ATXN7 and juvenile Huntington disease: It is believable that de novo mutations of ATXN3 exist since they have been found in some other dynamic mutation diseases such as Huntington’s disease (HD; MIM# 143100) [38], SCA2 (MIM# 183090) [39], SCA7 (MIM# 164500) [40] and SCA17 (MIM# 607136) [41].