): C/T
Slightly Higher Skin Cancer and Cataract Risk
Carrying one copy of the T variant is linked to a slightly increased risk of skin cancers and cataracts. This genetic change is also associated with green, hazel, or darker eye colors.
What this genotype means: Slightly increased risk of skin cancers; Slightly increased risk of cataracts; Higher likelihood of green or hazel eyes.
Sample genotype (not yours): T/T
Higher Skin Cancer and Cataract Risk
Carrying two copies of the T variant is associated with an elevated risk of skin cancers and cataracts. Lighter skin, increased sun sensitivity, and green or hazel eyes are common with this profile.
What this genotype means: Increased risk of skin cancers; Increased risk of cataracts; Higher likelihood of green or hazel eyes.
Gene function and biological role
Gene Function: The OCA2 gene encodes the melanosomal transmembrane protein, which is crucial for the production of melanin [1]. Melanin is the primary pigment responsible for coloring our skin, hair, and eyes [1]. This protein plays a key role in regulating the pH and maturation of melanosomes, the cellular compartments where pigment is synthesized [2]. Variations in this gene can lead to differences in normal pigmentation or cause oculocutaneous albinism [1].
Variant Impact: The rs1800407 variant is a missense mutation in the OCA2 gene, changing the amino acid arginine to glutamine at position 419 [1]. This specific alteration results in a hypomorphic protein with reduced functional capacity [2]. The decreased activity of the protein leads to lighter pigmentation phenotypes and increased sensitivity to ultraviolet radiation [2]. It represents one of the most well-studied genetic markers for eye color variation in European populations [1].
Key Insight: This variant is one of the top genetic predictors of eye color, specifically linked to green or hazel eyes. The same genetic change that influences eye color also slightly increases the risk of developing cataracts and skin cancers.
Location: OCA2. Chromosome 15 · 15q13.1 · 28.0 Mb
Origin Story: The derived T allele is thought to have undergone positive selection in European populations, potentially co-evolving with other regulatory variants to favor lighter eye and skin pigmentation in high-latitude environments.
Estimated prevalence by population
Global 90.6%; European 86.3%; African 97.2%; East Asian 99.8%; South Asian 93.8%; Americas 87.0%; Ashkenazi 90.4%; Finnish 91.6%; Middle Eastern 94.6%; Amish 85.6%.
Estimated CC genotype frequency.
Global 9.1%; European 13.2%; African 2.8%; East Asian 0.2%; South Asian 6.1%; Americas 12.5%; Ashkenazi 9.4%; Finnish 8.2%; Middle Eastern 5.3%; Amish 13.8%.
Estimated CT genotype frequency.
Global 0.3%; European 0.5%; African < 0.1%; East Asian < 0.1%; South Asian 0.1%; Americas 0.4%; Ashkenazi 0.2%; Finnish 0.2%; Middle Eastern 0.1%; Amish 0.6%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cancer & Oncology
Skin Cancer
Skin Cancer. Evidence: 9/10. Source: PMID 15889046. Typical Risk.
Organ Systems
Vision & Eye Health
Cataract. Evidence: 10/10. Source: PMID 34127677. Typical Risk.
Pigmentation & Appearance
Eye Color. Evidence: 10/10. Source: PMID 12163334. Blue or Gray Eyes.
Sun Sensitivity. Evidence: 8/10. Source: PMID 29739929. Typical Sensitivity.
Showing effects for C/T genotype
Skin Cancer. Evidence: 9/10. Source: PMID 15889046. Slightly Higher Risk.
Cataract. Evidence: 10/10. Source: PMID 34127677. Slightly Higher Risk.
Eye Color. Evidence: 10/10. Source: PMID 12163334. Green or Hazel Eyes.
Sun Sensitivity. Evidence: 8/10. Source: PMID 29739929. Slightly Higher.
Showing effects for T/T genotype
Skin Cancer. Evidence: 9/10. Source: PMID 15889046. Higher Risk.
Cataract. Evidence: 10/10. Source: PMID 34127677. Higher Risk.
Sun Sensitivity. Evidence: 8/10. Source: PMID 29739929. Higher Sensitivity.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Melanin production remains fully functional with two copies of the common C allele [1]. This optimal pigmentation provides standard protection against ultraviolet radiation, maintaining a baseline risk for skin cancers such as melanoma and squamous cell carcinoma [1]. Additionally, the risk of developing age-related cataracts remains at the typical population level [2]. Eye color is more likely to be blue or gray in individuals with this genotype, depending on other regulatory genes [3]. Standard sun protection measures, such as wearing sunscreen and sunglasses, are still recommended to maintain long-term skin and eye health. Regular dermatological screenings can help monitor skin changes over time. Maintaining a healthy diet rich in antioxidants also supports overall ocular health.
Typical risk of skin cancers; Typical risk of cataracts; Higher likelihood of blue or gray eyes.
Sample genotype: CT (Heterozygous)
A single copy of the T allele produces a hypomorphic version of the OCA2 protein with reduced activity [1]. This reduction in protein function leads to lighter skin pigmentation and a decreased tanning response, making the skin more sensitive to sun exposure [2]. Consequently, the risk of developing cutaneous melanoma and squamous cell carcinoma is slightly elevated [1]. The risk of age-related cataracts is also marginally increased [3]. Green, hazel, or brown eyes are more frequently observed in individuals carrying this variant [4]. Utilizing broad-spectrum sunscreen and wearing UV-blocking sunglasses are practical ways to mitigate these elevated risks. Regular skin checks by a dermatologist are highly beneficial for early detection of any unusual moles or lesions.
Slightly increased risk of skin cancers; Slightly increased risk of cataracts; Higher likelihood of green or hazel eyes.
Sample genotype: TT (Homozygous)
Two copies of the T allele significantly reduce the activity of the OCA2 protein, which is essential for normal melanin synthesis [1]. This functional deficit results in lighter skin pigmentation and a highly sensitive tanning response [2]. The risk of developing cutaneous melanoma and squamous cell carcinoma is notably increased compared to the general population [1]. There is also a higher likelihood of developing age-related cataracts [3]. Green or hazel eyes are highly characteristic of this genotype when combined with other European pigmentation markers [4]. Consistent use of high-SPF sunscreen, protective clothing, and UV-filtering eyewear is highly recommended to protect both skin and vision. Scheduling annual skin examinations with a healthcare professional can aid in early detection and prevention.
Increased risk of skin cancers; Increased risk of cataracts; Higher likelihood of green or hazel eyes.
Variants with shared genetic architecture
rs121918166 · OCA2 Gene · Chr 15 · Albinism and Pigmentation
rs1800404 · OCA2 Gene · Chr 15 · Skin and Eye Color
rs1800414 · OCA2 Gene · Chr 15 · Skin Pigmentation
P gene as an inherited biomarker of human eye color.
Content updated August 2026.
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