SCA2 is an autosomal dominantly inherited disease where the ataxin-2 protein (ATXN2 gene) is affected by the polyQ expansion. 

Signs and Symptoms

Retinitis pigmentosa progressing from night blindness to total blindness and myoclonic epilepsy can be signs of SCA2. The major ocular motor symptom is an early, isolated slowing of horizontal saccades with an impairment of vertical saccades.


Neurological examination including an eye movement examination is vital for the diagnosis of SCA. Molecular genetic testing to detect an abnormal CAG extension in one of ATXN genes used to rule out any other causes for the neurological findings.

Observable ocular motor disorders

  • Horizontal supranuclear gaze palsy
  • Slowing of horizontal saccades (SCA7)


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

Seidel K, et al. Brain pathology of spinocerebellar ataxias. Acta Neuropathol., 2012, 124(1):1-21. PubMed

Lastres-Becker I, et al. Spinocerebellar ataxia 2 (SCA2). Cerebellum, 2008 7(2):115-124. PubMed