Posted on Mar 18, 2021, 4 p.m.
The genetics of human eye colour is much more complex than previously thought, according to a new study published in Science Advances called “Genome-wide association study in almost 195,000 individuals identifies 50 previously unidentified genetic loci for eye color”.
An international team of researchers led by King’s and Erasmus University Medical Center Rotterdam have identified 50 new genes for eye colour in the largest genetic study of its kind to date. The study involved the genetic analysis of almost 195,000 people across Europe and Asia.
These findings will help to improve the understanding of eye diseases such as pigmentary glaucoma and ocular albinism, where eye pigment levels play a role.
In addition, the team found that eye colour in Asians with different shades of brown is genetically similar to eye colour in Europeans ranging from dark brown to light blue.
This study builds on previous research in which scientists had identified a dozen genes linked to eye colour, believing there to be many more. Previously, scientists thought that variation in eye colour was controlled by one or two genes only, with brown eyes dominant over blue eyes.
Co-senior author Dr. Pirro Hysi, King’s, said: “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.”
Co-senior author Dr. Manfred Kayser, Erasmus University Medical Center Rotterdam, said: “This study delivers the genetic knowledge needed to improve eye colour prediction from DNA as already applied in anthropological and forensic studies, but with limited accuracy for the non-brown and non-blue eye colours.”
“Human eye color is highly heritable, but its genetic architecture is not yet fully understood. We report the results of the largest genome-wide association study for eye color to date, involving up to 192,986 European participants from 10 populations. We identify 124 independent associations arising from 61 discrete genomic regions, including 50 previously unidentified. We find evidence for genes involved in melanin pigmentation, but we also find associations with genes involved in iris morphology and structure. Further analyses in 1636 Asian participants from two populations suggest that iris pigmentation variation in Asians is genetically similar to Europeans, albeit with smaller effect sizes. Our findings collectively explain 53.2% (95% confidence interval, 45.4 to 61.0%) of eye color variation using common single-nucleotide polymorphisms. Overall, our study outcomes demonstrate that the genetic complexity of human eye color considerably exceeds previous knowledge and expectations, highlighting eye color as a genetically highly complex human trait.”
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