Severe congenital neutropenia: One of several genetic disorders of the bone marrow that is evident at birth and characterized by a lack of neutrophils (a type of white blood cells that are important in fighting infection). Children with severe congenital neutropenia suffer from frequent bacterial (but not viral or fungal) infections. They are also at increased risk for acute myelogenous leukemia (AML) and myelodysplasia. Autosomal dominant and sporadic forms of severe congenital neutropenia are most frequently caused by mutation in the neutrophil elastase gene (ELA2) on chromosome 19. There is an X-linked recessive form of severe congenital neutropenia in males that is caused by mutation in the WAS gene (which is also mutated in Wiskott-Aldrich syndrome). Kostmann disease is a form of severe congenital neutropenia that is inherited in an autosomal recessive manner. Treatment of severe congenital neutropenia involves use of recombinant human granulocyte colony'stimulating factor (GCSF). GCSF elevates the neutrophil count, helps resolve preexisting infections, diminishes the number of new infections, and results in significant improvements in survival and quality of life. Patients treated with GCSF may nonetheless develop leukemia or myelodysplastic syndrome. Also known as infantile genetic agranulocytosis.