Link Found Between African Descent and Genetic Variants in Glaucoma
A study recently conducted by the Penn Medical Center for Genetics of Complex Disease funded by the National Institutes of Health gained new insights from previously unknown inherited genetic variants that contribute to primary open-angle glaucoma (POAG). POGA is the most common form of the disease. The study was based on the analysis of 11,275 individuals of African descent. (1)
The research revealed that individuals of African ancestry are five times more likely to be affected by glaucoma and up to 15 times more likely to experience vision loss or blindness from the disease compared to individuals from European ancestry.
Reasons for Glaucoma
It is known that POAG can occur when the normal drainage of eye fluid becomes blocked, leading to a buildup of pressure within the eye. If the intraocular pressure rises too much, it can damage the optic nerve resulting in vision loss. Patients diagnosed with POAG can experience a loss of peripheral vision initially followed by loss in the central field of vision. Because there are no early warning signs of the disease, by the time the patient begins to experience vision loss, permanent damage has already occurred. According to Rebecca Salowe, MSE, Research Projected Manager and co-author, “Elevated intraocular pressure is currently the only targetable component of the disease, but many patients maintain normal pressure levels or do not responds to pressure-lowering therapies. This suggested to us that POAG has additional underlying mechanisms that could be elucidated by genetic studies.”
Actions Taken Because of the Findings
Using genome-wide association studies and other forms of genetic analysis, the researchers identified two gene variants implicated in the formation of glaucoma and subsequently found a third variant. In analyzing the findings, the researchers compared them with results primarily from people of European descent. They observed these variants were more common in people of African descent.
Based on these findings, researchers worked with community leaders in the African community to organize glaucoma screenings in churches and senior centers. They worked with a Black-owned radio station on a campaign promoting the importance of glaucoma screening in the community. There was no charge for the screenings and participants were provided with a free lunch regardless of whether they agreed to participate in the study.
Their focus is now on establishing better methods for diagnosing glaucoma early when there is better hope for treatment. Based on the identified key variants, researchers developed a polygenic risk score that exceeded a similar risk score designed using information from individuals of European ancestry. This improved risk score is expected to assist patients in making decisions about screening and treatment for glaucoma prior to it producing vision loss.
A concern is that current treatments for glaucoma are inadequate. According to Joan O’Brien, MD, the director of the Penn Medicine Center for Genetics of Complex Disease, “Precision medicine could be applied if we more clearly understood the full pathophysiology of this inherited neurodegeneration.” O’Brien noted they are sharing their genetic database with other researchers across departments and schools and are studying diseases that over-affect African ancestry populations.
- Cell, January 2024.
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