SCN1A and Global developmental delay: Another recent scoping review of studies in infants with DEE identified STXBP1, SLC1A2, CDKL5, SCN1A, and KCNT1 as frequently mutated genes; each was associated with distinctive electroclinical features (age at seizure onset, seizure type, EEG pattern, degree of developmental delay) though with substantial inter-individual variation [5].