Spinocerebellar Ataxia-Type 7

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


Spinocerebellar ataxia-type 7 (SCA7) is a progressive autosomal dominant neurodegenerative disorder characterized by cerebellar ataxia associated with progressive macular dystrophy. The disease primarily affects the cerebellum and retina and is caused by expansion of an unstable trinucleotide CAG repeat on chromosome 3 which encodes a polyglutamine tract in the corresponding protein, ataxin-7. Pathological alleles contain from 36 to 306 CAG repeats. The clinical hallmark of SCA7 is the association of hereditary ataxia together with progressive visual loss caused by pigmentary macular degeneration. This association represents a distinct disease entity originally classified as an autosomal dominant cerebellar ataxia type II by Anita Harding.


Cerebellar Ataxia Polyglutamine Tract Clinical Hallmark Hereditary Ataxia Distinct Disease Entity 
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Supplementary material

Clip 1: examination of the index patient shows mild cerebellar dysfunction with slight finger-nose ataxia, normal rapid alternating movements, a mildly wide-based gait, and difficulty with tandem gait. Clip 2: examination of the index patient’s nearly blind son shows ophthalmoplegia in all directions of gaze with difficulty generating saccadic and pursuit eye movements. Rapid alternating hand movements are slow, and severe finger-nose ataxia is present which appears at least in part due to poor vision. There was severe truncal and gait ataxia requiring assistance with walking.

SCA type 7.mp4 (MP4 65,548KB)


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    Harding AE. The clinical features and classification of the late onset autosomal dominant cerebellar ataxias: a study of 11 families, including descendants of the ‘the Drew family of Walworth’. Brain. 1982;105:1–28.PubMedCrossRefGoogle Scholar
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    Enevoldson TP, Sanders MD, Harding AE. Autosomal dominant cerebellar ataxia with pigmentary macular dystrophy. A clinical and genetic study of eight families. Brain. 1994;117:445–60.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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