 The FIP1L1-PDGFRA fusion gene is a recurrent molecular lesion in eosinophilia-associated myeloproliferative disorders, predicting a favorable response to imatinib mesylate.     ///    The FIP1L1-PDGFRA fusion transcript was detected at a sensitivity of 1 in 10(5) in serial dilution of the EOL-1 cell line.     ///    "Overall, 11 of 11 evaluable patients achieved at least a 3-log reduction in FIP1L1-PDGFRA fusion transcripts relative to the pretreatment level within 12 months, with achievement of molecular remission in 9 of 11 (assay sensitivities 1 in 10(3)-10(5)). "    ///    "In 2 patients, withdrawal of imatinib was followed by a rapid rise in FIP1L1-PDGFRA transcript levels. "    ///    Normalized FIP1L1-PDGFRA transcript levels in patient samples prior to imatinib varied by almost 3 logs.     ///    Serial monitoring was undertaken in patients with a high level of FIP1L1-PDGFRA expression prior to initiation of imatinib (100 mg/d-400 mg/d). 