In RUNX1 intron 5 (24.8 kb), three smaller regions were identified as the chromosomal breakpoints involved in the translocation in AML patients and were named breakpoint cluster regions (BCRs): BCR1 (0.8 kb), BCR2 (4.2 kb), and BCR3 (2.1 kb) [9]. This evidence concerns the gene RUNX1 and acute myeloid leukemia.