PTPN23 mutations were recently linked to developmental epileptic encephalopathy with hypomyelination, brain atrophy and developmental delay (Alazami et al., 2015; Sowada et al., 2017; Smigiel et al., 2018), indicating that functional PTPN23 is also essential for the development of the human nervous system. The gene discussed is PTPN23; the disease is Brain atrophy.