ABSTRACTBackground Transient abnormal myelopoiesis (TAM) is characterized by leukocytosis with increased circulating megakaryoblasts that harbor N-terminal truncating mutations in the GATA1 gene. Approximately 10% of affected patients experience early death.Observations A 2-month-old boy with Down syndrome was diagnosed with TAM and followed without treatment. Although the blasts in the peripheral blood disappeared, liver failure progressed. A pathological examination revealed liver fibrosis, and double-immunostaining for full-length GATA1 and CD42b identified megakaryocytes with a GATA1 mutation.Conclusions This simple and cost-effective method can be applied in routine practice to detect TAM blasts during assessment in a TAM crisis.
