STXBP1 and movement disorder: STXBP1 encephalopathy encompasses a range of neurodevelopmental conditions including autism, intellectual disability (mental retardation), cognitive impairment, and movement disorder (Chai et al, 2016; Lanoue et al, 2019; Saitsu et al, 2010; Stamberger et al, 2016; Tavyev Asher and Scaglia, 2012), and is thought to stem from haploinsufficiency altering the levels of functional STXBP1 protein and gain of toxic function (Lanoue et al, 2019).