C9orf72 and amyotrophic lateral sclerosis: With the advent of whole-exome sequencing, there has been a tremendous increase in discovery of new disease-causing genes in ALS, notably fused in sarcoma (FUS), TAR DNA-binding protein 43 (TDP-43), C9orf72, optineurin (OPTN), sequestosome 1 (SQSTM1), ubiquilin 2 (UBQLN2), dynactin (DCTN1), MATR3 and valosin-containing protein (VCP; Renton et al., 2014).