An intermediate number of CAG repeats were recognized as a risk factor for the clinical manifestation of parkinsonism in SCA2 and SCA3 (van Gaalen et al., 2011; Park et al., 2015; Rossi, Perez‐Lloret, Cerquetti, et al., 2014; Subramony et al., 2002). This evidence concerns the gene ATXN3 and Parkinson disease.