ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: While the single-target focus holds many practical efficiencies, it is clearly of greater relevance to the ‘one gene–one disease’ theory, including both inherited diseases (e.g., the delta508Phe deletion in CFTR associated with cystic fibrosis) [22] and certain cancer driver mutations (e.g., BCR-ABL in chronic myeloid leukemia (CML)) [23].