HERC2 rs1667398: What Your Genotype Means
The rs1667398 variant is a single nucleotide polymorphism located within the HERC2 gene. It is recognized for its association with variations in human iris and hair pigmentation, primarily in individuals of European ancestry.
What each genotype means
Typical darker pigmentation tendency
You carry two copies of the common ancestral C allele at rs1667398. In published association studies, this genotype is typically correlated with darker iris color (such as brown or hazel) and darker hair tones, largely through linkage with key OCA2 regulatory elements. However, eye and hair color are complex polygenic traits influenced by multiple independent variants across several pigmentation loci.
Carried by approximately 60% to 70% of people of European ancestry and nearly 100% of individuals of East Asian and African ancestries.
Intermediate pigmentation tendency
You carry one copy of the T allele associated with lighter pigmentation at rs1667398. Because this regulatory region works alongside broader HERC2/OCA2 haplotypes, having one T allele is modestly associated with an increased likelihood of lighter eye and hair colors compared to the CC genotype. The ultimate expression of your eye and hair color depends on your genotypes across other major pigmentation genes such as SLC24A4 and IRF4.
Found in about 25% to 35% of individuals of European descent and is very rare or absent in African and East Asian populations.
Lighter pigmentation tendency
You carry two copies of the minor T allele at rs1667398. Research shows that homozygous carriers of this allele have a significantly higher statistical likelihood of lighter iris pigmentation (such as blue or green eyes) and lighter hair shades in European cohorts. This SNP functions as a trait marker rather than a clinical risk factor, and eye color is ultimately determined by an interplay of multiple genetic loci.
Present in roughly 2% to 6% of European populations, but extremely rare or unobserved in East Asian and African ancestries.
Understanding the SNP and Its Location
The variant rs1667398 is a single nucleotide polymorphism (SNP) situated on chromosome 15 within the HERC2 gene. This specific genomic region is highly significant in human genetics because it sits in close proximity to the OCA2 gene. The HERC2/OCA2 locus is widely studied due to its profound influence on the production of melanin, the pigment responsible for the color of our eyes, hair, and skin. Because this SNP is located in a regulatory region, it is thought to influence how nearby genes are expressed rather than altering the structure of a protein directly. Researchers often use this locus as a primary focus when investigating the genetic architecture of pigmentation traits, as it serves as a key marker for understanding the biological pathways that lead to the diverse range of eye and hair colors observed globally.
The Role of the HERC2 Gene
The HERC2 gene provides instructions for making a protein that acts as a ubiquitin ligase, which helps tag other proteins for degradation within the cell. While its primary function involves protein regulation, its location adjacent to the OCA2 gene is what makes it a focal point for pigmentation research. The OCA2 gene is essential for the maturation of melanosomes, the structures in cells that produce and store melanin. Research suggests that variants within the HERC2 gene, including those in the regulatory sequences near OCA2, can modulate the expression of the OCA2 protein. By influencing the amount of OCA2 produced, these genetic variations indirectly dictate the amount of melanin deposited in the iris and hair follicles. This regulatory relationship is a classic example of how non-coding genetic variants can have significant phenotypic effects by controlling the activity of neighboring genes.
Research Associations and Evidence Strength
Scientific literature, including numerous genome-wide association studies (GWAS), has consistently identified the HERC2/OCA2 locus as a major determinant of human eye color. While rs1667398 is one of several SNPs in this region linked to pigmentation, the evidence for its specific individual effect is considered limited compared to other lead SNPs in the same region, such as rs12913832. Most studies emphasize that pigmentation is a polygenic trait, meaning it is influenced by the cumulative effect of many variants across the genome, including those in genes like SLC45A2, SLC24A4, and IRF4. While the association between the HERC2/OCA2 region and eye color is robust and reproducible, the specific contribution of rs1667398 is often analyzed as part of a broader haplotype or linkage disequilibrium block. Consequently, while the association is statistically significant in large cohorts, it should be viewed as one piece of a complex, multi-gene puzzle rather than a sole predictor of physical traits.
Population Frequency and Distribution
The distribution of the rs1667398 variant varies significantly across different global populations. In European populations, the minor allele frequency typically ranges between 0.15 and 0.25. This frequency reflects the historical selection pressures and population movements that have shaped the genetic landscape of Europe. Conversely, this variant is observed to be rare or absent in many East Asian and African ancestral groups. This clinal distribution—where allele frequencies change gradually across geographic space—is a common feature of pigmentation-related variants. Because the variant is most prevalent in populations where eye and hair color diversity is high, it is frequently used in studies focusing on European genetic architecture. Understanding these frequency differences is crucial for researchers to avoid bias and ensure that genetic findings are interpreted within the appropriate ancestral context.
Interpreting Your Genetic Information
Information regarding your genotype at rs1667398 provides insight into the genetic factors that may contribute to your physical traits, such as eye or hair color. However, it is important to recognize that genetics is not destiny; physical appearance is the result of a complex interaction between your DNA and environmental factors. You cannot use this information to diagnose health conditions or predict complex traits with absolute certainty. If you are curious about your genetic makeup, view these results as educational data points rather than medical or definitive biological conclusions. Always approach direct-to-consumer genetic reports with a critical eye, and remember that professional genetic counseling is the best way to understand the implications of your specific genetic profile. This variant is not associated with medication response, but if you have concerns about any health-related genetic findings, you should always discuss them with a qualified healthcare provider or a genetic counselor.
How common is this variant?
The minor allele frequency for rs1667398 is approximately 0.15-0.25 in European populations, while it remains rare in East Asian and African ancestries.
Frequently asked questions
Does rs1667398 determine my eye color?
While rs1667398 is located in a region strongly associated with eye color, it is only one of many genetic factors involved. Pigmentation is a complex, polygenic trait, and no single SNP can definitively predict your eye color.
Is this variant linked to any health conditions?
The rs1667398 variant is primarily studied for its role in pigmentation traits. There is no current evidence suggesting it is a marker for disease or clinical health conditions.
Why is this variant common in Europeans but rare elsewhere?
Genetic variants related to pigmentation often show clinal distribution due to historical evolutionary pressures and migration patterns. The frequency of this variant reflects the specific genetic history of European populations.
Can I use this information to predict my children's eye color?
Predicting eye color based on a single SNP is not scientifically accurate. Eye color inheritance involves multiple genes and complex interactions that cannot be determined by looking at one variant alone.
Sources & further reading
Educational information only, last refreshed 10/19/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This variant is located in an intron of HERC2 and acts as a major regulatory marker for OCA2 expression, strongly influencing human eye color variation.
A well-documented marker in the HERC2/OCA2 region strongly associated with blue vs. brown eye color variation.
Intronic regulatory modifier in HERC2 acting as an enhancer upstream of OCA2 to fine-tune human iris pigmentation and hair shade traits.
A non-coding variant in the HERC2 regulatory region that modulates OCA2 expression and eye color.
Variant in the HERC2-OCA2 regulatory locus significantly associated with iris pigmentation and blue versus non-blue eye color variation.
Strongly determines human eye color; the C allele is associated with blue eye color and the T allele with brown eye color via long-range regulation of the OCA2 promoter.