Leber’s Congenital Amaurosis (LCA)
What is Leber’s Congenital Amaurosis (LCA)?
Leber’s Congenital Amaurosis (LCA) is an inherited retinal disease that causes visual loss in the first months of life. It is inherited as a recessive trait, meaning both the mother and father must have an inactive copy of the gene that they give to the child. When two of the genes are together, LCA manifests. Because LCA is a recessive condition, there is often no family history of the disease, which makes LCA difficult for families to anticipate.
Often, retinal regions affected by the defective genes show up as abnormal pigment in the retina.
An infant with LCA will have nystagmus, or rhythmic movements of the eyes back and forth beginning in the first few months of life. This type of movement occurs in infants that lose vision in both eyes from any disease, and must be distinguished from other possibilities such as congenital cataracts and retinopathy of prematurity.
The retina usually looks normal at this stage.
LCA is actually a group of diseases associated with abnormal photoreceptor cells, so there is variation in presentation and severity.
How do we treat LCA?
Many of the genes that cause LCA have been identified. Once the gene responsible for a condition has been identified, the condition may be treated by gene therapy.
For instance, one type of LCA known as LCA2 was found to be caused by a mutation in the gene RPE65, and it has been successfully treated with gene replacement therapy. A functional copy of gene RPE65 is injected into the subretinal space via a viral vector with a promoter gene sequence. The results have been encouraging, as many patients undergoing the treatment have stable or improved vision.
However, this treatment must be done early in the course of the disease before the retinal cells are damaged irreversibly. For those who have grown up with LCA, this is not a viable treatment.