ATXN3 and Huntington disease: SCA7 is caused by the expansion of a CAG repeat encoding a polyglutamine (polyQ) tract in ATAXIN-7 (ATXN7) [2, 3], and hence belongs to the family of 9 polyQ neurodegenerative disorders, which include 5 other SCAs (SCA1, SCA2, SCA3, SCA6 and SCA17) and Huntington’s disease (HD).