ATXN3 and Parkinson disease: In agreement with previous studies (van Gaalen et al., 2011; Park et al., 2015; Rossi, Perez‐Lloret, Cerquetti, et al., 2014; Shan et al., 2001; Subramony et al., 2002), approximately one‐fifth of patients with SCA2 and SCA3 in this study presented with parkinsonism over the course of their disease.