Besides the strong link to ALS and FTD, which are both heterogeneous diseases, the phenotypic spectrum of C9orf72 expansions extends to other neurodegenerative syndromes such as PD, progressive muscular atrophy (PMA), primary lateral sclerosis (PLS), Huntington-like disease as well as ataxia syndromes [51–54]. The gene discussed is C9orf72; the disease is frontotemporal dementia.