Epidemiology of Autosomal Dominant Spinocerebellar Ataxias in Latin America: A Systematic Review and Meta-Analysis.

The Spinocerebellar Ataxias (SCAs) are a group of autosomal dominant neurodegenerative disorders characterized by progressive cerebellar ataxia, affecting motor coordination. SCAs are reported globally with large geographical and ethnic differences. This systematic review and meta-analysis aimed to update the frequency, and geographic distribution of SCAs in Latin America, including recently identified SCAs like SCA27B. We conducted a systematic search in PubMed, Scopus, LILACS, SciELO, and Web of Science databases, including studies published from inception to January 2025. We included 27 studies for the systematic review and 18 studies for the meta-analysis that met the inclusion criteria, representing a total of 5859 participants across eleven countries. Our meta-analysis revealed that about 50% (95% CI 26-74%) of hereditary ataxias in Latin America were confirmed to have a genetic diagnosis of SCA. The included participants with a known SCA have the following proportions: MJD/SCA3 (15%), SCA2 (11%), SCA7 (4%), SCA10 (3%), and SCA1 (3%). Geographic distributions were notable, MJD/SCA3 in Brazil, SCA2 in Cuba, Argentina and Mexico, SCA10 predominating in Peru, and SCA7 in Venezuela. Recently identified SCA types, like SCA27B and one case of SCA4, were identified in Brazil. In 22 countries there are no published studies on the epidemiology of SCAs. The distribution of SCAs in Latin America reflects the influence of historical migrations, founder effects, and ancestries, emphasizing regional heterogeneity. Our findings underscore the critical need for further epidemiological studies, particularly in understudied countries in the region.