Validation of a new three-color fluorescence in situ hybridization (FISH) method to detect CHIC2 deletion, FIP1L1/PDGFRA fusion and PDGFRA translocations.

The PDGRFA locus has become a gene of interest based on mutational activation in various myeloid neoplasms and the availability of targeted therapies (i.e., imatinib mesylate) to its overexpression. We studied a new FISH method to detect CHIC2 deletion, FIP1L1/PDGFRA fusion and PDGFRA translocation in patients with myeloid neoplasms associated with eosinophilia. A total of 46 specimens were studied, including 15 from patients with a CHIC2 abnormality and six patients with an abnormality involving PDGFRA. Our results revealed this new FISH assay accurately detects these abnormalities and will be a useful clinical test for patients with myeloid neoplasms and eosinophilia.