Pediatric acute myeloid leukemias are disease with poor prognosis (overall survival of 60-75%) and high relapse rate of 35-45% require further understanding of the underlying biological mechanisms. The main objective of this study is to establish a biological collection to evaluate the genomic profiling of leukemic cells from primary blasts at diagnosis and/or relapse to improve identification of the main genetic hits involved in resistance and could predict a high risk of relapse. Other objectives include the study of bone marrow mesenchymal stem cells and ex vivo drug testing.