VCP and amyotrophic lateral sclerosis: Further familial ALS-associated mutant proteins that are prone to aggregation are valosin containing protein (VCP), dynactin-1 (DCTN1), optineurin (OPTN) and ubiquilin-2 (UBQLN2) (Levy et al., 2006; Maruyama et al., 2010; Deng et al., 2011; Koppers et al., 2012).