Spinocerebellar Ataxia-Type 3

  • Roongroj Bhidayasiri
  • Daniel Tarsy
Part of the Current Clinical Neurology book series (CCNEU)


Spinocerebellar ataxia-type 3 (SCA3) or Machado-Joseph disease (MJD) is a clinically heterogeneous, neurodegenerative disorder characterized by varying degrees of ataxia, ophthalmoplegia, peripheral neuropathy, pyramidal dysfunction, and movement disorder. It is the most common SCA with a worldwide distribution and, contrary to early reports, is not limited to individuals of Azorean ancestry. MJD/SCA3 is caused by CAG repeat expansion mutations in the protein coding region of the ATXN3 gene located at chromosome 14q32.1. Expanded CAG repeat lengths correlate with the range and severity of clinical manifestations and inversely correlate with age of disease onset.


Smooth Pursuit Cerebellar Ataxia Early Onset Patient ATXN3 Gene Blink Frequency 
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Supplementary material

There is facial masking and marked right laterocollis. He exhibits severe intention tremor together with a milder tremor at rest. Finger-nose testing is difficult due to severe tremor and ataxia. Pursuit eye movements are absent and he is unable to protrude his tongue.

SCA type 3.mp4(MP4 27,073KB)


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    Kawaguchi Y, Okamoto T, Taniwaki M, et al. CAG expansions in a novel gene for Machado-Joseph disease at chromosome 14q32.1. Nat Genet. 1994;8:221–8.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2012

Authors and Affiliations

  • Roongroj Bhidayasiri
    • 1
    • 2
  • Daniel Tarsy
    • 3
  1. 1.Chulalongkorn Center of Excellence on Parkinson’s Disease and Related DisordersChulalongkorn University HospitalBangkokThailand
  2. 2.Department of NeurologyDavid Geffen School of Medicine at UCLALos AngelesUSA
  3. 3.Department of NeurologyHarvard Medical School Beth Israel Deaconess Medical CenterBostonUSA

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