This group of EE etiologically includes channelopathies (e.g., KCNQ2/3, KCNT1, SCN2A), cell signaling disorders including developmental transcription factor and RNA processing disorders (e.g., FOXG1, GNAO1, BRAT1, CDKL5), synaptopathies and synaptic transmission disorders (STXBP1, DNM1, SPTAN1) and mitochondrial disorders (e.g., PDHA1, PDHB, PDHX, POLG1) (11, 71, 75). The gene discussed is STXBP1; the disease is ethylmalonic encephalopathy.