Discordant phenotypes in monozygotic twins with STXBP1 mutation: A case report

Syntaxin-binding protein 1 (STXBP1) is predominantly expressed in the brain and plays an important role in synaptic vesicle docking and fusion [1]. STXBP1 mutations were first reported in patients with Ohtahara syndrome (OS) [2]. Subsequently, various phenotypes of these mutations have been identified, including West syndrome (WS), unclassified early-onset epileptic encephalopathy, and intellectual disability without epilepsy [3].