STXBP1 and epilepsy: Heterozygous pathogenic variants in syntaxin‐binding protein 1 (STXBP1, previously called Munc18‐1), encoded by the STXBP1 gene, have been reported in nearly 200 patients with various types of developmental disorders, primarily epilepsy/epileptic encephalopathy, developmental delay, and intellectual disability (Saitsu et al.