C9orf72 and Parkinson disease: Stratifying by individual genetic group, 7.7% of C9orf72 mutation carriers had a motor diagnosis, all with ALS/FTD-ALS, in comparison with 1.4% of GRN mutation carriers, 0.5% with PSP, 0.5% with CBS and 0.5% with a diagnosis of PD, and 2.3% of MAPT mutation carriers, 1.1% with PSP and 1.1% with CBS.