C9orf72 and frontotemporal dementia: This is well in line with other ALS and ALS–FTD imaging studies where cohorts who tested negative for C9orf72 hexanucleotide repeat also demonstrate marked cortical, suborbital, and white matter pathology (McKenna, Tahedl, et al., 2021; Omer et al., 2017; Westeneng et al., 2016).