HERC2 rs2327089: Genetics of Human Eye Pigmentation
rs2327089 is an intronic single nucleotide polymorphism located within the HERC2 gene on chromosome 15. Research in forensic DNA phenotyping has identified this variant as part of broader haplotype patterns associated with normal human eye pigmentation differences. It acts as a secondary genetic marker alongside primary regulatory switches in the OCA2-HERC2 genomic locus.
What each genotype means
Associated with non-blue eyes
This genotype is associated with a higher likelihood of having brown or non-blue eye pigmentation. Research indicates that this variant in the HERC2 gene region influences the expression of the neighboring OCA2 gene, which is critical for melanin production in the iris.
This genotype is common in populations with higher frequencies of brown eye color, though exact frequencies vary significantly by ancestry.
Intermediate pigmentation association
Carrying one copy of each allele suggests an intermediate genetic influence on eye pigmentation. While this variant is a known marker for eye color, individual phenotype is determined by the complex interaction of multiple genetic factors and environmental influences.
This heterozygous genotype is observed in diverse populations, particularly those with mixed ancestral backgrounds.
Associated with blue eyes
This genotype is statistically associated with a higher probability of having blue eye color. It is part of a genetic signature in the HERC2-OCA2 region that is frequently used in forensic DNA phenotyping to predict eye color in individuals of European descent.
Carried by a significant portion of individuals of European ancestry, where blue eye color is most prevalent.
Genomic Location and Variant Characteristics
The single nucleotide polymorphism rs2327089 resides within an intronic region of the HERC2 gene on chromosome 15 (15q13.1). Because it falls inside a non-coding intron rather than an exon, it does not alter the amino acid sequence of the resulting protein. Instead, variants in this genomic region are primarily investigated for their roles in gene regulation or as informative linkage disequilibrium markers. The primary alleles evaluated at this locus are thymine (T) and cytosine (C). In genomic reference catalogs, this locus is cataloged as a neutral, non-pathogenic sequence variation common in human populations.
The Biological Role of HERC2 and Pigmentation Regulation
The HERC2 gene encodes a large, multifunctional E3 ubiquitin-protein ligase involved in cellular DNA repair pathways and protein degradation. However, its most widely recognized role in human genetics involves pigmentation. A key regulatory element located inside intron 86 of HERC2 acts as a long-range enhancer controlling the promoter of the neighboring OCA2 gene. The OCA2 protein is essential for the maturation and proper transport of melanin within melanosomes. Alterations in the HERC2-OCA2 genomic neighborhood modify OCA2 transcription, shifting the cellular production of eumelanin and resulting in visible differences in human eye, skin, and hair color.
Association With Eye Color and Scientific Evidence
Evidence linking rs2327089 to eye pigmentation is classified as moderate. While primary pigmentation panels like IrisPlex rely heavily on the well-known functional variant rs12913832, extended forensic phenotyping studies and association analyses examine additional intronic markers such as rs2327089. These studies show that rs2327089 exhibits moderate statistical associations with subtle iris pigmentation gradients. Because human eye color is a polygenic trait characterized by complex linkage disequilibrium blocks across the OCA2-HERC2 region, rs2327089 frequently tracks alongside other non-coding variants rather than acting as a standalone causal driver of phenotype.
Population Frequency and Ancestral Distribution
Allele distributions for rs2327089 vary across global ancestries, reflecting the demographic and evolutionary history of pigmentation traits. In reference databases including gnomAD, the minor C allele occurs at a frequency of approximately 0.14 (14%) in European populations, making the T allele the dominant form across broad cohorts. In many non-European ancestral groups, the genomic region shows significantly less diversity, with high fixation of ancestral alleles. These frequency skews illustrate how natural selection and geographic isolation shaped the architecture of human physical traits.
Practical Implications for Consumers and Researchers
Genotype information for rs2327089 provides intriguing anthropological and educational insight into the genetics of appearance, but it cannot be used in isolation to diagnose any health condition or reliably determine an individual's eye color. Eye color is shaped by coordinated contributions across multiple loci, most notably OCA2, SLC24A5, SLC45A2, and TYR. Knowing one's genotype at rs2327089 reflects only a small piece of this polygenic architecture. Furthermore, this variant is purely associated with normal cosmetic diversity and carries no clinical or diagnostic significance.
How common is this variant?
The C allele has a frequency of approximately 0.14 in European populations according to gnomAD, while the T allele remains the predominant ancestral allele globally.
Frequently asked questions
Does the rs2327089 variant determine my exact eye color?
No, rs2327089 does not determine your eye color on its own. Human eye color is a polygenic trait influenced by several genes, predominantly driven by the nearby HERC2 regulatory variant rs12913832 and OCA2 expression.
Is the HERC2 rs2327089 variant associated with any medical diseases?
No, rs2327089 is considered a benign, neutral variant associated with normal physical traits. It is not classified as pathogenic in clinical databases like ClinVar and does not cause ocular diseases.
Why is rs2327089 included in forensic DNA phenotyping panels?
Forensic phenotyping panels examine combinations of SNPs across the genome to statistically reconstruct physical appearance from biological samples. Markers like rs2327089 help refine predictions for intermediate shades of eye color by capturing regional haplotype structure.
How does HERC2 influence eye color if it is not a pigment gene?
HERC2 contains an enhancer sequence inside one of its introns that loops over to activate the transcription of the adjacent OCA2 gene. OCA2 produces a critical transporter required for melanin production in the iris.
Sources & further reading
Educational information only, last refreshed 9/8/2026. 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.