ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: A recent study, while assessing minimal residual disease in children with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+-ALL), found that, in some patients, from 12 to 83% of nonmalignant B cells, T cells, and myeloid cells were positive for BCR-ABL1, suggesting that the translocation probably have occurred in a multipotent hematopoietic cell, thus concluding that these patients were actually affected by CML in blast crisis rather than de-novo Ph+-ALL (24).