LONDON — Whether they’re green, or brown, or blue, what ends up deciding the color of someone’s eyes? Scientists have known that the amount of melanin in the iris tends to signal your eye color, however the genetic factors behind this process have been a little less clear. A new report now finds there are actually dozens of genes which play a role in controlling eye color. Researchers from King’s College London say the discovery may also help to better understand eye diseases in which the eye’s pigment is actually a factor.

An international team of scientists report that 50 previously unidentified genes help to determine human eye color. The study, involving nearly 195,000 people from Europe and Asia, is the largest genetic study on the subject to date.

Color coordination

Along with figuring out who will have what color eyes and why, the team notes that diseases like pigmentary glaucoma and ocular albinism also have a connection to eye color. Scientists previously suspected that only one or two genes were responsible for giving people bright blue or deep brown eyes.

The new research, however, builds on other studies which uncovered about dozen genes which play a role in eye color. Study authors also find Asians with different shades of brown eyes are genetically similar to Europeans who have a wider range from dark brown to light blue.

“The findings are exciting because they bring us to a step closer to understanding the genes that cause one of the most striking features of the human faces, which has mystified generations throughout our history. This will improve our understanding of many diseases that we know are associated with specific pigmentation levels,” say co-senior author Dr. Pirro Hysi in a university release.

“This study delivers the genetic knowledge needed to improve eye color prediction from DNA as already applied in anthropological and forensic studies, but with limited accuracy for the non-brown and non-blue eye colors,” concludes co-senior author Dr. Manfred Kayser from the Erasmus University Medical Center in the Netherlands.

The study appears in the journal Science Advances.

About Chris Melore

Chris Melore has been a writer, researcher, editor, and producer in the New York-area since 2006. He won a local Emmy award for his work in sports television in 2011.

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