Inherited Blindness Improved with Gene Therapy
There may now be hope for people with inherited blindness in the form of gene therapy. Researchers at the University of Pennsylvania School of Medicine and the University of Florida at Gainesville have reported their findings on inherited blindness in the August online edition of Human Gene Therapy and in a letter to the editor in the Aug. 13 issue of the New England Journal of Medicine.
The research involved three young adult patients in their early twenties with impaired vision due to the hereditary condition Leber Congenital Amaurosis (LCA). LCA caused mutations in the RPE65 gene which interferes with the proper working of light-sensitive photoreceptor cells in the retina.
In the phase I trial, researchers injected healthy copies of the RPE65 gene under the retina in the eyes of the participants. All three had been legally blind since birth. One year after treatment, the patients were able to detect very dim lights that they weren't able to see prior to treatment. The results provide evidence that the newly introduced RPE65 gene is functional and is increasing the light sensitivity of the retina.
Commenting on the one patient who is now able to read an illuminated clock for the first time, Samuel G. Jacobson, MD, PhD remarks “This fascinating finding shows that a person can adapt to the new vision resulting from gene therapy over a prolonged period of time. We will look closely at whether these slow visual gains could be accelerated with visual training in future studies.”
This Phase I clinical trial is supported by the National Eye Institute (NEI) at the National Institutes of Health. For additional information about LCA, visit www.nei.nih.gov/lca. Find more information about this trial (NCT 00481546) at www.clinicaltrials.gov.
Leber Congenital Amaurosis (LCA), a hereditary condition that causes severe vision impairment in infants and children. You can find more information at the Foundation Fighting Blindness.
Cideciyan AV, Hauswirth WW, Aleman TS, Kaushal S, Schwartz SB, Boye SL, Windsor EAM, Conlon TJ, Sumaroka A, Pang J, Roman AJ, Byrne BJ, Jacobson SG. (2009) Human RPE65 Gene Therapy for Leber Congenital Amaurosis: Persistence of Early Visual Improvements and Safety at 1 Year. Human Gene Therapy, vol. 20, no. 9; published online August 2009, ahead of print (doi: 10.1089/hum.2009.086).
Cideciyan AV, Hauswirth WW, Aleman TS, et al. Vision 1 Year after Gene Therapy for Leber's Congenital Amaurosis. N Engl J Med 2009; 361:725-727.