This recently described hereditary disorder is one of a large number of incapacitating neurological conditions. It has so far been reported only in families on the Iberian peninsula. It belongs to a group known as spinocerebellar ataxias (unsteadiness) in which eye movement anomalies occur as well.
The signs of eye movement abnormalities usually occur first and may precede other signs of movement unsteadiness. Irregular eye movements are first apparent when looking up with horizontal movement abnormalities occurring later. The onset of general unsteadiness and clumsiness have their onset at about the age of 50 years and frequent falls are common. Patients may require a wheelchair for mobility within one or two decades of the onset of their disease. Slurred speech and difficulty swallowing are sometimes features as well. No cognitive defects have been reported.
Brain imaging usually shows atrophy (loss of tissue) in the cerebellum.
This is an autosomal dominant disorder in which a single dose of a mutation is transmitted directly from parent to each child with a 50% probability.
This disorder is not diagnosed until midlife. Neurologists and ophthalmologists are likely to collaborate on the diagnosis. There is no known effective treatment but physical therapy is likely to be helpful. Visual acuity has not been reported but since the abnormal eye movements occur primarily upon looking up or to the side, vision in primary (straight ahead) gaze is likely to be nearly normal.
Nothing is known regarding longevity.