BCR and acute lymphoblastic leukemia: Chromosomal rearrangements (e.g., MLL rearrangements (MLL-r) in acute myelogenous leukemia (AML) or BCR–ABL1 in chronic myelogenous leukemia (CML)) and mutations (point mutations in EZH2 in acute lymphocytic leukemia (ALL)) can affect chromatin state [19,20,21,22,23] and/or activity of the enzymes involved in methylation/demethylation or acetylation/deacetylation of chromatin.