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There are several causes of congenital blindness that are often the result of mutated or defective genes. Gene therapy is a targeted treatment that is showing serious promise in helping to reverse cases of congenital blindness related to defective or mutated genes. (Learn More)
Gene therapy is a relatively novel approach that works in one of two ways. It either aims to replace the defective gene completely (Learn More) or to correct the gene mutations by altering the genetic code. (Learn More)
Research is ongoing with gene therapy. There are a lot of potential uses in helping to restore vision and potentially cure congenital blindness. (Learn More)
Promising Gene Therapy for Congenital Blindness
Congenital means something you are born with that is often inherited.
Leber congenital amaurosis (LCA) is one of the most common causes of blindness in newborns, occurring in between 2 and 3 out of every 100,000 births. About 80 to 90 percent of infants born with this condition have genetic mutations that cause the light-gathering cells in the retina to malfunction.
Another common cause of congenital blindness is retinitis pigmentosa. This is also often caused by genetic mutations.
Gene therapy can target the affected genes in one of two main ways. It can either replace the defective or mutated gene with a healthy one, or it can be used to correct the genetic code to fix gene mutations.
Gene therapy is showing promise in clinical trials for treating retinitis pigmentosa and also LCA by improving functional vision.
Replacing the Defective Gene
In 2017, the FDA approved a new gene therapy called Luxturna (voretigene neparvovec) that targets the gene RPE65, which is often defective or mutated in people with congenital blindness caused by LCA or retinitis pigmentosa. This type of gene therapy replaces the defective gene that helps code for a protein, aiding the production of chemical reactions necessary for the retina to detect light.
This new gene therapy has worked to restore functional vision in those with congenital blindness, helping them to be able to detect light better and navigate obstacle courses. However, it is not yet a permanent fix.
Correcting Gene Mutations
Another strategy of gene therapy is to target the genetic code itself. This therapy aims to alter it to correct for the mutations to the genes caused by disease. This type of gene therapy works by activating genes that have similar functions to the ones that are mutated and not working properly.
Studies are being done to test the Cas9-VPR system of gene therapy into the retinal cells directly. This helps to slow the progression of retinal degeneration that occurs with diseases like retinitis pigmentosa, which is progressive.
This therapy is a derivative of the CRISPR approach that is used to target gene mutations responsible for childhood blindness. This form of gene therapy seems to also have a protective effect, leading to less retinal degeneration across the board, not just in the targeted area.
Future of Treatments
Gene therapy is still relatively new. Currently, there are numerous clinical trials being done to test its safety and efficacy in treating congenital blindness, with the hopes of finding a more permanent fix and eventual cure. Gene therapy can help to reverse some of the effects of disease-causing retinal damage by activating other areas of genetic code or by replacing defective genes.
Many diseases causing congenital blindness are progressive. If they are caught early enough, it may be possible to slow or even stop the degeneration of the retina with these targeted and specialized approaches.
Congenital Blindness and Vision Impairment Cause Infection or Non Infection. (2013). Materia Socio-Medica.
Leber Congenital Amaurosis. (2020). National Organization for Rare Disorders (NORD).
Initial Results From a First-in-Human Gene Therapy Trial on X-Linked Retinitis Pigmentosa Caused by Mutations in RPGR. (February 2020). Nature Medicine.
FDA Approves Novel Gene Therapy to Treat Patients With a Rare Form of Inherited Vision Loss. (December 2017). U.S. Food and Drug Administration (FDA).
Gene Therapies and CRISPR Strategies for Curing Blindness. (June 2020). UMASS Med News.
Retinitis Pigmentosa Research Advances. (September 2020). Foundation Fighting Blindness.