EIMFS is a severe, drug-resistant, early-onset epilepsy encephalopathy in which variants in the KCNT1, SCN1A, SCN8A, SCN2A, PLCB1, KCNT1, SLC25A22, TBC1D24 and SLC12A5 genes as well as 16p11.2 duplication have been reported. This evidence concerns the gene SLC25A22 and epilepsy of infancy with migrating focal seizures.