Chromosome translocations involving mixed lineage leukemia (MLL, also known as MLL1 or KMT2A) gene cause ~75% of infant and ~10% child/adult acute leukemias, characterized to be either acute myeloid leukemia (AML) or acute lymphocytic leukemia (ALL) 1-3. The gene discussed is KMT2A; the disease is acute leukemia.