ATXN3 and cerebellar ataxia: SCA1 and SCA3 showed very small values of \documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$R^2$$\end{document}R2, except for the relation of cWM and ataxia severity in SCA3.