Definition

A bone marrow disorder that can occur in newborns who have Down syndrome. It is marked by abnormal, immature blood-forming cells in the blood and bone marrow (especially the cells involved in making platelets). The liver may also be larger than normal. Transient abnormal myelopoiesis is caused by mutations (changes) in a gene called GATA1. Transient abnormal myelopoiesis usually goes away on its own within the first 3 months of life. Sometimes transient abnormal myelopoiesis causes severe or life-threatening problems, such as bleeding problems, infection, heart, kidney, and liver failure, and abnormal build-up of fluid in the tissues that cover the organs in the body. Infants who have transient abnormal myelopoiesis have an increased risk of developing acute myeloid leukemia (AML) before the age of 3 years. Also called TAM, TMD, transient leukemia, and transient myeloproliferative disorder.