Ataxia with oculomotor apraxia type 1

Ataxia with oculomotor apraxia type 1 (AOA1), also known as early-onset ataxia with ocular motor apraxia and hypoalbuminemia, is a rare autosomal recessive disorder caused by mutations in the APTX gene. AOA1 usually begins as uncoordinated movements and ataxia at the age of four but can start manifesting between ages two and ten. Also, they develop oculomotor apraxia, dysarthric speech, myoclonic jerks, chorea, cognitive impairment, and neuropathy. Elevated levels of cholesterol, creatine kinase, and decreased levels of albumin can be seen. Patients usually start using wheelchair after 11 years since the onset of the symptoms.

APTX gene codes for the protein Aprataxin, which might help DNA repair by the removal of adenylate groups from 5′-phosphate terminus at single-strand DNA nicks and gaps. It is most common in Japan and Portugal.

Symptoms

In AOA1, patients usually experience oculomotor apraxia, problems with innitiation (oculocephalic dissociation) and slowing of saccades, nystagmus, failure of fixation, excessive blinking, ataxia, tremor, neuropathy (which leads to hyporeflexia, diminished sense of vibration, and limb weakness), atrophy of the cerebellum, decreased levels of albumin and elevated levels of cholesterol, dysarthric speech, chorea (which might disappear as disease progresses). Occasionally, patients experience scoliosis, intellectual disability, dystonia, head thrust, elevated levels of creatine kinase and alpha-fetoprotein. Rarely, patients experience parkinsonism, myoclonic jerks, and pyramidal signs.