The retina lining the inside of the eye responds to light by generating electrical signals and sending them to the brain which enables us to see. The retina is a highly complex tissue with multiple cell types that processes the light signals to some extent before sending them on. Many genes, of which we know only a few, lead to retinal dysfunction as in the disease described here.
Otherwise healthy individuals first become symptomatic between the ages of 25 and 40 years when they become more sensitive to light. Over a period of some years vision gradually decreases and older persons may become legally blind. General health, though, remains good. Older individuals have mild color vision problems.
An eye examination by an ophthalmologist reveals rather subtle changes in the appearance of the retina. The optic nerve can appear abnormally pale. The electroretinogram (ERG) is a sensitive way of measuring the responses of the rods and cones (the cells that respond to light) and is abnormal in this condition.
This is an autosomal dominant condition with a vertical pattern of inheritance. Thus, affected parents can expect that half of their children will inherit the same condition. It has been reported in a single large family in which three generations were affected.
The gene product is associated with the abnormal protein plaques found in the brain in Alzheimer disease but no dementia was present in the reported family.
This condition can be diagnosed by an ophthalmologist. No systemic disease is present and longevity is normal. Dark glasses or some form of tinted lenses might be helpful for light-sensitive individuals. Low vision aids should be beneficial for patients with significant reading problems.