HERC2 rs11697325: Eye Color and Iris Pigmentation
The genetic variant rs11697325 is an intronic single nucleotide polymorphism located within the HERC2 gene on chromosome 15. It resides within a well-characterized genomic regulatory region known to modulate the expression of the nearby OCA2 pigmentation gene. Current research associates rs11697325 with subtle variations in human iris pigmentation and eye color, though its independent biological impact remains under active study.
What each genotype means
Typical OCA2 expression baseline
You carry two copies of the common C allele for rs11697325 in the HERC2 gene. This regulatory region influences OCA2 promoter activity, and the CC genotype is generally associated with standard baseline levels of melanin production in the iris. Your overall eye shade is determined primarily by primary determinant markers such as rs12913832 alongside broader polygenic factors.
Carried by approximately 60% to 65% of individuals of European ancestry and at higher frequencies in most non-European populations.
Modest regulatory pigmentation modifier
You carry one copy of the T allele and one copy of the C allele for rs11697325. Research suggests this intronic variation sits within a long-range enhancer locus that fine-tunes OCA2 expression, subtly modifying melanin density and pigment nuances. Its standalone effect is modest and serves as a secondary modifier rather than an absolute switch for blue or brown eye color.
Carried by roughly 30% to 35% of people of European ancestry, with lower frequencies observed in East Asian and African ancestries.
Altered enhancer activity nuance
You carry two copies of the minor T allele for rs11697325 in the HERC2 region. Scientific studies associate this genotype with subtle shifts in regulatory enhancer activity upstream of OCA2, contributing to slight variation in iris lightness or hue. Evidence indicates it functions as a fine-scale pigmentation modifier whose visible outcome remains dependent on your primary eye color loci.
Found in about 3% to 5% of individuals of European ancestry and is uncommon in other continental populations.
Genomic Location and Regulatory Context
The single nucleotide polymorphism rs11697325 is located within an intronic sequence of the HERC2 gene on the long arm of human chromosome 15 (15q13.1). Although the physical sequence change lies inside HERC2, genomic mapping and functional assays show that this chromosomal area harbors critical cis-regulatory elements. These non-coding sequences act as distant enhancers that loop across the genome to interact with the promoter of the adjacent OCA2 gene. Variants in this neighborhood can subtly modify how transcription factors bind to chromatin, thereby altering down-stream transcription rather than changing the amino acid sequence of any protein product directly.
Function of HERC2 and Cross-Talk with OCA2
The HERC2 gene encodes a large, multi-domain E3 ubiquitin-protein ligase that participates in cellular processes like DNA damage repair and intracellular trafficking. However, researchers have found that HERC2's primary ligase activity is largely unrelated to melanin synthesis. Instead, the locus is renowned in genetics because deep introns within HERC2 function as long-range regulatory switches for the neighboring OCA2 gene. OCA2 produces a crucial transmembrane P-protein involved in melanosomal pH regulation and the synthesis of eumelanin, which is the dark pigment responsible for brown eye, hair, and skin tones.
Scientific Evidence and Strength of Association
The evidence connecting rs11697325 to iris pigmentation is currently classified as limited. The overwhelming driver of blue versus brown eye color in this locus is the classic regulatory variant rs12913832, which directly affects long-range chromatin looping to the OCA2 promoter. Variants like rs11697325 reside on shared ancestral haplotypes in high linkage disequilibrium across the OCA2-HERC2 chromosomal segment. As a result, rs11697325 is statistically correlated with lighter eye shades, but scientific studies suggest it acts as a secondary modifier or linked marker rather than an isolated, primary causative driver of pigment phenotype.
Population Frequency and Diversity
Allele distributions for polymorphisms across the OCA2-HERC2 region vary substantially between global continental ancestries due to historical demographic expansion and positive natural selection in northern latitudes. The minor allele of rs11697325 is found primarily in individuals of European ancestry, carrying a minor allele frequency of approximately 0.20 according to reference data in the Genome Aggregation Database (gnomAD). In contrast, the variant is observed at dramatically lower frequencies or is entirely absent in most East Asian, African, and Indigenous American reference populations.
Interpreting Consumer Genetic Results
Learning your rs11697325 genotype provides an intriguing glimpse into human evolutionary genomics and complex polygenic traits, but it cannot definitively predict visible iris appearance. Eye color is an inherently multifactorial polygenic trait determined by epistatic interactions across several genes, including OCA2, HERC2, SLC24A4, TYR, and TYRP1. Furthermore, rs11697325 is a benign non-coding polymorphism that carries no diagnostic utility for ocular diseases or systemic health conditions, serving solely as an educational marker of physical trait genetics.
How common is this variant?
The minor allele of rs11697325 exhibits a minor allele frequency of approximately 0.20 in populations of European ancestry according to gnomAD datasets. It is rare or absent across most African, East Asian, and other non-European continental groups.
Frequently asked questions
Can rs11697325 tell me what eye color I have?
No, a single SNP cannot accurately dictate your eye color. Iris pigmentation is a complex trait governed by multiple interacting genes and major switch variants like rs12913832, meaning rs11697325 only offers subtle contextual information within a broader genetic profile.
Does having this variant cause eye disease or vision loss?
No, rs11697325 is not classified as a disease-causing pathogenic mutation in clinical databases. It is a benign intronic variant associated purely with natural normal-range human physical diversity.
Why is the variant in HERC2 if it affects OCA2?
The physical DNA of the human genome folds into three-dimensional loops. Regulatory enhancers located inside the introns of the HERC2 gene fold backward to physically interact with the promoter of the nearby OCA2 gene, directly influencing how much pigment protein OCA2 produces.
Is rs11697325 more important than rs12913832?
No. Extensive scientific functional research points to rs12913832 as the primary functional switch controlling human blue versus brown eye color, while rs11697325 is generally considered a secondary linked marker or nuanced modifier.
Sources & further reading
Educational information only, last refreshed 9/11/2026. 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.