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Disease characteristics

Excerpted from the GeneReview: Spinocerebellar Ataxia Type 6
Spinocerebellar ataxia type 6 (SCA6) is characterized by adult-onset, slowly progressive cerebellar ataxia, dysarthria, and nystagmus. Mean age of onset is 43 to 52 years. Initial symptoms are gait unsteadiness, stumbling, and imbalance (in ~90%) and dysarthria (in ~10%). Eventually all persons have gait ataxia, upper-limb incoordination, intention tremor, and dysarthria. Dysphagia and choking are common. Visual disturbances may result from diplopia, difficulty fixating on moving objects, horizontal gaze-evoked nystagmus, and vertical nystagmus. Hyperreflexia and extensor plantar responses occur in up to 40%-50%. Basal ganglia signs, including dystonia and blepharospasm, occur in up to 25%. Mentation is generally preserved.

Associated genes

  • Also known as: APCA, BI, CACNL1A4, CAV2.1, EA2, FHM, HPCA, MHP, MHP1, SCA6, CACNA1A
    Summary: calcium channel, voltage-dependent, P/Q type, alpha 1A subunit

Clinical features

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  • Impaired smooth pursuit
  • Dysarthria
  • Dysphagia
  • Progressive cerebellar ataxia
  • Gaze-evoked nystagmus
  • Sensory neuropathy
  • Cerebellar atrophy
  • Migraine
  • Abnormal vestibulo-ocular reflex
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