ALBINISM AND LOW VISION: EXPLORING THE POSSIBILITIES OF GENE THERAPY
Leah Byrne
Albinism is in many ways a hidden condition, although roughly one in every 18,000 to 20,000 people in the United States live with some type of albinism, which can manifest in a range of conditions. While albinism affects people of all races and backgrounds, in sub-Saharan Africa the incidence of albinism has been estimated by researchers to be one in every 1,000 to 2,000 people.
The outward manifestations of albinism are obvious—lacking melanin, a person’s skin and hair appear white. But one consequence of living with albinism that is not commonly known is blindness. Or more commonly, vision low enough to qualify as legal blindness.
The little-studied aspects of albinism’s effects on vision drew scientist Leah Byrne into studying the genetic origins of the condition.
“We’re investigating which routes of administration and which gene therapies are the most efficient and beneficial.”
“People don’t often think of albinism as an eye disease or a disease affecting vision, but it’s actually one of the most challenging diseases,” explains Byrne, assistant professor of ophthalmology in the School of Medicine. “Patients suffer from severe photophobia—light sensitivity—and they also have poor visual acuity. I became interested in albinism because I think it’s an underserved disease and also an underserved area of research.”
Albinism is caused by mutations in a handful of genes that are important in the production of melanin, most commonly in the tyrosinase gene (OCA1).
Byrne’s team is exploring how those genetic mutations affect eyesight.
“Normally, a certain proportion of retinal ganglion cells cross over from one to the other hemisphere of the brain, but in albinism, the number of cells that cross is not the same. We think that is why patients with albinism have poor depth perception,” says Byrne. “Lack of pigment also results in severe photophobia. Those things can affect their quality of life.”
Gene therapy research for the condition is rare. Byrne’s lab specializes in developing nonpathogenic viruses that can efficiently deliver genes to the retina. “We think that perhaps we have a better and different approach for gene therapy for albinism,” Byrne says.
Graduate student Alessandra Larimer-Picciani leads the project in her lab. “We’re investigating which routes of administration and which gene therapies are the most efficient and beneficial,” she says.
The lab now works with animal models, but Byrne believes the research will lead to clinical applications in humans.
“We want to narrow down the gene therapies and try to understand how much benefit patients could expect to have if they were to receive the gene therapy in childhood or in adulthood,” says Byrne. “When would it make the most impact? What would the impact be?”