The Genetic Architecture of Iris Colour and Surface Feature Variation in Populations of Diverse Ancestry

Research focused on iris colour and surface features has begun to play an increasingly important role in the fields of anthropology, forensics and public health. Although both eye colour and, to a much lesser extent, iris features have been studied in populations of European ancestry, very few research groups have attempted to investigate these traits in regions outside of Europe. This may be partly due to difficulties associated with obtaining a quantitative measurement of eye colour and a lack of standardized methodology. For my doctoral thesis, I developed a novel method of characterizing iris colour and feature variation in diverse populations. I then applied this method to a sample of individuals of East Asian, European and South Asian ancestry. I was primarily interested in looking at the phenotypic distribution and genetic basis of these traits across all three sample sets. I found that: 1/ Quantitative methods provide an ideal means of characterizing iris colour in populations of diverse ancestry; 2/ The phenotypic distributions of iris colour and surface features are different in East Asian, European and South Asian populations; 3/ HERC2 rs12913832 controls iris pigmentation variation in both European and South Asian populations. However, it affects eye colour differently in both regions; 4/ The variants responsible for controlling iris pigmentation in Europe are different from those responsible for controlling iris pigmentation in East Asia; 5/ SEMA3A rs10235789 is significantly associated with Fuchs' crypts in East Asian, European and South Asian populations. Ultimately, my thesis is the first research work to compare iris pigmentation and structure variation in populations of diverse ancestry. The methodology that I have developed will provide other researchers with a new framework that they can use to approach the study of iris colour and feature diversity.Ph.D