Kostmann syndrome is a rare, severe, congenital neutropenia disorder characterized by a lack of mature neutrophils (absolute neutrophil counts less than 500 cells/mm3) associated with frequent, recurrent bacterial infections (e.g. otitis media, pneumonia, sinusitis, urinary tract infections, abscesses of skin and/or liver) and increased promyelocytes in the bone marrow. Periodontal disease, as well as neurological symptoms, such as cognitive impairment, severe neurodegeneration and epilepsy, have been reported in some patients. The disease is Kostmann syndrome (Monarch Disease Ontology identifier MONDO_0012548). Also known as: infantile agranulocytosis, neutropenia, severe congenital 3, autosomal recessive, severe congenital neutropenia type 3.