STXBP1 and epilepsy: Since then, mutations in STXBP1 have been described in different patient cohorts, the phenotypic spectrum of patients with STXBP1 mutations has expanded, and an increasing number of studies have indicated that epilepsy and intellectual disease (ID) are 2 major features of STXBP1 encephalopathy (STXBP1-E) (7, 8).