Choroideremia is a genetic disease that affects about 1 newborn every 50,000-100,000, especially males. The disease manifests itself in the first 10 years of life with a progressive narrowing of the peripheral visual field. Before the age of 40, complete vision loss and subsequent blindness occur.
In the choroideremia the progressive degeneration occurs of:
retinal pigment epithelium
The latter are the cells placed at the back of the eye, which collect light.
The first symptom of choroideremia is the lowering of vision in low light conditions. The lack of photoreceptors makes it difficult to collect the little light available in the environment. Then the visual field begins to shrink and leads to the so-called tubular vision. In adult age this translates into total loss of sight. It usually happens around the age of 40, but the timing may change depending on the patient's condition.
Progressive loss of vision remembers what happens in other types of retinal degeneration, such as X-linked retinitis pigmentosa or turned atrophy. This complicates the diagnosis, especially if there are no cases known in the family. The assessment of the fundus of the eye and the dosage of ornithine levels can help to obtain a more precise diagnosis, but not always enough. Genetic tests can be used to confirm the diagnosis.
The disease is caused by the mutated version of the CHM gene, which encodes the REP-1 protein. About 20% of patients do not show the mutation, so it is likely that there are other genes involved.
For the moment there are no definitive therapies. The only possible treatment is to make the most of the visual function, also thanks to technical support for low vision. These have helped and help many patients to lead an almost normal life, although unfortunately there is still no way to stop the progression of the disease.