Abstract
Previous studies using whole exome sequencing (WES) have shown that a significant proportion of adult patients with undiagnosed ataxia in European and North American cohorts have a known genetic cause. Little is known about the diagnostic yield of WES in non-Caucasian ataxic populations. Herein, we used WES to investigate a Brazilian cohort of 76 adult patients with idiopathic ataxia previously screened for trinucleotide expansions in known ataxia genes. We collected clinical and radiological data from each patient. WES was performed following standard procedures. Only variants labeled as pathogenic or likely pathogenic according to American college of medical genetics and genomics (ACMG) criteria were retrieved. We determined the diagnostic yield of WES for the whole cohort and also for subgroups defined according to presence or not of pyramidal signs, peripheral neuropathy, and cerebellar atrophy. There were 41 women and 35 men. Mean age at testing was 48 years. Pyramidal signs, peripheral neuropathy, tremor, and cerebellar atrophy were found in 38.1%, 13.1%, 10.5%, and 68.3% of all subjects, respectively. Diagnostic yield of WES was 35.5%. Thirty-six distinct mutations were found in 20 different genes, determining the diagnosis of 18 autosomal recessive and 9 autosomal dominant ataxias. SACS and SPG7 were the most frequently found underlying genes. WES performed better in the subgroup with vs the subgroup without spasticity (p = 0.005). WES was diagnostic in 35.5% of cases of the Brazilian cohort of ataxia cases. These results have implications for diagnosis, genetic counseling and eventually treatment.
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This work was supported by Fundação de Amaro à Pesquisa do Estado de São Paulo (FAPESP) Grant # 2013/07559–3.
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All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by all authors. The first draft of the manuscript was written by Felipe Franco da Graça and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.
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da Graça, F.F., Peluzzo, T.M., Bonadia, L.C. et al. Diagnostic Yield of Whole Exome Sequencing for Adults with Ataxia: a Brazilian Perspective. Cerebellum 21, 49–54 (2022). https://doi.org/10.1007/s12311-021-01268-1
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DOI: https://doi.org/10.1007/s12311-021-01268-1