Clinical and molecular features of spinocerebellar ataxia type 6

Neurology. 1997 Nov;49(5):1243-6. doi: 10.1212/wnl.49.5.1243.


The mutation involved in spinocerebellar ataxia type 6 (SCA6) is a small CAG expansion in the alpha-1A subunit of the voltage-dependent calcium channel gene. We looked for this mutation in 91 families with autosomal-dominant cerebellar ataxias and found that SCA6 is a minor locus in our series (2%) and is rare in France (1%). Furthermore, we did not detect the SCA6 mutation on 146 sporadic cases with isolated cerebellar ataxia or olivopontocerebellar atrophy. The normal and expanded alleles ranged from 4 to 15 and 22 to 28 CAG repeats, respectively, and age at onset was correlated to CAG repeat length (r = -0.87). In contrast with other SCA, the expanded allele was stable during transmission. Clinically, SCA6 patients (n = 12) presented with moderate to severe cerebellar ataxia with a lower frequency of associated signs compared with other SCA and a mean age at onset of 45 +/- 14 years (range, 24 to 67). MRI showed extensive cerebellar atrophy but not of the brainstem or cerebral cortex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Age of Onset
  • Aged
  • Alleles
  • Family Health
  • Female
  • Gene Frequency
  • Genotype
  • Humans
  • Male
  • Middle Aged
  • Mutation
  • Pedigree
  • Spinocerebellar Degenerations / diagnosis*
  • Spinocerebellar Degenerations / genetics*
  • Trinucleotide Repeats*