Gene therapy is a new form of treatment that involves adding, removing or editing genes in your cells. Almost every cell of your body contains your DNA, and your DNA is made up of hundreds of thousands of genes which make you unique.
However, genes can become changed, and these mutated genes can cause cells to behave abnormally or die. The mutated genes can also be passed on to children.
Genetic causes of macular disease
Many macular dystrophies, such as Stargardt disease, Best disease and Sorsby Fundus dystrophy, are due to a mutation in a single gene. These diseases are often seen to run in families; children may inherit the faulty gene from either their mother or father.
The faulty gene can lead to the cells in the macula not functioning correctly, or can cause cell death, therefore leading to vision loss.
However, through gene therapy, researchers are hoping to be able to stop the effects of the mutation by fixing, removing or replacing the faulty gene with a healthy copy of the gene.
Research funded by the Macular Society is looking into this for both Stargardt disease with Professor McLaren and Best disease with Dr Amanda Carr.
Using gene editing to stop progression of Stargardt disease
In Stargardt disease, mutations in the ABCA4 gene lead to damage to the macula. This work aims to create healthy ABCA4 protein using gene editing.
Switching off the genes that cause Best disease
Researching using a new gene editing technique to turn off the faulty gene that causes vision loss in Best disease.
Gene Therapy and AMD
We also know that genetics play a part in the risk of developing age-related macular degeneration (AMD). However, lifestyle factors are also involved in the risk of developing AMD and how fast the disease progresses.
As there is not one single faulty gene causing AMD, it is not as simple to fix any genetic mutations, compared to the macular dystrophies. Instead, researchers are looking at creating a ‘drug factory’ in the eye using gene therapy, as a treatment for AMD.
Researchers are investigating adding a gene to the cells of the macula that is the code to make a drug. A virus is used to ‘infect’ the cells and insert the gene, which means that the eye is able to produce the drug for itself. For patients with wet AMD who receive frequent anti-VEGF injections, a single injection of a gene may be preferable to regular eye injections.
Current Stage of Gene Therapy
Unfortunately, gene therapies for macular dystrophies and AMD are still in the early stages of research, and we do not yet know when they will be widely available. You can find more information about the clinical trial process and research in Take Part in Research.