ATXN10 Gene Expansions in Mexican Patients with Ataxia Without Epilepsy

Spinocerebellar ataxia type 10 (SCA10) is an autosomal dominant (AD) neurodegenerative disorder prevalent in the Americas, particularly in Mexico. Clinical manifestations include progressive ataxia and epilepsy. However, it can exhibit wide phenotypic variability and even reduced penetrance. Because the diagnostic overlaps with other ataxias, molecular diagnosis is essential. This cross-sectional study conducted a retrospective review and analysis of 183 DNA samples from a laboratory registry of patients with ataxia who were suspected of having AD ataxia (n = 86; negative for ATXN1, ATXN2, ATXN3, ATXN7, TBP, and ATN1 genes) or sporadic ataxia (n = 97). Triplet repeat-primed PCR (TP-PCR) was performed to identify ATXN10 gene expansions. 19.6% (n = 36) of the samples showed ATXN10 expansions, with a higher proportion of hereditary AD cases (30.2%; n = 26) compared to sporadic cases (10.3%; n = 10). Clinical information was available in only 23 registries, with manifestations predominantly including cerebellar signs, but notably not epilepsy. The frequency of SCA10 in our country underlines the need to change the diagnostic suspicion, as the absence of epilepsy challenges previous diagnostic assumptions. As this is a study from a laboratory registry, we are aware of certain limitations.