C9orf72 and frontotemporal dementia: However, prominent atrophy of the thalamus also occurs in both sporadic and familial forms of FTD (Bocchetta et al., 2018), including FTD because of C9orf72 HRE (hereafter referred to as C9-FTD) as well as pathogenic variation in MAPT, GRN, and other FTD-associated genes.