A new analysis focusing specifically on people of African ancestry identified three gene variants that may be contributing to this population’s susceptibility to developing and being blinded by glaucoma.
People of African ancestry are five times as likely as others to develop glaucoma and up to 15 times as likely to be blinded by the condition, but the vast majority of research has used data from people of European ancestry. Led by researchers at the Perelman School of Medicine at the University of Pennsylvania, the study was published in Cell.
Involving more than 11,200 people of African ancestry, the new study uncovered two particular variants that correlated with primary open-angle glaucoma, the most common form of glaucoma, which is the leading cause of irreversible blindness worldwide. The variants discovered in the analysis were rs1666698, tied to the gene DBF4P2, and rs34957764, linked to ROCK1P1.
In addition to identifying these two variants as “likely causal” of glaucoma, a third variant was also identified (rs11824032 tied to ARHGEF12), which was associated with cup-to-disc ratio, a measure of glaucoma severity.
The majority of previously associated variants identified in other ancestral populations did not replicate in these African ancestry subjects, which could be tied to the genetic differences that occur in these different groups.
As of 2019, only two percent of all genome-wide association studies—analyses of entire genomes to find commonalities that correlate to disease or other traits—have been conducted in individuals whose ancestry is tied to Africa. The study, led by first author Shefali Setia Verma, PhD, an assistant professor in Pathology and Laboratory Medicine, Salowe, O’Brien, and Marylyn Ritchie, PhD, a professor of Genetics and director of the Institute of Biomedical Informatics, sought to work toward addressing that disparity while also looking into a condition that disproportionately affects individuals of African ancestry. It’s also an issue Penn Medicine has worked toward for decades, utilizing wide community-focused screenings that this new research could help to inform.
With the variants the researchers identified, a polygenic risk score—a measure of disease risk due to an individual’s genes—was developed that outperformed a similar risk score generated with information from an analysis of individuals of European ancestry. Having this improved risk score in hand could help patients make decisions about screening and treatment for glaucoma before it becomes a blinding illness.