STXBP1 and infantile spasms: This study was followed by a number of studies identifying numerous Munc18-1 mutations in patients suffering from not only early onset epileptic encephalopathies such as West syndrome, Lennox-Gastaut syndrome, and Dravet syndrome, but also in patients that present without an epileptic phenotype and are diagnosed with atypical Rett syndrome, intellectual disability without epilepsy, ataxia-tremor-retardation syndrome without epilepsy.