Four patients affected by Leber congenital amaurosis (LCA) have reported an improvement in their sight after under going gene therapy.
LCA usually begins affecting sight in early childhood and by the time the sufferer is 30 they are totally blind. Until now, there was no treatment.
A common cold virus was used to deliver a normal version of the damaged, disease causing, gene directly into the eyes of volunteers. These first tests were merely safety markers and yet volunteers reported they could see better afterwards. In one test, all three volunteers responded positively and in another, one out three volunteers improved. The volunteers were all adults suffering severe sight loss and, as it was a benchmark test, received the therapy in very low doses. The researchers
had not expected to see any benefit at all.
Before the test, Steven Howarth struggled to see in dim light. “Now my sight, when it’s getting dark or it’s badly lit, is defi nitely better. It’s a small change - but it makes a big difference to me,” said Howarth.
“Patients’ vision improved from detecting hand movements to reading lines on an eye chart,” said Dr Albert Maguire of Children’s Hospital. Only one eye was treated, the other eye was then used as a “control” to tell whether vision had improved.
The next stage of testing will involve treating children, whose eyes have deteriorated less and who have a better chance of improving.
Gene therapy is a contentious issue and the research teams had to prove that the virus does not leave the eye. In 2002 two French boys were cured of their immune disorder, but ended up with leukemia and in 1999 an American teenager died.
Retina SA have hailed the breakthrough as being of Biblical significance and are looking for young South Africans affected by LCA to check if they have the same gene mutation as the patients in the new studies.
Claudette Medefindt, Director for Science, Retina SA says, “The gene therapy will only work in a specific gene – the RPE65 gene and not on other LCA genes. Gene tracking is critical to identify all young South Africans who may benefit from these
ground breaking trials.”
And they have put their money where their mouth is, funding the Gene Tracking Project at the University of Cape Town.