C9orf72 and frontotemporal dementia: While ALS and FTD are the major phenotypes linked to C9orf72 repeat expansions, several additional phenotypes are documented, including Alzheimer's disease, Parkinson’s disease, Huntington’s disease-like movement disorder and various psychiatric presentations.13 14 Inclusion of such phenotypes adds complexity to pedigree interpretations on account of the high population prevalence of some of these conditions.