Spinocerebellar ataxia type 10 in the South of Brazil: the Amerindian-Belgian connection / Ataxia espinocerebelar tipo 10 no sul do Brasil: a conexão Ameríndia-Belga

Spinocerebellar ataxia type 10 (SCA10) is a rare form of autosomal dominant ataxia found predominantly in patients from Latin America with Amerindian ancestry. The authors report the history of SCA10 families from the south of Brazil (the states of Paraná and Santa Catarina), emphasizing the Belgian-Amerindian connection.

A ataxia espinocerebellar tipo 10 (AEC10) é uma forma rara de ataxia cerebelar autossômica dominante, encontrada predominantemente em pacientes da América Latina, de origem Ameríndia. Os autores relatam a história de famílias com AEC10 do sul do Brasil (estados do Paraná e Santa Catarina), enfatizando a conexão Ameríndia-Belga.

Spinocerebellar ataxias: genotype-phenotype correlations in 104 Brazilian families

OBJECTIVE: Spinocerebellar ataxias are neurodegenerative disorders involving the cerebellum and its connections. There are more than 30 distinct subtypes, 16 of which are associated with an identified gene. The aim of the current study was to evaluate a large group of patients from 104 Brazilian families with spinocerebellar ataxias. METHODS: We studied 150 patients from 104 families with spinocerebellar ataxias who had received molecular genetic testing for spinocerebellar ataxia types 1, 2, 3, 6, 7, 8, 10, 12, 17, and dentatorubral-pallidoluysian atrophy. A statistical analysis of the results was performed using basic descriptive statistics and the correlation coefficient (r), Student's t-test, chi-square test, and Yates' correction. The statistical significance level was established for p-values <0.05. RESULTS: The results show that the most common subtype was spinocerebellar ataxia 3, which was followed by spinocerebellar ataxia 10. Moreover, the comparison between patients with spinocerebellar ataxia 3, spinocerebellar ataxia 10, and other types of spinocerebellar ataxia revealed distinct clinical features for each type. In patients with spinocerebellar ataxia 3, the phenotype was highly pleomorphic, although the most common signs of disease included cerebellar ataxia (CA), ophthalmoplegia, diplopia, eyelid retraction, facial fasciculation, pyramidal signs, and peripheral neuropathy. In patients with spinocerebellar ataxia 10, the phenotype was also rather distinct and consisted of pure cerebellar ataxia and abnormal saccadic eye movement as well as ocular dysmetria. Patients with spinocerebellar ataxias 2 and 7 presented highly suggestive features of cerebellar ataxia, including slow saccadic ocular movements and areflexia in spinocerebellar ataxia 2 and visual loss in spinocerebellar ataxia 7. CONCLUSIONS: Spinocerebellar ataxia 3 was the most common subtype examined, followed by spinocerebellar ataxia 10. Patients with spinocerebellar ataxia 2 and 7 demonstrated highly suggestive features, whereas the phenotype of spinocerebellar ataxia 3 patients was highly pleomorphic and spinocerebellar ataxia 10 patients exhibited pure cerebellar ataxia. Epilepsy was absent in all of the patients with spinocerebellar ataxia 10 in this series.