ATF4 and glaucoma: While multiple genes, proteins, and transcription factors have been identified that are associated with axon death [e.g. BAX (BCL2-associated X protein), TRX (thioredoxin), HIF-1α (hypoxia-inducible factor-1α), SNCG (γ-synuclein), ATF4 (activating transcription factor 4), DDIT3 (DNA damage inducible transcript 3), and BCAT1 (branched chain amino acid transaminase 1) (Libby et al., 2005a; Soto et al., 2008; Munemasa and Kitaoka, 2013; Yasuda et al., 2014; Cheng et al., 2017), the causative genes and variants remain unknown for the majority of glaucoma cases.