C9orf72 and amyotrophic lateral sclerosis: The main proposed interrupted mechanisms by most genes mutated in ALS include disrupted proteostasis by increased protein aggregation (SOD1, TARDBP, FUS, C9orf72) decreased proteasomal degradation (VCP, UBQLN2), or impaired autophagy (OPTN, TBK1, CYLD, C9orf72, ALS2, SQSTM1, VCP, UBQLN2, CHMP2B).