OPTN and amyotrophic lateral sclerosis: An increasing number of perturbations in OPTN gene function have been linked to diseases including primary open-angle glaucoma (POAG), amyotrophic lateral sclerosis (ALS), Paget's disease of bone (PDB) and Crohn's disease (CD) (Albagha et al., 2010; Maruyama et al., 2010; Rezaie et al., 2002; Smith et al., 2015).