Retinitis Pigmentosa 78

Background and History: 

The retina of the eye has many cell types, among them the rods and cones that respond to light and transmit the impulses to the brain.  The many biochemical reactions in the rods and cones are under gene control and mutations in these are responsible for a large number of hereditary eye disorders.  Among these are a group of conditions collectively called retinitis pigmentosa which resemble each other clinically so closely that gene studies are necessary to distinguish them.

Clinical Correlations: 

Individuals with this form of retinitis pigmentosa become symptomatic around the third or fourth decades of life with difficulty seeing in dim light (night blindness), disturbances in visual acuity, and they may note constriction of their peripheral field of vision.  This condition is progressive and symptoms worsen with aging.

The changes in the retina are typical for retinitis pigmentosa with characteristic pigment clumping, narrowing of retinal blood vessels, paleness of the optic nerve, and general deterioration of the retina.

Genetics: 

This is likely an autosomal recessive condition based on the gene changes (mutations) present.  Three unrelated individuals have been reported, all of whom had mutations in the same gene.  Family members with only one copy of the mutation did not have clinical disease.  However, no direct family transmission pattern of the retinal disease is available to corroborate this.

In autosomal recessive disorders, the parents who carry a single gene change are usually normal clinically but two such carrier parents confer a 25% risk for this condition to each of their offspring. 

Diagnosis and Prognosis: 

The diagnosis is made by direct examination of the retina and requires a medical eye doctor: an ophthalmologist.  Special testing such as visual fields and an ERG (electroretinogram) is usually done.  This, however, can only detect the category of disease and gene testing is necessary to determine which specific condition is actually present.

This condition has no impact on health outside of the eye.  The actual visual acuity is highly variable and unpredictable.

No treatment has been reported.  However, low vision aids might be helpful especially for near or reading vision.

There is no known impact on general health or longevity.

Additional Information
Inheritance/Pedigree: 
Autosomal recessive