Myelodysplastic Syndrome, Myeloid Leukaemia of Down Syndrome, and Juvenile Myelomonocytic Leukaemia

Myeloid malignancies in children are divided into acute myeloid leukaemia (AML), myelodysplastic syndrome (MDS), juvenile myelomonocytic leukaemia (JMML), and the myeloid leukaemia of Down syndrome (ML-DS). Predisposing genetic conditions are common in MDS. Differentiating MDS from inherited bone marrow failure or AML may be challenging. Therapy consists of observation, immunosuppression, or stem-cell transplantation (SCT). Germline and somatic mutations deregulating the Ras/MAPK signal pathways are key initiating events in JMML. Genetics in JMML defines clinically relevant subgroups and indications for SCT. ML-DS presents with unique clinical characteristics and responds favourably to reduced doses of AML chemotherapy; however, relapse is often refractory to therapy.