Intrafamilial variability of Parkinson phenotype in SCAs: Novel cases due to SCA2 and SCA3 expansions

M. P. Socal, V. E. Emmel, C. R.M. Rieder, A. Hilbig, M. L. Saraiva-Pereira, L. B. Jardim

Research output: Contribution to journalArticlepeer-review


Background: Parkinson's disease (PD) has been related to mutations associated with spinocerebellar ataxias (SCA); the frequency of the diagnosis of these mutations is low in general late-onset PD cases. Our aim was to investigate a selected high-risk group of PD patients. Methods: PD patients with autosomal dominant inheritance or atypical neurological manifestations were enrolled, underwent a full neurological examination and had the CAG tracts of their SCA1, 2, 3, 6 and 7 genes analyzed. Results: Of the 23 studied families, two SCA3 and one SCA2 cases were identified. All had autosomal dominant inheritance. In the SCA2 pedigree, four affected sibs had a homogeneous PD phenotype. CAG repeats varied between 35 and 44 with CAA interruptions. Intrafamilial phenotypic heterogeneity was identified in the SCA3 pedigrees; parkinsonian and ataxic phenotypes coexisted in both kindreds. CAGn varied between 69 and 71 repeats. Age of onset was lower in the SCA3 patients than in the remaining 24 cases (38 versus 46.7 ± 12 years of age, p = 0.003). Conclusions: SCA2 and SCA3 mutations were detected in 13% of the present sample: the strategy of selecting a high-risk group increased the rate of making these diagnoses. The SCA2 cases confirmed an association between PD and interrupted expansions, as well as PD intrafamilial phenotypic homogeneity. Clinical heterogeneity of SCA3 pedigrees suggests that disease-modifying agents outside the MJD1 gene may play a role in determining PD symptoms in this disorder.

Original languageEnglish (US)
Pages (from-to)374-378
Number of pages5
JournalParkinsonism and Related Disorders
Issue number5
StatePublished - Jun 2009
Externally publishedYes


  • Dominant inheritance
  • Parkinson's disease
  • SCA2
  • SCA3
  • Spinocerebellar ataxia

ASJC Scopus subject areas

  • Neurology
  • Geriatrics and Gerontology
  • Clinical Neurology


Dive into the research topics of 'Intrafamilial variability of Parkinson phenotype in SCAs: Novel cases due to SCA2 and SCA3 expansions'. Together they form a unique fingerprint.

Cite this