congenital agranulocytosis
Kostmann syndrome
A haematopoietic disorder (OMIM:610738) characterised by maturational arrest of granulopoiesis at the promyelocyte stage, resulting in an absolute neutrophil count below 0.5 x 109/l and early severe bacterial infections (neutrophil-limited disease occurs in patients with mutations of HAX1 isoform 1). Some patients also have neurological manifestations (e.g., psychomotor retardation and seizures), which result from mutations of HAX1 isoforms 1 and 5.Management
Filgrastim, a granulocyte colony-stimulating factor analog, improves neutrophil counts and immune function. While it is the mainstay of therapy, its use is linked to an increased risk of myelofibrosis and acute myeloid leukaemia.
Molecular pathology
Defects of HAX1, which encodes a protein that promotes cell survival, cause Kostmann syndrome.