BCR and B-cell chronic lymphocytic leukemia: Modern classifications, such as the International Consensus Classification (ICC), refine the distinction between main leukemia types—acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), chronic lymphocytic leukemia (CLL), and chronic myeloid leukemia (CML)—which are uniquely linked to the Philadelphia chromosome (BCR::ABL1 fusion gene) [51,52,53,54].