Imatinib, a tyrosine kinase inhibitor (TKI) that targets ABL, BCR-ABL, PDGFRA, and c-KIT, is widely used in treating chronic myelogenous leukemia (CML) and gastrointestinal stromal tumors (GIST). The gene discussed is PDGFRA; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.