The Genetic Switch Behind Eye Color - rs12913832

The rs12913832 eye color variant is one of the strongest and most well-studied genetic markers influencing human eye color. Located within the HERC2 gene, this SNP acts as a regulatory switch that controls the activity of the nearby OCA2 gene, which plays a central role in pigmentation [R, R].

You can analyze how rs12913832 appears in your DNA at GenesUnveiled.

How rs12913832 Influences Eye Color

Rather than changing a pigment directly, rs12913832 influences eye color by regulating gene expression [R, R]:

• The variant sits in a regulatory region of HERC2

• This region controls how strongly OCA2 is expressed in iris cells

• OCA2 activity determines how much melanin is produced in the eye

• Lower melanin leads to lighter eye colors; higher melanin leads to darker eyes

This makes rs12913832 a classic example of a gene regulatory variant with a visible physical effect.

Eye Color as a Polygenic Trait

While rs12913832 has a major influence, eye color is not determined by a single SNP alone. Other genes—including OCA2, TYR, SLC24A4, and IRF4—also contribute to pigmentation differences.

Together, these genes shape a spectrum of eye colors rather than discrete categories, explaining why intermediate shades such as green or hazel exist.

Why rs12913832 Is Scientifically Important

The rs12913832 eye color variant is widely used in:

• Human genetics research

• Population genetics and ancestry inference

• Forensic DNA phenotyping

• Studies of gene regulation and expression

It is often cited as one of the clearest examples of how non-coding DNA can have a powerful biological effect.

Explore Your Trait Genetics

Eye color is one of many visible traits influenced by genetics. Variants like rs12913832 highlight how small regulatory changes can lead to noticeable differences in appearance.

You can analyze your broader trait and pigmentation genetics at GenesUnveiled.