OPTN and amyotrophic lateral sclerosis: ALS-associated mutations in TBK1 and the functionally related protein OPTN have clearly established roles in mitophagy with OPTN recognizing damaged mitochondria through its ubiquitin-binding domain, and TBK1 phosphorylating OPTN and increasing the ubiquitin-binding ability of OPTN (Wong and Holzbaur, 2014a; Moore and Holzbaur, 2016; Bader and Winklhofer, 2020; Evans and Holzbaur, 2020b; Montava-Garriga and Ganley, 2020; Wang L. et al., 2020).