Molecular Biology of Childhood Leukemia

Childhood hematological malignancies (HM) exhibit profound genetic and biological heterogeneity. Many sporadic and familial HM have a heritable predisposition. Genomic sequencing has revised the taxonomy of lymphoid and myeloid leukemias, indicating the importance of accurate molecular diagnosis in disease management. Notable examples include the identification of gene expression–based subtypes of acute lymphoblastic leukemia (ALL), identification of diverse rearrangements of NUP98 in high-risk acute myeloid leukemia (AML), characterization of the interplay of cell-of-origin and genomic alterations in lineage-ambiguous leukemias, and the prognostic importance of DNA methylation in juvenile myelomonocytic leukemias. These insights provide therapeutic opportunities, including kinase inhibition in Ph-like ALL, menin inhibition in KMT2A-rearranged AML, histone deacetylase inhibition in MEF2D-rearranged ALL, and FLT3 inhibition in T-lineage and myeloid leukemias. We provide an overview of the molecular foundation and classification of childhood leukemias, focusing on recent scientific advances, and discuss potential therapeutic implications.