RFC1 and Parkinson disease: This study found that three patients with PD (1.5%) had heterozygous mutations in ATXN8OS and that one patient with PD (0.5%) had compound heterozygous mutations in RFC1. In contrast, no patient had a mutation in C9ORF72, NOTCH2NLC, BEAN1/TK2, or NOP56, some of which have been mutated in PD in other countries (18, 33).