SCN8A and encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy: SUDEP was responsible for 36% of the mortality in our STXBP1 cohort, similarly to that observed in other monogenic DEEs, such as SCN8A-DEE (30%) [9], and SCN2A-DEE (33%) [17], but lower than in Dravet syndrome (52%) [17].