Visual Acuity after Retinal Gene Therapy for Choroideremia

In this study, the subfoveal injection of a gene-therapy vector carrying nonmutated CHM, the gene that, when mutated, causes a form of blindness called choroideremia, was followed by an improvement in visual acuity in two of six patients at 3.5 years after injection. To the Editor: Two recent clinical reports of retinal gene therapy with adeno-associated virus (AAV) vectors in patients with Leber’s congenital amaurosis showed initial gains in visual function that subsequently declined. 1 , 2 We previously reported early improvement in visual acuity in two of six patients who received retinal gene therapy in one eye (the study eye) to treat choroideremia, 3 a disease that is characterized by atrophy of the choriocapillaris and retinal pigment epithelium and involves vision loss that leads to blindness. Choroideremia is caused by loss-of-function mutations in the gene CHM . We delivered nonmutated CHM in an AAV vector . . .