STUB1 Mutations as Possible Genetic Modifiers in Spinocerebellar Ataxia Type 8

Background Spinocerebellar ataxia type 8 (SCA8) is a dominantly inherited expansion disorder with highly variable penetrance. ATXN8OS/ATXN8 expanded alleles have been identified in association with other types of hereditary ataxias, pointing to a possible genetic synergism. Objectives We aimed to further investigate the molecular background of patients with SCA8 diagnosis. Methods Patients were selected from our cohort of 346 families. A total of 14 probands with SCA8 underwent additional investigation through exome sequencing. Results Pathogenic heterozygous STUB1 variants were found in 21.4% of SCA8 patients (3 of 14) compared to only 0.5% in the non‐SCA8 group (1 of 222), indicating a statistically significant association ( P < 0.05). Conclusions The findings reported in this study might suggest a genetic synergism between STUB1 and ATXN8OS/ATXN8 expanded alleles. Further studies are needed to validate this observation and better define the clinical impact of this genetic interaction.