Spinocerebellar Ataxia Type 23 (SCA23): a rare cause of SCA in the Americas

Spinocerebellar ataxia type 23 (SCA23) is a rare autosomal dominant hereditary ataxia caused by mutation in the PDYN gene. It usually presents in adulthood, with a mean age of onset around 43 years, and progresses slowly with cerebellar symptoms. We report a case of a Brazilian 25-year-old female patient whose symptoms began at 19 years of age, characterized by progressive dysarthria, tremor, dysphagia, and gait disturbance. She had no relatives with similar symptoms. The initial genetic ataxia panel, which included the most prevalent hereditary ataxia genes, was negative. Subsequent next-generation sequencing identified a pathogenic PDYN mutation, confirming the diagnosis of SCA23. Brain MRI demonstrated significant cerebellar atrophy. The patient was referred to a multidisciplinary rehabilitation group with emphasis on functional rehabilitation of gait and dysphagia. This case is notable due to the rarity of this SCA in the Americas, as well for its early onset, given the mean age of SCA23 in the literature, and for the lack of family history of ataxia or any neurological symptoms, suggesting a de novo mutation.