“You don’t know what you’ve got ‘til it’s gone.”
These words were made famous by singer Joni Mitchell and ring true of many circumstances in life. Perhaps nowhere more so than when we talk about our vision. In this case, I am referring to the rare eye disease known as choroideremia (CHM for short). At Penn Medicine we see many patients with rare and difficult-to-treat eye diseases, but CHM is getting a lot of attention around here these days.
Jean Bennett, MD, PhD, professor of Ophthalmology and director of the Center for Advanced Retinal and Ophthalmic Therapeutics (CAROT) at Penn Medicine, is a leader in using gene therapy for the treatment of rare eye diseases. What does this mean? She is essentially replacing a defective, disease-causing gene with a newer, working version of it. As Dr. Bennett said in a recent interview, “We’re basically taking advantage of viruses. What they do best is they deliver genes or nucleic acids to the target cells. But instead of using a virus which is found in the wild we’ve basically taken one which has never been shown to cause any disease and neutered it by removing its guts and replacing its guts with the gene of interest.”
So far, Bennett and her team have used gene therapy to treat a rare condition known as Leber’s Congenital Amaurosis or LCA. Patients with LCA are born severely visually impaired. They can sense light and see very large objects but with poor resolution and poor peripheral vision, all of which deteriorates with age. Bennett’s lab was able to deliver a normal copy of the gene which when mutated causes LCA to obtain amazing results. Many of the patients in the study showed improved vision and light sensitivity: a child who walked with a cane can now ride his bike and read; mothers could see their children clearly for the first time.Read more ...