In the last years, Prof. Klusmann has made major contributions towards understanding the pathogenesis of acute myeloid leukemia in children with Down syndrome, and towards improving their treatment options. In parallel, he has described miR-125b, an oncogene on chromosome 21 which helps explain the 20-fold higher frequency of AML in infants with Down syndrome. This work introduced microRNAs as a new class of genes that involved in Down syndrome leukemogenesis, and was awarded the “Leukemia Clinical Research Awards 2011” of the German Society of Hematology and Oncology (DGHO) and the “Rudolf Schoen-Prize 2011” of the TUI foundation for outstanding scientific and clinical achievements.