ATXN7 and Huntington disease: Consistently, germline transmission studies in SCA3 have also failed to reveal obvious parental allele length effects (Maciel et al. 1995; Durr et al. 1996; Martins et al. 2008; Souza et al. 2016) that are characteristic of SCA1, SCA2, SCA7, HD and most other repeat expansion disorders (Depienne and Mandel 2021).