KMT2A and acute myeloid leukemia: Mixed lineage leukemia (MLL) includes acute myeloid leukemia (AML), acute lymphoid leukemia (ALL), and mixed phenotype acute leukemia, occurs in children and adults, accounting for 70 to 80% of infant leukemia cases and 5 to 10% of adult acute leukemia cases and is the most common infant leukemia (1).