C9orf72 and amyotrophic lateral sclerosis: This C9orf72 NRE mutation is a hexanucleotide repeat, GGGGCCn (G4C2)n, and is currently the most prevalent genetic association for amyotrophic lateral sclerosis (ALS) and frontal temporal dementia (FTD) (Majounie et al, 2012b; Rademakers, 2012).