C9orf72 and Mental deterioration: The presence of a pathogenic (disease-causing) variant in any of the three most common genes associated with autosomal dominant FTD (MAPT, GRN, C9orf72) is associated with reduced survival.7 More rapid cognitive decline is also associated with the presence of a C9orf72 expansion.8 Moreover, several common genetic variants, including single-nucleotide polymorphisms, have been associated with reduced survival9 and more rapid cognitive decline.10,11