This rare inherited progressive neurological condition primarily affects physical movement, speech, and eye movements. Only three families have been reported.
The first sign is usually nystagmus (small jerky eye movements) and it is frequently seen in the first year of life. There may be limitation in looking up. Unsteadiness is a common early sign and some patients require a wheelchair later in life as the disease progresses. Stiffness (spasticity), especially of the lower limbs) is often present. Speech is frequently slurred. Most patients have normal cognition and mental function but two patients in one family had developmental delays. Many individuals have slow purposeless limb movements.
MRIs of the brain have revealed underdevelopment of parts of the brain.
This is an autosomal recessive disorder resulting from a change (mutation) in both members of a specific pair of genes for the disease to be evident. The carrier parents with a single mutation are clinically normal but the offspring of two such parents have a 25% risk of inheriting this condition.
Neurologists and ophthalmologists are likely to collaborate in the diagnosis of this disorder. There are no evident physical signs (other than the nystagmus which occurs in other conditions as well) and the diagnosis is based on a complete neurological examination and an MRI.
No treatment for the general condition has been reported. Physical therapy and low vision aids may be helpful. Some patients require mobility aids. Nothing is known about longevity in this disorder.