C9orf72 and frontotemporal dementia: RNA foci of the C9ORF72 repeat expansion were initially observed in the spinal cord of ALS/FTD patients (DeJesus-Hernandez et al., 2011; Renton et al., 2011), although the RNA level of C9ORF72 is decreased in patients with ALS and the C9ORF72 repeat expansion (Renton et al., 2011).