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Researchers at the Penn Medicine identified gene variants associated with glaucoma in people of African descent.

Credit: Anna Vazhaeparambil

A recent study published by Penn’s Center for Genetics of Complex Disease revealed new genetic risk factors of glaucoma for people of African ancestry.

The Penn researchers identified three new gene variants that may contribute to glaucoma in people of African ancestry and developed a polygenic risk score to measure disease risk based on an individual's genes. The genome-wide analysis, published on Jan. 18, was the largest-ever study analyzing genetic risks for glaucoma of African ancestry.

The study enrolled 6,000 participants of African ancestry, as that population is disproportionately affected by glaucoma. Researchers performed a mega-analysis including other genetically similar datasets, reaching a total of 11,275 participants.

Primary open-angle glaucoma, a subset of glaucoma, affects 44 million people globally and is projected to nearly double by 2040. 

POAG is a condition that occurs when eye fluid does not drain properly, leading to dangerous pressure buildup. Penn researchers identified 46 risk loci — specific locations on the human genome — associated with the disease.

Upon further analysis, researchers characterized three genetic variants — two of which were previously unknown — as “likely causal” of primary open-angle glaucoma. The effects of these variants were less pronounced in groups without African ancestry.

The new genetic database will be “shared with other researchers across departments and schools that are studying diseases that over-affect African-ancestry populations,” Principal Investigator of the Penn Center for Genetics of Complex Disease Joan O’Brien wrote to The Daily Pennsylvanian.

People of African ancestry are five times likelier than people of European ancestry to experience glaucoma and 15 times more likely to experience vision loss or blindness. However, the population of individuals of African ancestry remains largely understudied regarding both glaucoma and genetic research overall.

“Only 2% of total participants in genome-wide association studies were of African descent [as of 2019]," study author and Research Project Manager Rebecca Salowe wrote to the DP. "This disparity not only limits understanding of disease biology but also impedes the translation of findings into clinical action for the most affected group.”

According to Salowe, when genetic screening guidelines and polygenic risk scores are developed based on research of a genetically homogenous population, this can result in inaccurate results and diagnoses for the broader, genetically diverse population.

"This further exacerbates and perpetuates long-standing health disparities," Salowe wrote. "Our long-term goal is to translate this information into more personalized and targeted diagnostic and therapeutic strategies for this over-affected and understudied population."

While current treatments include lowering intraocular pressure through medications, surgery, and laser treatment, O'Brien told the DP that the damage caused by the disease is irreversible. This blindness “perpetuates increased morbidity, poverty, and mortality across generations,” O’Brien wrote. 

The researchers said that they took extra steps to both incentivize the participation of people of African ancestry in the study and protect their interests.

“We sought to employ a framework of cultural humility that was sensitive to the needs of Black people, prioritizing patient comfort and access to glaucoma specialists,” O’Brien wrote.

The researchers partnered with Black community leaders, offered financial assistance for the transportation of participants, presented various insurance options, and ensured African-American presence on the team, according to O'Brien.

The research team hosted complimentary glaucoma screenings at churches and senior centers during weekends for those without access to care. They also collaborated with WURD Radio — a Black-owned Philadelphia radio station — to emphasize to the Black community the importance of glaucoma screening.