Platelet derived growth factor receptor alpha (PDGFRA) is a part of a family of proteins called receptor tyrosine kinases. FIP1L1-PDGFRA is a novel oncogenic mutation which is associated with a primary eosinophilic disorder. It is seen in Chronic eosinophilic leukemia and Systemic mast cell disease associated with eosinophilia. Patients with this mutation respond well to Imatinib therapy. Activating mutations in PDGFRA are also involved in 2-15% cases of Gastrointestinal stromal tumors (GIST).