New gene therapy for one of the most common types of congenital blindness has proven safe and effective in improving patients’ vision. The therapy delivers functional copies of GUCY2D to the eyes of patients with severe vision impairments caused by gene mutations.
Even with a low dose of gene therapy, the researchers observed long-term improvements in both day and night vision. The GUCY2D gene is one of approximately 25 human genes whose mutations cause retinal problems, resulting in severe vision impairment from birth or early childhood. This group of inherited retinal disorders, known as Leber Congenital Amaurosis (LCA), accounts for a significant portion of childhood blindness worldwide.
Even in adults with this condition for decades, many light-sensing retinal cells remain alive and intact despite their dysfunction. Adding functional copies of GUCY2D via gene therapy could thus reactivate those cells and restore some vision.
The first clinical trial of a GUCY2D gene therapy, a solution of a harmless virus that carries the gene and is injected beneath the retina — initially in only one eye per patient — began in 2019. Each patient is followed for two years after treatment.
The first patient noticed a significant increase in light sensitivity in rod cells, which are more sensitive than cone cells and are primarily responsible for low-light or “night vision.” This patient’s pupil responses to light were also improved.
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