Yet, genetic modifiers of age of onset in C9orf72 patients are largely unknown [only the T-allele of rs1990622 in TMEM106B was associated with a later age of onset of FTD, but not ALS (Gallagher et al., 2014; van Blitterswijk et al., 2014)]. Here, C9orf72 is linked to frontotemporal dementia.