GWAS of cataract in Puerto Ricans identifies a novel large-effect variant in ITGA6

Cataract is a common cause of vision loss and affects millions of people worldwide. Genome-wide association studies (GWAS) and family studies of cataract have demonstrated a role for genetics in cataract susceptibility. However, most of these studies have been conducted in populations of European or Asian descent, leaving the genetic etiology of cataract among Hispanic/Latino (HL) populations unclear. Here we perform the first GWAS of cataract in a Puerto Rican population of research participants derived from the customer base of 23andMe, Inc. In our analysis with 3,060 self-reported cases and 41,890 controls, we found a novel association of large effect size with a rare coding variant in the ITGA6 gene (rs200560853, p-value=2.9x10-12, OR=12.7, 95% CI=[6.5, 24.7]). ITGA6 is part of the integrin alpha chain in the laminin receptor subfamily, and likely contributes to eye lens homeostasis, transparency, and cell survival. We found that this coding variant is associated with a 13.7 year earlier disease onset on average, as well as a 4.3-fold higher rate of cataract events in the Puerto Rican population. The variant has a minor allele frequency (MAF) of 0.089% in Puerto Rico and is extremely rare elsewhere in the world. Population genetic analyses showed that the variant is only found in individuals with ancestry from the Americas and countries bordering the Mediterranean Sea, suggesting a North African origin. Our discovery identifies a novel genetic risk factor for cataract in Puerto Ricans and highlights the importance of including underrepresented populations in genomics research to improve our understanding of disease in all populations.