Finally, there is growing interest in evaluating MRD using more than one marker: in pediatric Ph+ ALL, Hovorkova and colleagues (53) showed that roughly 20% of children have significantly higher BCR/ABL1 levels (assessed by evaluating both genomic DNA and RNA fusion levels) than IG/TR or IKZF1 deletions, indicating that the BCR/ABL1 signal arises from other hemopoietic cells. The gene discussed is ABL1; the disease is acute lymphoblastic leukemia.