Gene Therapy May Avert Eye Disease Afflicting Boys

NEW YORK (Reuters Health) - A rare genetic eye disease that causes blindness in boys might be corrected by gene therapy in the not too distant future. This approach has restored vision in mice with the condition, called X-linked retinoschisis, researcher report.

The condition is caused by mutations in the gene encoding retinoschisin. Because the gene sits on the X chromosome, it only affects boys, who have only one X chromosome. The genetic defect results in degeneration of an area of the retina, the macula, which is essential for vision.

Delivering a normal retinoschisin (RS1) gene to mice with the genetic defect restores retinal integrity and function, Dr. Seok H. Min, at the University of Florida College of Medicine in Gainesville, and colleagues report in the research journal Molecular Therapy.

For their experiments, the researchers bred mice deficient in RS1. When the animals were 15 days of age, the team injected human RS1 attached to a viral carrier into the subretinal space of the right eyes; the left eyes were untreated in order to provide a comparison.

Six months later, deterioration of the inner retina seen in the left eyes was absent in the treated eyes. Measuring electrical signals from the rods and cones in the retina showed that visual function was significantly better in the treated eyes for at least 5 months.

In a press statement, co-author Dr. William W. Hauswirth, also at the University of Florida, comments, "It may take two to five years before we try this in human patients because of the need for safety studies, but we feel based on success so far, we will be able to provide formal evidence for safety that will allow us to get treatment into the clinic."

SOURCE: Molecular Therapy, August 2005.