Rare and severe congenital disorder of the bone marrow characterized by thrombocytopenia due to absence or deficient levels of megakaryocytes with no associated birth defects or other blood abnormalities. Caused by mutations in the MPL gene. Typically presents at birth, but may present in the first few weeks of life. Common findings include petechiae, ecchymosis, purpura, and internal bleeding. Prognosis is poor, with 20%-30% of affected patients dying due to hemorrhagic complications.

Treatment includes platelet transfusions. Hematopoietic stem cell transplantation is a curative therapy.