CSF3 and severe congenital neutropenia: To examine whether SCN patient iPSC–derived granulocytic precursors recapitulate the disease observed in SCN patients, we performed assays of in vitro–directed granulopoiesis in the presence of G-CSF at low (50 ng/mL) and high (1000 ng/mL) concentrations, as described previously (10), which roughly corresponds to peak plasma concentrations of G-CSF in infants receiving 1 or 20 μg/kg/day, respectively (14).