PDZD8 and hereditary spastic paraplegia: Protrudin, PDZD8, and Rab7 are all related to neurological disorders, with mutations in the protrudin gene giving rise to the axonopathy HSP (Mannan et al., 2006; Hashimoto et al., 2014), protrudin-deficient mice manifesting psychiatric-like disorders (Shirane et al., 2020a), mutations in the PDZD8 gene being a risk factor for posttraumatic stress disorder (PTSD) (Bharadwaj et al., 2018), and mutations in the Rab7 gene causing another axonopathy, Charcot-Marie-Tooth disease (CMT) (Verhoeven et al., 2003; McCray et al., 2010).