12 Mar Many More Genes Discovered to Play a Role in Eye Color

MedicalResearch.com Interview with:

Dr Pirro Hysi
Senior Lecturer in Ophthalmology
Kings College London

MedicalResearch.com: What is the background for this study?

Response: – Iris (eye) color is an important human trait. It is one of the main features that makes our faces unique and recognizable. Iris color is similar to other pigmentatio traits, like hair and skin color, in that it is determined by the concentration and relative ratios of the melanin pigment. Pigmentation traits are roughly determined by several of the same genes regulating pigmentation, but many other genes seem to selectively determine pigmentation in any of these tissues.

MedicalResearch.com: What are the main findings?

Response: Our previous knowledge of eye colors was previously limited to about a dozen genes. Milder changes in their structure cause milder variations in eye color, but more severe disruptions caused albinism. While these genes have a strong influence over certain iris colors, they still explained only part of the variation we observe across populations. We are interested in finding out more about the genetics of eye color, because in addition to its purely esthetic implications, broadly speaking pigmentation and melanin metabolism are important in the context of certain diseases, such as skin cancer, certain forms of glaucoma (a potentially blinding disease), and also in extreme cases, for reasons that are still being investigated, the development of the optic nerve in the eye, which is responsible for taking the light signal all the way to the brain. 

MedicalResearch.com: What should readers take away from your report?

Response: In this study we report that hundreds of small changes in the human DNA can determine the iris color. None of them causes disruptions as severe as albinism, but they all participate to less dramatic changes in eye color.

The vast majority of the genes in which these changes are located are involved in melanin processing, which interesting as it allows us to have a better general understanding of how melanin metabolism is regulated. These genes are also prime candidates for diseases affected by disruptions in melanin regulation and production.

Although most of the eye color variation is observed among individuals of European ancestry (where the spectrum of eye color goes from light blue to very dark brown), many of the same genes also determine variations in other ethnic groups. While the variation in non-Europeans is less pronounced, the same genes caused milder but measurable changes in the eye colors.   

MedicalResearch.com: What recommendations do you have for future research as a result of this work? 

Response: Although it is certainly interesting for us to know for what reasons are eyes have a particular color, future research needs to focus on health implications of this study. Future directions include studying whether these genes have any systemic effect, whether they exert the same influence elsewhere and not just in the iris; whether the genes we just identified are just as capable of disrupting the disc of optic nerve in the eye, as the previously known genes.

Citation:

Genome-wide association study in almost 195,000 individuals identifies 50 previously unidentified genetic loci for eye color

 BY MARK SIMCOE, ANA VALDES, FAN LIU, NICHOLAS A. FURLOTTE, DAVID M. EVANS, GIBRAN HEMANI, SUSAN M. RING, GEORGE DAVEY SMITH, DAVID L. DUFFY, GU ZHU, SCOTT D. GORDON, SARAH E. MEDLAND, DRAGANA VUCKOVIC, GIORGIA GIROTTO, CINZIA SALA, EULALIA CATAMO, MARIA PINA CONCAS, MARCO BRUMAT, PAOLO GASPARINI, DANIELA TONIOLO, MASSIMILIANO COCCA, ANTONIETTA ROBINO, SEYHAN YAZAR, ALEX HEWITT, WENTING WU, PETER KRAFT, CHRISTOPHER J. HAMMOND, YUAN SHI, YAN CHEN, CHANGQING ZENG, CAROLINE C. W. KLAVER, ANDRE G. UITTERLINDEN, M. ARFAN IKRAM, MEREL A. HAMER, CORNELIA M. VAN DUIJN, TAMAR NIJSTEN, JIALI HAN, DAVID A. MACKEY, NICHOLAS G. MARTIN, CHING-YU CHENG, THE 23ANDME RESEARCH TEAM, THE INTERNATIONAL VISIBLE TRAIT GENETICS CONSORTIUM, DAVID A. HINDS, TIMOTHY D. SPECTOR, MANFRED KAYSER, PIRRO G. HYSI

SCIENCE ADVANCES10 MAR 2021 : EABD1239

A GWAS including 192,986 European and 1636 Asian participants identifies 50 novel discrete associations with eye color. 

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Last Updated on March 12, 2021 by Marie Benz MD FAAD