African Glaucoma Gene Clue

Three gene variants have been identified that may be contributing to the susceptibility of people of African ancestry to develop 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 most research has used data from people of European ancestry.

A study by researchers from Perelman School of Medicine at the University of Pennsylvania, published in Cell, 1 has identified two genetic variants correlated with primary open-angle glaucoma. These are “likely causal” of glaucoma, the study authors said.

A third variant was also identified. This was associated with cup-to-disc ratio, a measure of glaucoma severity.

The “mega-analysis” involved more than 11,200 people of African ancestry. According to a media release issued by Penn Medicine,2 only 2% of all genome-wide association studies have been conducted in individuals with ancestry tied to Africa.

Most previously associated genetic variants identified in other ancestral populations did not replicate in these African ancestry subjects.

“Our work is an important step toward defining subgroups of glaucoma, providing the capability for early screening, and discovering targetable pathways for personalised therapeutic interventions,” said study author Rebecca Salowe, from the Penn Center for Genetics of Complex Disease.

“This work highlights the essential role of diversity in genetic research,” first author Dr Shefali Setia Verma said. “Without our focus on this specific ancestry group, these unique and critical insights might have remained lost, and we would not have been able to substantially enhance our understanding of the genetics behind primary open-angle glaucoma in this overaffected population.”

A particular advantage that the researchers had in this study was the ability to validate their results in the Penn Medicine BioBank, an in-house repository of genetic information linked to health records. It features a particularly diverse collection of genetic material. Without that resource, it would have been “much more difficult to produce such strong work”, the authors said.

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.

“We are sharing our genetic database with other researchers… that are studying diseases that over-affect African-ancestry populations,” senior author Professor Joan O’Brien said. “These collaborations are resulting in much more research on the health of an historically understudied population.”

Prof O’Brien, a professor of Ophthalmology and director of the Penn Center for Genetics of Complex Disease, also explained her team is currently doing research to discover how exactly these genes contribute to glaucoma disease risk and severity.

With this new knowledge of the variants, the researchers hope to influence clinical approaches to glaucoma in this population and work toward reversing inequities that have persisted for many years.

References

1. Verma, S.S., Gudiseva, H.V., O’Brien, J.M. et al., (2024) A multi-cohort genome-wide association study in African ancestry individuals reveals risk loci for primary open-angle glaucoma, Cell 187(2), 464–480. DOI: doi.org/10.1016/j.cell.2023.12.006.   

2. Penn Medicine, Mega-analysis identifies gene variants associated with glaucoma in people of African ancestry (news release, 18 Jan 2024), available at: pennmedicine.org/news/news-releases/2024/january/gene-variants-tied-to-glaucoma-id-in-people-of-african-ancestry [accessed 19 Jan 2024].   

This article has been republished courtesy of Mivision.