OPTN and amyotrophic lateral sclerosis: Some of the less-frequently mutated genes associated with ALS, of which some are also linked to other neurodegenerative diseases, include OPTN [40], VCP [28,41,42], SQSTM1 [43], FIG4 [44], ATXN2 [45], DAO [46], SPG11 [47], PFN1 [48], VAPB [49], ALS2 [50], SETX [51], and ANG [52].