Response of congenital neutropenia patients with G-CSF receptor mutations to r-metHuG-CSF treatment. ANC of patients FR, MA, BP, and PB undergoing treatment with r-metHuG-CSF are depicted. The patients received a daily dose of 1 μg/kg/d (FR and BP), 3 μg/kg/d (PB), and 20 μg/kg/d (MA). In patient BP, the dose was increased up to 10 μg per day in March 1996 (#) to mobilize progenitor cells into the peripheral blood before leukaphoresis. Bone marrow mononuclear cells from patient BP taken before the start of G-CSF treatment in 1987 showed no G-CSF receptor mutation. In patient FR, G-CSF therapy was interrupted when monosomy 7 was diagnosed as indicated by the bar (-). Sequencing of the G-CSF receptor at different time points demonstrated either a normal (%) or a mutated (*) G-CSF receptor.