Acute myeloid leukemia with an fusion in a young child with Down syndrome.

Myeloid leukemia of Down syndrome (ML-DS) in young children is associated with distinct clinical and biological features and is typically initiated with oncogenic mutations in the X-linked megakaryocytic transcription factor Here we present a 3-yr-old child with DS diagnosed with acute myeloid leukemia (AML), which lacks typical immunophenotypic and molecular characteristics of ML-DS, including mutations. The leukemic blasts were found to have an gene fusion, a high-risk oncofusion not previously described in DS patients. This report highlights the importance of immunophenotypic, cytogenetic, and molecular characterization of ML-DS for identification of rare cases with unique features that may benefit from treatment protocols that are more intensive than those developed for patients with typical mutant ML-DS.