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Ataxia with oculomotor apraxia
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Ataxia with oculomotor apraxia

Ataxia with oculomotor apraxia is a group of rare genetic disorders characterized by progressive loss of coordination and difficulty with side-to-side eye movements.

Overview

Ataxia with oculomotor apraxia is a condition characterized by movement problems that worsen over time. The hallmark symptom is ataxia, or poor coordination and balance. Most affected individuals also have oculomotor apraxia, which makes it difficult to move the eyes side-to-side, requiring the person to turn their head to see objects in their peripheral vision.

There are several types of this condition, with types 1, 2, and 4 being the most common. While the types are similar, they are caused by mutations in different genes.

Types and Symptoms

  • Type 1: Begins around age 4. Symptoms include ataxia, oculomotor apraxia, involuntary jerking movements (chorea), or muscle twitches (myoclonus). Individuals may develop muscle wasting in the hands and feet and neuropathy, which impairs reflexes and causes limb weakness.
  • Type 2: Usually begins around age 15. Similar to type 1, it involves ataxia, oculomotor apraxia, chorea, myoclonus, and neuropathy. A key feature is high levels of alpha-fetoprotein (AFP) in the blood.
  • Type 4: Begins around age 4. In addition to ataxia and oculomotor apraxia, individuals typically develop dystonia (involuntary, sustained muscle tensing). Muscle wasting and neuropathy are also common.

Causes

Mutations in the APTX, SETX, or PNKP genes cause types 1, 2, and 4, respectively. These genes provide instructions for proteins involved in repairing damaged DNA. A shortage of these functional proteins leads to the accumulation of broken DNA strands, which can cause cell death. The cerebellum, the part of the brain involved in coordinating movements, is especially at risk, and the loss of brain cells there is thought to cause the characteristic movement problems.

Genes Associated with Ataxia with Oculomotor Apraxia

  • APTX
  • PNKP
  • SETX

Inheritance

All types of this condition are inherited in an autosomal recessive pattern, meaning both copies of the gene in each cell have mutations. Parents of an affected individual each carry one copy of the mutated gene but typically do not show signs or symptoms.

Other Names for This Condition

  • Adult onset ataxia with oculomotor apraxia
  • EAOH
  • Early-onset ataxia with ocular motor apraxia and hypoalbuminemia
  • SCAN2
  • SCAR1
  • Spinocerebellar ataxia with axonal neuropathy type 2
  • Spinocerebellar ataxia, recessive, non-Friedreich type 1

Frequently Asked Questions

Oculomotor apraxia is a neurological deficit in voluntary saccadic eye movements rather than a muscle weakness or retinal disease. Individuals can still move their eyes vertically and retain normal visual sensation, but they cannot swiftly shift their gaze horizontally on command. To compensate and bring peripheral objects into focus, patients reflexively thrust their head past the target so the eyes are forced over by the vestibulo-ocular reflex, followed by a slight head adjustment back to center.
There is currently no cure, making early, multidisciplinary rehabilitation essential. Physical therapy and customized ankle-foot orthoses (AFOs) help counteract gait instability and foot drop caused by peripheral neuropathy. Occupational therapists assist with adaptive feeding tools and writing aids to manage chorea and myoclonus. Speech therapy and formal swallowing assessments (videofluoroscopy) are critical to manage dysarthria and prevent silent aspiration as motor coordination declines.
Diagnosis involves brain MRI, which characteristically reveals progressive cerebellar atrophy, alongside targeted genetic sequencing for the APTX, SETX, and PNKP genes. Specific blood biomarkers provide crucial clues: Type 2 (SETX) is strongly associated with elevated serum alpha-fetoprotein (AFP) levels, whereas Type 1 (APTX) often shows hypoalbuminemia (low blood albumin) and hypercholesterolemia (elevated cholesterol). Nerve conduction studies are also performed to evaluate and document peripheral sensorimotor neuropathy.
taxia with oculomotor apraxia shares clinical features with ataxia-telangiectasia (A-T), a related genetic disorder that carries extreme cellular hypersensitivity to ionizing radiation. Until genetic confirmation rules out classical A-T, clinicians exercise caution and avoid unnecessary diagnostic X-rays or CT scans, prioritizing non-ionizing modalities such as MRI and ultrasound whenever imaging is required.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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