Mutations in the gene involved in the UPS pathway have been reported in neurodegenerative diseases, such as Parkin, an E3 ligase, in Parkinson’s disease and UBQLN2, a ubiquitin-like protein, in dominant X-linked juvenile and adult onset amyotrophic lateral sclerosis [29,30]. Here, UBQLN2 is linked to amyotrophic lateral sclerosis.