DDIT3 and Pelizeaus-Merzbacher spectrum disorder: Further, CHOP deficiency accentuates the phenotype of Pelizaeus-Merzbacher Disease mice [38] yet rescues the motor deficits of Charcot-Marie-Tooth 1B mice [39], demonstrating that deletion of this transcription factor is an informative approach to probing the role of the UPR in model systems.