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 100 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 as in this condition in which there is a similar disease of the retina in association with other problems elsewhere in the body.
A single family with two boys and one girl has been reported. The earliest symptom seems to be difficulty with night vision late in the first decade of life. Examination reveals pigmentary changes in the retina and cataracts at this time. Daytime vision is only mildly affected at this stage but this likely worsens later. The inside of the eye such as the retina and optic nerves have features typical of retinitis pigmentosa and the electroretinogram (ERG) shows damage to the rods and cones.
These individuals are short in stature and are said to have a characteristic facial appearance with an underdeveloped cheeks and a mildly disfigured nose. The teeth may have wide spaces between them and malocclusion is common. Learning difficulties and developmental delay seem to be part of the syndrome.
The family pattern is consistent with autosomal recessive inheritance. A double gene mutation is responsible. The parents are apparently normal and each contributes a single mutation to their offspring. The risk to each child at conception is 25%.
An ophthalmologist is most likely to diagnose this condition based on an eye examination and an ERG. A pediatrician and a dentist need to be part of the medical team as well. Little is known about the prognosis and no specific treatment is available. However, special education, low vision aids and physical therapy might be beneficial. Surgery should be considered for visually significant cataracts.