BCR‐ABL is a protein that results from the chromosomal translocation of the ABL gene from chromosome 9 to the BCR gene on chromosome 22, t(9;22), originating the so‐called Philadelphia chromosome (Ph), present in most cases of CML (>95%), and in some cases of ALL (ALL‐Ph+).65, 66, 67. The gene discussed is BCR; the disease is acute lymphoblastic leukemia.