Early infantile epileptic encephalopathies (EIEEs) are severe disorders characterized by drug-resistant seizures and developmental delay. More than 100 genes have been associated with EIEEs, with genetic and phenotypic heterogeneity. Two unrelated patients with EIEE presented with de novo mutations in Neuronal Differentiation Factor 2 (NEUROD2), which had not been previously reported in any human disease. Analysis of patient variants in Xenopus tadpoles revealed a diminished function of the patient alleles, and full loss-of-function mutations resulted in spontaneous seizures during development. Together, this study indicates a requirement of NEUROD2 for proper neural function and implicates NEUROD2 mutations in EIEE. (By Dr. Saquib Lakhani, https://jmg.bmj.com/content/early/2018/10/15/jmedgenet-2018-105322 )