There are many causes of blindness and vision loss, including genetics. Research is under way to develop ways to “fix” errors in the genetic code to give new sight to people with conditions such as retinitis pigmentosa and Leber congenital amaurosis (LCA).
Gene therapy is all about finding ways to fix problems with the body’s genetic code. When a man and woman create a baby, each parent provides half of the genetic information needed for the child to grow and develop. The woman’s genes are represented in her egg while the man’s genes are shared in his sperm. When an egg is fertilized, the genetic code from the woman pairs up with the matching part of the code from the man to create a complete set of instructions for the new baby.
The genetic code is a complex system of triggers that controls every aspect of how the body works, from telling cells whether they should grow into muscles or hair to telling the body how to produce the many chemicals and other substances it needs to function correctly. Because the genetic code is so complex, there are many things that can go wrong. Using gene therapy, scientists are working to figure out what each tiny piece of the code is responsible for and to find ways to fix things in the code when they do go wrong.
In the field of vision, researchers at the University of Pennsylvania are working with dogs that have congenital achromatopsia, which is total color blindness. A similar condition affects about one out of every 30,000 to 50,000 people. This condition results when the cones, or color sensing cells in the retina of the eye do not function correctly. Using gene therapy, the researchers have been able to cure this condition in young dogs, which have a gene structure that is a closer match to human genes than that of the mice which were used in previous studies. The treatment has been effective for over 33 months and appears to be permanent. This successful treatment in dogs brings researchers one step closer to finding a way to use gene therapy to cure this condition in human patients.