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Gene Therapy Partially Restores Sight in Legally Blind Children

A promising study out of the United Kingdom has partially restored the vision of multiple small children born legally blind. The experimental treatment uses gene therapy to resolve a retinal disorder called LCA4, which prevents the eye from distinguishing objects in a person's environment. Though limited, the study suggests that blindness caused by genetic defects could be curable. LCA4—short for leber congenital amaurosis-4—is caused by a series of mutations in the AIPL1 gene, which is responsible for the function and survival of the retina's photoreceptors. When AIPL1 is defective, the eye can't see; at best, a person can only see vague spots of light. People with LCA4 experience blindness from infancy, with some losing even the ability to perceive light as they age. Today, it appears gene therapy can help to restore at least some LCA4-related vision loss. In a study at University College London's Institute of Ophthalmology, researchers placed healthy copies of the AIPL1 gene within a virus engineered to target retinal cells without triggering actual illness. (This part isn't particularly new; engineered adeno-associated viruses have been used to deliver DNA to cellular targets for years now.) Once in the retinal cells, the "new" AIPL1 gene replaced the defective version, helping to slow the deterioration of the retina and even develop healthy photoreceptors. The study was published in the February issue of The Lancet. In an effort to protect and build upon LCA4 patients' extremely limited sight before it was too late, the researchers selected children ages 1 through 3, who experienced severe retinal dystrophy but could still perceive small amounts of light. Each of four children received an injection of healthy AIPL1 in one eye while under anesthesia. Then the team monitored the children's health and vision, conducting different light and color perception tests as the children aged. A child participant locates a small white object against a dark background after receiving gene therapy for LCA4. Credit: Michaelides et al, The Lancet/DOI 10.1016/S0140-6736(24)02812-5 All four children showed "meaningful responses" to the therapy—in fact, while vision improved remarkably in every treated eye, each untreated eye lost its ability to perceive light entirely. The children gained the ability to sort different-colored crayons into cups, follow a pen light, locate tiny white objects on a dark background, navigate a normally lit corridor, identify doors, and even draw. According to the researchers, the children have each moved from "legally blind" status to "low vision" status, amounting to a massive quality-of-life upgrade. Since the completion of this study, the researchers have begun working with a second cohort of seven children who have received treatment in both eyes. Results of this trial aren't quite ready yet, but they must be encouraging, as the team notes they are "exploring the feasibility of making the [treatment] more widely available."