STXBP2 and Langerhans cell histiocytosis: A patient with an STXBP2 (c.568C > T, p.Arg190Cys) mutation developed sHLH in the setting of Langerhans cell histiocytosis; NK cell lysis was found to be decreased, improving with sHLH therapies and CD107a expression was significantly lower than controls [30].