C9orf72 and mild neurocognitive disorder: The C9orf72 mutation is a cause of FTD, MND and FTD‐MND23 and while there is consistency that individuals with FTD‐MND phenotype have a short survival, 2–3 years,26 there are increasing reports that there are others who have a range of presentations27 and outcomes, with some people living for a very long time.28