The percentage of patients positive for C9orf72 repeat expansion (defined as presence of >30 repeats) was 10.4% in patients with FTD (5 out of 48 patients tested), 10.7% in patients with ALS (6/56) and 27.3% in patients with FTD-ALS (3/11). Here, C9orf72 is linked to frontotemporal dementia.