Neurologic conditions are often associated with ataxia, or difficulties with balance and unsteadiness. Other symptoms are almost always present depending upon which brain structures are involved in the disease. In this disorder, patients have difficulty moving their eyes in addition to having other neurologic symptoms.
The first symptoms consisting of difficulty with balance and walking are often seen by the end of the first decade of life but sometimes not until the third decade. They often develop slurred speech and lose reflexes in the limbs. Patients have difficulty initiating voluntary eye movements upon command or following targets (apraxia). Some individuals have decreased sensation in the limbs and close inspection may reveal fine twitching movements in muscles. There may also be fine involuntary movements of the hands and fingers. Muscular weakness and some wasting may be present. Sensory functions such as touch is often impaired as well. Mental function is usually normal although there may be some decline in cognition in older individuals. There may be a decrease of the albumin protein in the blood and increased cholesterol can be present. Walking difficulties often confine patients to a wheelchair by the fourth decade of life. Blood cholesterol is sometimes elevated and a protein known as alpha-fetoprotein is likewise increased in blood serum.
This is an autosomal recessive condition resulting from a DNA change (mutation) in both copies of a gene. Parents with one copy are usually normal but they can expect that each child will have a 25% chance of inheriting this condition.
The diagnosis is usually made by a neurologist who may collaborate with an ophthalmologist to document the eye movement problem. An MRI can demonstrate some wasting of certain brain structures. Longevity is mildly reduced. Physical and speech therapy can be helpful in early stages of the disease and special education may be useful.