The more frequent occurrence of signs of the CBS-MP in c9orf72 compared with GRN pathogenic variant carriers is surprising as previous reports have described CBS to be most often associated with GRN pathogenic variants.28, -, 30 This discrepancy may be due to the fact that most previous studies on motor disorders in genetic FTD have been case reports and case series that have focused on the predominance phenotype without describing accompanying low-grade signs. Here, CBS is linked to frontotemporal dementia.