BCR and acute lymphoblastic leukemia: Among them, there are the old classifications BCR-ABL1 +ALL (Ph+), BCR-ABL1-like B-ALL (Ph-like or Ph-), and the KMT2A rearrangement, also known as MLL (mixed-lineage or myeloid-lymphoid leukemia), consisting of the rearrangement of the lysine methyltransferase 2A encoding gene to a highly diverse range of partner genes [21].