The first human pathological reports identified cardinal features such as the presence of phosphorylated TDP-43 inclusions (Murray et al., 2011; Boeve et al., 2012; Cooper-Knock et al., 2012; Gijselinck et al., 2012; Solomon et al., 2018) as well as p62 and ubiquitin-positive, but TDP-43–negative, neuronal cytoplasmic inclusions, in human C9ORF72 ALS/FTD tissue (Al-Sarraj et al., 2011; Boxer et al., 2011; Mahoney et al., 2012; Bigio et al., 2013). Here, C9orf72 is linked to amyotrophic lateral sclerosis.