Our objective was to characterize a group of adult and pediatric patients with ataxia and to evaluate the yield of our own clinical-molecular algorithm, by the use of classical and new generation sequencing techniques.

An exploratory, prospective, observational and descriptive study was carried out in 268 patients with progressive ataxia evaluated between May 2008 and May 2018. Patients were stratified in autosomal dominant, recessive and sporadic inheritance ataxias and we used the clinical-molecular algorithm proposed in each subject. Molecular studies included individual gene sequencing, trinucleotide expansion characterization, new generation multigene sequencing and whole exome and genome sequencing.

Through the use of our clinical-molecular algorithm, we identified the causative gene in 95 subjects, obtaining a diagnosis yield of 31%, the diagnosis yield increases if we consider only subjects with positive family history (57%),particully in the subgroup of recessive ataxias (71%). Spinocerebellar ataxia type-2 (35%) and Friedreich ataxia (65%) were the most frequent dominant and recessive ataxias respectively. The use of massively parallel sequencing methods were of diagnostic utility in 53% of cases where this techniques were used.

We developed and implemented locally a clinical-molecular algorithm that allowed us obtaining a genetic diagnosis in a significant number of patients. Our study describes the most important series of hereditary ataxia patients to date and provides relevant epidemiological information for a better and precise knowledge of the most prevalent subtypes of genetic ataxias in our country.