Retinitis Pigmentosa 42
Patient Information
Characteristics
Background and History
Retinitis pigmentosa (RP) consists of a large group of disorders resulting from a progressive loss of the rods and cones in the retina. These are the cells that respond to light and send signals to the brain that enable us to see. More than 150 mutant genes have been identified as responsible for these hereditary disorders and there is considerable variation in onset and progression of symptoms. The disease usually is present as an isolated eye disease but syndromal forms also occur in which there is a similar disease of the retina in association with other problems elsewhere in the body.
The type described here is later in onset and more slowly progressive than many other forms.
Clinical Correlations
Difficulty seeing in dim light is a prominent symptom although its age of onset is unknown. The presenting complaint is usually loss of side vision as the peripheral field of vision constricts leading to “tunnel vision”. Noticeable loss of central vision (mediating visual acuity) may not be evident until the age of 50 years and is only slowly progressive over several decades. The progress is highly variable, however, and some individuals retain normal or near normal vision into the 7th decade.
Individuals with this condition are otherwise healthy.
Genetics
Inheritance
This condition is caused by a change (mutation) in a specific gene and the eye findings are passed directly from an affected parent to each child with a 50% probability.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission
Diagnosis and Prognosis
This disorder is diagnosed by an eye doctor (ophthalmologist) through a clinical examination of the eye. An electroretinogram (ERG) confirms the diagnosis but DNA testing for the gene change is necessary to determine the exact type of retinitis pigmentosa.
There is no impact on general health and longevity.
There is no treatment but some patients note an improvement in contrast, comfort, and sharpness of vision with appropriate tinting of glasses.
Web Resources
Printer Friendly Version: Ctrl/Cmd+P