ataxia with oculomotor apraxia type 1
ataxia with oculomotor apraxia type 1A condition characterised by childhood onset of slowly progressive cerebellar ataxia, followed by oculomotor apraxia and a severe primary motor peripheral axonal motor neuropathy. The first manifestation is progressive gait imbalance at age 4–5, followed by dysarthria, upper-limb dysmetria and intention tremor. This is followed by oculomotor apraxia, which progresses to external ophthalmoplegia, generalised areflexia, peripheral neuropathy and quadriplegia 7–10 years after onset. The hands and feet are short and atrophic; chorea and upper-limb dystonia are common; cognition may or may not remain intact.
Missense mutations of APTX, which encodes aprataxin, a protein that plays a role in DNA-single-strand break repair.