KMT2A and acute lymphoblastic leukemia: As regards acquired genetic differences, although single nucleotide polymorphism (SNP) analyses have in general identified similar microdeletions in DS-ALL and non-DS-ALL cases [16,22-25], DS-ALL and non-DS-ALL are to a large extent cytogenetically distinct – DS-ALL are rarely high hyperdiploid (51–67 chromosomes) and seldom display MLL rearrangements or t(9;22)(q34;q11)/BCR-ABL1[5,20,26,27].