Ocular Motor Apraxia Type 2

Ocular motor apraxia type 2 (AOA2) is an autosomal recessively inherited disease caused by mutations in the SETX gene. The encoded protein Sentaxin has been identified as a helicase involved in DNA repair and defects probably lead to an accumulation of DNA damage in cells ultimately causing cell death.

Signs and Symptoms

The typical age of onset of AOA2 lies between 3 and 30 years. Characteristic symptoms include high-grade axonal sensorimotor neuropathy, ocular motor apraxia and high concentrations of alpha-fetoprotein. 

Diagnosis

Neurological examinations, biochemical findings and family history form the basis for diagnosis of AOA2. Ocular motor examination reveals hypometric saccades with a typical staircase pattern often accompanied by compensatory head thrust movements.

Observable ocular motor disorders

  • Hypometric saccades with staircase pattern

References

Strupp M, et al. (2014) Central ocular motor disorders, including gaze palsy and nystagmus. J Neurol 261(2):542-558. PubMed

GeneReviews: Ataxia with Oculomotor Apraxia Type 2, Maria-Ceu Moreira, Michel Koenig, last update December 8, 2011 http://www.ncbi.nlm.nih.gov/books/NBK1154/