Scientists have learned that human eye color genetics are far more complex than we knew. Reporting in Science Advances, an international team of researchers has identified over 50 new genes that contribute to eye color. These findings come after an analysis of genetic data from almost 200,000 European and Asian people.
The iris surrounds the black center of our eye called the pupil and is the part of our eyes that is pigmented. Iris colors are usually described as blue, brown, or grey/hazel. The most common eye color in the world is brown, and lighter eye colors tend to be found in individuals with European ancestry.
It was previously thought that only a few genes influenced the color of the iris and that genetically, brown colors would dominate blue ones. But eventually, a dozen eye color genes were discovered, and scientists suspected that there were more waiting to be found.
Now that researchers have revealed more, this work can not only tell us more about the biology underlying eye color, it can also provide new insights into diseases of the eye, like pigmentary glaucoma and ocular albinism; eye pigment levels are involved in both of those disorders.
"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," said co-senior study author Dr. Pirro Hysi of King's College London.
This study also found that the various shades of brown eye color found in Asian individuals have genetic similarities to Europeans with eye color ranges from light blue to dark brown; the genetics underlying eye color in both populations is similar.
"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," said co-senior study author Dr. Manfred Kayser of the Erasmus University Medical Center Rotterdam.