This is a progressive neurological disease with significant ocular signs.
Among the earliest symptoms are developmental delays and failure to thrive. These may appear in the first year of life and with them there is often some loss of vision due to degeneration of the retina. The earlier the onset, the more severe the symptoms and infants with this disorder often do not survive beyond 2 years of age. Children often regress neurologically with loss of motor milestones such as sitting and walking. Unsteadiness (ataxia) is a major problem. Speech and swallowing difficulties are common.
Others may not show symptoms until adolescence or even until adulthood and such individuals live much longer, even into the 5th or 6th decades of life. All individuals exhibit severe loss of vision with problems in color perception and many become blind. Some patients have difficulties moving their eyes rapidly. Walking and fine movements become increasingly difficult and many become confined to a wheelchair.
This is an autosomal dominant disorder inherited in a vertical pattern. Parents with the disease can expect on average that half of their children will inherit the disease. There is a tendency for succeeding generations to have more severe disease with an earlier onset, a phenomenon known as genetic anticipation. Sometimes the diagnosis is made in a child before the parents or grandparents are diagnosed.
Neurologists and ophthalmologists working together usually can make this diagnosis, especially if there is a family history. No treatment is available for this disease but low vision aids and mobility training can be helpful in early stages.