After applying adenosine deaminase inhibitor 1 week after lineage switch, 60% of the bone marrow blast cells were strongly MPO positive, according to the transformation and amplitude of leukemia cells insensitive to the original treatment.17 A study of ALL antigen receptor gene rearrangement PCR in 27 patients showed 13 relapses as an obvious new clonal subtype (not detected by conventional testing). The gene discussed is MPO; the disease is acute lymphoblastic leukemia.