HERC2/OCA2: Eye Color

rs12913832 · Pigmentation & Traits

rs12913832 is the single strongest determinant of eye color in humans, explaining up to 74% of eye color variation in European populations.

What This SNP Does

This SNP sits in the HERC2 gene but acts as a regulatory switch for OCA2, the main gene controlling melanin production in the iris. The A allele reduces OCA2 expression, leading to less melanin and lighter eye colors. This single variant is so predictive that it's used in forensic DNA phenotyping to predict a person's likely eye color from crime scene DNA.

Genotype Meanings

Genotype	Status	What It Means
GG	Brown eyes likely	High OCA2 expression. Strong melanin production in iris. Brown eyes most probable (~85% in GG Europeans).
AG	Variable	Intermediate OCA2 expression. Green or hazel eyes common. Some brown or blue possible.
AA	Blue eyes likely	Reduced OCA2 expression. Blue or gray eyes most probable (~72% accuracy).

What You Can Do

Eye color is polygenic — other genes (SLC24A4, TYR, IRF4) modify the prediction. A full report uses multiple SNPs for more accurate eye color prediction using a multi-locus regression model.

This information is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider before making health decisions based on genetic data. Genome Decoder does not diagnose, treat, or prevent any disease.