Comment on: The Geographic Diversity of Spinocerebellar Ataxias (SCAs) in the Americas.

Abstract

We have read with interest the review by Teive and colleagues1 that described the prevalence and clinical phenotypes of spinocerebellar ataxias (SCAs) across the Americas. The authors showed, based on the results of the so far only study published from a single center in Argentina including 20 patients, that in Argentina the most frequent SCAs were SCA2 (8 cases; 40%) followed by SCA1 and SCA3 (5 cases; 25% for each subtype), SCA6 (1 case; 5%), and SCA7 (1 case; 5%).2 We would like to add unpublished data obtained from the largest genetic and molecular biology center in Argentina from 2008 to 2019. A total of 272 patients with progressive ataxia were tested for SCA1, SCA2, SCA3, SCA6, SCA7, or SCA8. Among the 48 (18%) cases that proved positive for SCA, the most frequent was SCA2 (22 cases; 46%) followed by SCA3 (13 cases; 27%), SCA1 (10 cases; 21%), SCA6 (2 cases; 4%), and SCA7 (1 case; 2%). These results based on a larger cohort confirm Teive and colleagues’1 report that SCA2 is the most frequent genetic subtype in our country, in concordance with Cuba, but different to most countries of the Americas where SCA3 is the most prevalent SCA subtype.1, 3 An explanation for the higher frequency of SCA2 in Argentina in comparison with other SCAs could be because the majority of its people have a European ancestry, mainly from Spain and Italy, where SCA2 is highly prevalent.3 Knowing which SCA subtypes are the most prevalent in different countries or regions is critical for genetic testing when diagnostic resources, such as comprehensive gene panels, are not universally available or affordable. (1) Research Project: A. Conception, B. Organization, C. Execution; (2) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique. M.G.: 1A, 1B, 1C, 2A M.R.: 1A, 1B, 1C, 2A A.Z.: 1A, 1B, 1C, 2B P.I.: 1A, 1B, 1C, 2B Ethical Compliance Statement: We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines. The authors confirm that the work received approval of an institutional review board. Funding Sources and Conflicts of Interest: The authors declare that there are no conflicts of interest relevant to this work. Financial Disclosures for Previous 12 Months: The authors declare that there are no additional disclosures to report.