TCF4 and early-infantile DEE: We identified four mutations in genes such as HCN129 and GRIN2B30, which are associated with early infantile epileptic encephalopathy; SLC6A1, which is associated with epilepsy and myoclonic-atonic seizures31; TCF4, which is associated with Pitt–Hopkins syndrome21; and SCN1A, which is associated with Dravet syndrome32.