Jun 6, 2016

Fighting Blindness Gets Sheepish

Eye On the Cure Research News

Researchers in Israel are developing a gene therapy for achromatopsia that may help both sheep and humans alike.

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Photo of a flock of sheep

We all know from the nursery rhyme "Mary Had a Little Lamb" that "everywhere that Mary went, the lamb was sure to go." But what if the lamb had a vision-robbing retinal disease, making it challenging to find Mary prancing around a sunlit meadow, or catching some rays on the Jersey Shore?

Well, in fact, there are sheep with a devastating inherited retinal disease known as achromatopsia, and they can't see in lighted conditions. Known as day blindness, the condition also affects more than 100,000 people worldwide.

But thanks to researchers in Israel developing a gene therapy, there's hope for both sheep and humans alike. The video below shows how gene therapy helped two sheep with achromatopsia navigate a maze to find their flock. Each of the sheep is shown unsuccessfully navigating the pen before treatment, and then finding his or her friends after receiving the therapy. (Make sure you turn up the audio for the complete viewing experience.)

The research team, led by Hadassah Medical Center's Eyal Banin, M.D., Ph.D., is working toward a trial of the gene therapy in humans. William Hauswirth, Ph.D., at the University of Florida, supplied the gene-delivery system — the human-engineered adeno-associated virus, or AAV — to deliver the healthy CNGA3 gene to the sheep retinas. Results of the team's sheep study were published in the journal Molecular Therapy.

Mutations in CNGA3 and CNGB3 cause approximately 75 percent of achromaotpisa cases. These defects affect cones, the retinal cells responsible for vision in bright settings, central and color vision and the ability to read and recognize faces.

Clinical researchers at University Hospital Tübingen in Germany recently launched a clinical trial of an achromatopsia gene therapy for people with CNGA3 mutations. Also, thanks, in part, to support from the Foundation Fighting Blindness, the gene-therapy development company Applied Genetic Technologies Corporation (AGTC) is launching a clinical trial of CNGB3 gene replacement therapy for achromatopsia. AGTC is also working toward a human study of a CNGA3 gene-therapy clinical trial.