Ataxia-oculomotor apraxia type 1

Ataxia-oculomotor apraxia type 1 (AOA1), also known as early-onset ataxia with oculomotor apraxia and hypoalbuminemia (EAOH), is a rare autosomal recessive neurodegenerative disorder caused by mutations in the APTX gene, which encodes the protein aprataxin. Aprataxin plays a critical role in DNA single-strand break repair, and its deficiency leads to progressive neurological deterioration. The disease primarily affects the nervous system, with onset typically occurring in childhood, most commonly between ages 2 and 6 years. The hallmark features of AOA1 include progressive cerebellar ataxia (difficulty with coordination and balance), oculomotor apraxia (difficulty initiating voluntary eye movements), and peripheral neuropathy. Cerebellar atrophy is a consistent finding on brain imaging. Patients often develop choreoathetosis (involuntary movements) early in the disease course, which may later diminish as the ataxia worsens. Peripheral neuropathy, predominantly axonal sensorimotor in nature, contributes to limb weakness and loss of deep tendon reflexes. Cognitive impairment may occur in some patients but is variable. Characteristic laboratory findings include hypoalbuminemia (low blood albumin levels) and hypercholesterolemia (elevated cholesterol), which are important diagnostic clues. There is currently no cure or disease-modifying treatment for AOA1. Management is supportive and symptomatic, involving physical therapy and rehabilitation to maintain mobility, occupational therapy, speech therapy for dysarthria, and orthopedic interventions as needed. Monitoring of nutritional status and cholesterol levels is recommended. Most patients become wheelchair-dependent within 10 to 15 years of disease onset. AOA1 is particularly prevalent in Portugal and Japan but has been reported worldwide.

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