Myeloid leukemia associated with Down syndrome

The World Health Organization places this leukemia within myeloid proliferations associated with Down syndrome, a category that also includes transient abnormal myelopoiesis. It arises in children with Down syndrome, typically between about 1 and 4 years of age, and is commonly, though not invariably, megakaryoblastic. Transient abnormal myelopoiesis is confined to the first 6 months of life, and about one in five affected infants later develops this leukemia.