In contrast to SCA3, and as with HD, this study also revealed clear allele length effects on somatic dynamics of the expanded ATXN1 CAG in SCA1, the expanded ATXN2 repeat in SCA2, and the expanded ATXN7 CAG repeat in SCA7 (Kacher et al. 2024). The gene discussed is ATXN2; the disease is Huntington disease.