Sight for sore eyes

(Edmonton) A medical research team at the University of Alberta has received $1.3 million to conduct a clinical trial of a gene therapy treatment for a rare eye disease that can leave men blind by their 30s.

Researchers hope the gene therapy will halt vision loss and possibly restore some vision for people living with the disease.

“People with choroideremia have been waiting their whole lives for news like this—that a possible treatment to stop vision loss and restore vision could be a reality,” says Ian MacDonald, chair of the U of A’s Department of Ophthalmology and an associate professor in the Department of Medical Genetics.

MacDonald is one of only a few choroideremia experts in the world. Some of his patients with choroideremia travel from other countries to seek his expertise and medical treatment. Edmonton was chosen as a site to host the trial because MacDonald and his expert team are based here.

Choroideremia is caused by an inherited gene mutation that affects the retina, causing the slow breakdown of vision cells. It affects males almost exclusively because the defect is found on the X chromosome, although women who carry one of the mutations have a 50 per cent risk of having an affected son, according to the Foundation for Fighting Blindness.

One of the first symptoms of choroideremia is night blindness. This is followed by a gradual loss of peripheral vision that will eventually result in complete blindness. It’s estimated that one out of every 50,000 Canadian males is affected.

Participants in the clinical trial, expected to start in late 2012, will undergo a surgical procedure in which a healthy gene is inserted underneath the retina, triggering the production of a protein that people with choroideremia don’t have.

MacDonald says the trial wouldn’t be possible without the five years of funding donated jointly by the Foundation Fighting Blindness, the Choroideremia Research Foundation Canada and the Canadian Institutes of Health Research.

The clinical trial will be the first in Canada to look at gene therapy for a retinal degenerative disease, says Sharon Colle, president and CEO of the FFB.

The first clinical trial of the same gene therapy started late last year in the U.K. Researchers in that trial, Robert MacLaren of Oxford University and Miguel Seabra of Imperial College London, will also collaborate on the Canadian project. Edmonton retinal surgeon and research team member Matt Tennant will travel to the U.K. to study the surgical technique and bring the expertise back to Edmonton.

The choroideremia trials build on technical advances developed in a U.S. gene therapy trial for another rare, genetic eye disease, Leber congenital amaurosis or LCA. The disease leaves children with such poor vision that they can barely navigate a small room.

Within weeks of receiving gene therapy treatment, children were able to see well enough to navigate the same room without any problems and could participate in normal childhood activities like playing catch. To see the difference in how a child could move around the same room before and after, watch these videos (there are two videos via the drop-down menu).