Notch1 is a master regulator of B‐ and T‐cell development.32, 34 While in some types of leukaemia and T‐cell lymphoma the aberrant activation of the Notch1 pathway due to 5’ promoter deletions is associated with atypical myloproliferative disease,36 in human CML cells Notch1 signalling plays a tumour suppressive role, and its overexpression may inhibit tumour proliferation.1, 43 Therefore, targeting Notch1 may represent a therapeutic approach for CML. The gene discussed is NOTCH1; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.