<prompt> Which of the following is the most common hematological malignancy in children with Down syndrome?T-cell acute lymphoblastic leukemiaBurkitt leukemiaAcute promyelocytic leukemiaAcute megakaryoblastic leukemia  <response>: Children with trisomy 21 have a high risk of developing leukemia. There is 20-fold increased risk of developing acute B lymphoblastic leukemias. There is 500-fold increased risk of acute myeloid leukemias, most commonly, acute megakaryoblastic leukemia. 