Interestingly, five of the mutations in UBQLN2 that cause ALS are located in or near a highly unusual PXX repeat domain that is not present in other ubiquilins (Deng et al., 2011b; Williams et al., 2012), and two additional mutations are located at the N-terminus (Daoud et al., 2012). Here, UBQLN2 is linked to amyotrophic lateral sclerosis.