In hematological disorders, most recurrent gene fusions are studied, such as BCR-ABL1 in chronic myeloid leukemia (CML)3, PML-RARA in acute promyelocytic leukemia (APL)4, RUNX1-RUNX1T1 in acute myeloid leukemia (AML)5 and SIL-TAL1 in pediatric T-cell acute lymphoblastic leukemia (T-ALL)6. The gene discussed is BCR; the disease is acute promyelocytic leukemia.