A novel fusion gene of collagen type I alpha 1 (exon 31) and platelet-derived growth factor B-chain (exon 2) in dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is an uncommon, slow growing, sarcoma of dermal and subcutaneous tissue with an infiltrative growth pattern. Although DFSP has a high rate of local recurrence, it rarely metastasizes. DFSP is characterized by a chromosomal translocation involving the collagen type 1 a 1 (COL1A1) gene on chromosome 17 and the platelet-derived growth factor B-chain (PDGFB) gene on chromosome 22. Various exons of the COL1A1 gene have been reported to be involved in the fusion with exon 2 of the PDGFB gene. In this study, we examined the COL1A1-PDGFB fusion transcripts using frozen specimens from three patients with DFSP. The molecular biology study with reverse transcriptase polymerase chain reaction (RT- PCR) and sequencing showed that the ends of exons 25, 31, and 45 in the COL1A1 gene were fused with PDGFB. The exon 2 of the PDGFB gene fused with exon 31 of the COL1A1 gene was a novel fusion gene.