SCA27B in Brazil: frequency, phenotype and genotype-phenotype correlations
Amanda de Jesus Araujo Dias1, Cynthia Silveira1, Adriana Mendes Vinagre1
1Department of Neurology, School of Medical Sciences, University of Campinas (UNICAMP), Rua Tessália Vieira de Camargo, 126, Cidade Universitária "Zeferino Vaz", Campinas, São Paulo, 13083-887, Brazil.
Journal of Neurology
|May 21, 2026
Summary
Spinocerebellar Ataxia 27B (SCA27B) is a prevalent ataxia in Brazil, found in 2.8% of cases. Its clinical presentation is similar to other populations, with age at onset potentially indicating prognosis.
Area of Science:
- Genetics
- Neurology
- Rare Diseases
Background:
- Spinocerebellar Ataxia 27B (SCA27B) is an autosomal dominant ataxia caused by FGF14 gene expansions.
- It is a common subtype in North America and Europe, but its prevalence in Latin America is unknown.
Purpose of the Study:
- To determine the frequency of SCA27B in a Brazilian Spinocerebellar Ataxia (SCA) cohort.
- To characterize the clinical phenotype of SCA27B in this population.
Main Methods:
- Recruited 498 SCA patients from 322 families.
- Collected demographic and clinical data, calculating disease progression rate using the SARA score.
- Utilized PCR-based genetic testing for SCA1, 2, 3, 6, 7, and SCA27B.
Main Results:
- SCA27B was identified in 2.8% of index patients (9/322), making it the fifth most common SCA in Brazil.
- The phenotype included late onset (mean 55.5 years), slow progression (1.0 point/year), and primarily ataxic symptoms.
- Disease progression correlated with age at onset, but not with (GAA)n repeat length.
Conclusions:
- SCA27B is prevalent in Brazil, though less frequent than in Europe/Canada.
- SCA27B should be incorporated into routine diagnostic protocols for SCAs.
- Age at onset may serve as a prognostic marker for SCA27B.
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