A team led by University of Pennsylvania scientists has discovered three genetic variants that offer the first strong clues as to why glaucoma disproportionately affects Black people.

The variants are common in people with African ancestry and are associated with a significantly higher risk of developing the sight-robbing disease, the researchers found in their study of more than 11,000 volunteers, including 6,300 from the Philadelphia area.

More research is needed to determine if these variants — each consisting of just a single “letter” among the 3 billion pairs of letters that spell out the human genome — play a direct role in causing glaucoma. But if they stand up to scrutiny, the findings someday could be used to develop better treatments and identify people who could benefit from them, said Shefali Setia Verma, one of the lead study authors and an assistant professor at Penn’s Perelman School of Medicine.

“The idea is that this can help identify individuals who are at higher risk before any symptoms occur,” she said.

Previous studies have found more than 170 other genetic variants that are involved in glaucoma, a condition in which the optic nerve becomes damaged, often as a result of increased pressure inside the eye. But most of those studies were conducted among white or Asian populations — despite the fact that glaucoma is more common in Black people and, when it occurs, is more likely to lead to blindness.

And most of the genetic variants discovered in those previous studies turned out to play little or no role in the disease for Black people, illustrating the need for diversity in study populations, said Penn physician-scientist Joan M. O’Brien.

“It was a hugely unmet need,” she said.

Gaining trust from Black patients

That’s what prompted O’Brien, Verma, and their colleagues to launch the new study, which is among the first — and by far the largest — conducted among Black people.

O’Brien blamed the shortage of studies partly on the justifiable misgivings that many Black people hold about medical research, citing examples of misconduct such as the Tuskegee experiment in which Black men were not treated for syphilis.

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