Things to Know About Heterochromia

The majority of humans have two eyes that are the same color. It is possible, however, for some people to have eyes that are not the same color as each other. This condition is called heterochromia. It is also possible for certain types of animals to have different-colored eyes.

Those who are fans of the Washington Nationals baseball team might have noticed that pitcher Max Scherzer has one blue eye and one brown eye. The Washington Post reported that Max Scherzer has heterochromia iridum. This genetic anomaly affects roughly 1 in 500 people.

The Washington Post article includes some comments from Max’s mother Jan Scherzer. She said she noticed that Max had one blue eye and one green eye when he was 4 months old. She took him to a doctor, who said that Max’s eyes could change again within the year. The doctor was right; the blue eye got bluer and the green eye changed to brown.

Heterochromia means “different (hetero-) colors (-chromia).” Heterochromia is not an eye disease, and it does not affect a person’s vision. People who have heterochromia are either born with it, or they develop it in early childhood as the iris attains its full amount of melanin.

Congenital heterochromia is caused by a genetic trait that is inherited. It can occur as the result of a genetic mutation during embryonic development. Scientific American reported that the color of a person’s eyes is a manifestation of the pigment that is present in the iris. Brown eyes have rich melanin deposits; blue eyes indicate a lack of melanin.

The same Scientific American article notes that two genes control eye color. One is EYCL3, which is found on chromosome 15. It codes for brown/blue eye color. The other is EYCL1, which is found on chromosome 19. It is believed to code for green/blue eye color. How these genes interact to produce eye colors such as hazel or grey is unknown.

There are different types of heterochromia. An individual who has two different-colored eyes has heterochromia iridium. A person who has a variety of colors within a single iris has heterochromia iridis. These conditions do not cause harm to a person’s vision.

A person who has a sudden onset of heterochromia should see a doctor. There are several inherited diseases that include sudden heterochromia as a symptom. A change in eye color can also result from an eye injury.

Related Articles at

* Your Ancestor had Different Colored Eyes?

* Enchroma Helps Color Blind People to See Colors

* How Much Do You Know About Your Genes?

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