Around 30% of FTD is familial, most commonly caused by autosomal dominant genetic mutations in one of three genes: progranulin (GRN), microtubule-associated protein tau (MAPT) or chromosome 9 open reading frame 72 (C9orf72) (Rohrer et al., 2009). The gene discussed is C9orf72; the disease is frontotemporal dementia.