ATXN10 encodes ataxin-10, a protein primarily involved in regulating cytokinesis and neuronal development 12. The protein localizes to perinuclear cytoplasmic regions, the midbody, and dendrites, where it functions in neuritogenesis by activating the Ras-MAP kinase pathway and supporting cerebellar neuron survival [UniProt]. ATXN10 also binds ataxia-associated proteins and localizes to stress granules, potentially modulating protein glycosylation and cellular signaling 3. Pathogenic ATTCT pentanucleotide repeat expansions in ATXN10 intron 9 cause spinocerebellar ataxia type 10 (SCA10), an autosomal dominant neurodegenerative disorder 45. SCA10 presents with progressive cerebellar ataxia, with variable phenotypes including epilepsy, particularly in Mexican and some Brazilian populations, though epilepsy-free presentations occur in other regions 65. Notably, uninterrupted repeat expansions (ATTCTint+) associate with earlier disease onset, higher seizure frequency, and worse clinical severity compared to interrupted repeats (ATTCTint-) 7. While ATXN10 expansions account for significant hereditary cerebellar ataxia cases in the Americas, standard whole-genome sequencing struggles with accurate repeat sizing 8.