A novel fusion gene involving PDGFRB and GCC2 in a chronic eosinophilic leukemia patient harboring t(2;5)(q37;q31)

Background Platelet‐derived growth factor receptor beta (PDGFRB) rearrangement has been reported in a number of patients with chronic eosinophilic leukemia (CEL), B‐acute lymphoblastic leukemia, myeloproliferative neoplasms, and juvenile myelomonocytic leukemia. Here, we report a case of CEL carrying a novel fusion gene involving PDGFRB and GRIP and coiled‐coil domain containing 2 (GCC2). Patient and methods A 54‐year‐old man presenting with a cough and dyspnea was diagnosed with acute eosinophilic pneumonia. Cytogenetic analysis of the bone marrow revealed the presence of t(2;5)(q37;q31). Fluorescence in situ hybridization analysis in the peripheral blood leukocytes revealed the presence of a split signal at PDGFRB gene. Imatinib treatment was effective, and disappearance of t(2;5)(q37;q31) in the bone marrow was confirmed after three months of imatinib therapy. Whole‐genome sequencing was performed in peripheral blood leukocytes collected before imatinib therapy. Results A novel fusion gene between exon 22 of GCC2 and exon 12 of PDGFRB was detected and the presence of GCC2‐PDGFRB was confirmed by PCR. Conclusion This is the first case report demonstrating the GCC2 gene as a partner of PDGFRB in the pathogenesis of CEL. Whole genome sequence identifying the breakpoint forming platelet‐derived growth factor receptor beta (PDGFRB) and GRIP And Coiled‐Coil Domain Containing 2 (GCC2) fusion gene (a). Direct sequencing analysis confirming the presence of GCC2‐PDGFRB fusion gene (b).