It is treated primarily with tyrosine kinase inhibitors (TKIs), which target the Breakpoint Cluster Region-Abelson Tyrosine Kinase 1 (BCR::ABL1) fusion protein.[1] Dasatinib, a second-generation TKI, inhibits multiple tyrosine kinases including BCR::ABL1, and is a common treatment choice for CML.[2] Possible adverse effects of dasatinib include pulmonary hypertension[3] and pericardial effusion,[4] although these are relatively uncommon. The gene discussed is ABL1; the disease is pulmonary arterial hypertension.