Heterochromia: Genetic condition that changes eye color

Have you met anyone with different colored eyes? Heterochromia, which affects six out of every 1, 000 people, is a genetic condition that causes the irises of the eyes to be various colors. This is caused by a lack or excess of melanin, the pigment responsible for giving color to our body, such as skin, hair and eyes. Rare in humans, the condition is most easily found in animals, especially domestic animals.

The difference in eye iris can be subtle, such as bows of different colors, or have a sharper contrast, such as one brown and one black eye. The cases are caused by variation in the EYCL3 and EYCL1 genes, both responsible for eye coloration. Those who have the condition do not have impaired vision and can live quietly with eyes of various shades.

Heterochromia in humans

Heterochromia in humans. (Source: Did You Know / Reproduction)

In the iris, there are three predominant pigments that determine the colors of the eye: brown, yellow and blue. Their mix results in the eye colors we are used to seeing. Those with heterochromia can mix these colors in one eye or have both eyes with each pigment. They are classified by different cases, but none are predisposed to disease or risk.

Sectoral heterochromia occurs when there are two colors in the same eye, with one as the dominant color. The difference is noted near the iris, and can affect one eye or both. The center, which is more common, indicates two or more circles of different colors, usually happening in one eye. Complete heterochromia is the rarest and occurs when both eyes have completely different colors.

In animals, it may indicate problems

Heterochromia in animals. (Source: Top Biology / Reproduction)

Unlike humans, complete heterochromia is more common in animals such as dogs of the Siberian husky breed. Although rare, different colors of pets' eyes may be related to changes in vision and some disabilities such as deafness.