A Neonate with Down’s Syndrome and Transient Abnormal Myelopoiesis: Serial Blood and Bone Marrow Studies

Observations were made of the blood and bone marrow of a male infant with Down’s syndrome during the first year of life. At 4 days of age there were 36,500 myeloblasts/cu.mm. in the blood and 10.8 per cent myeloblasts in the marrow. Initially it appeared the patient had acute myeloblastic leukemia. However, the clinical course and kinetic and electron microscopic studies of his bone marrow cell population indicate he did not have acute leukemia.