Nonetheless, there is a clear underrepresentation of severe, early‐onset epilepsy phenotypes in our patient cohort relative to those previously published with mutations in STXBP1. This is unlikely to be related to the type of pathogenic variant or its location, as patients in our cohort had a range of stop gain, frameshift, and missense pathogenic variants spread across the protein. This evidence concerns the gene STXBP1 and epilepsy.