Detection of COL1A1-PDGFB Fusion Transcripts in Dermatofibrosarcoma Protuberans

Background : Dermatofibrosarcoma protuberans (DFSP) is an uncommon infiltrative tumor of the dermis and subcutaneous tissue. Recent cytogenetic studies have demonstrated a chromosomal translocation of the collagen type I alpha 1 (COL1A1) gene on chromosome 17 to 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. Method : The COL1A1-PDGFB fusion transcript was detected by reverse transcriptase-polymerase chain reaction (RT-PCR) using frozen tissue from 4 DFSP patients. Nucleotide sequence analyses were carried out using the PCR products to identify the breakpoints. Results : COL1A1-PDGFB fusion transcripts were detected in all tumor specimens. Sequence analyses revealed that the end of exon 25, 45, 32, or 11 in the COL1A1 gene was fused with the start of exon 2 in the PDGFB gene. Conclusion : Detection of this aberrant fusion transcript can be useful as a diagnostic method for DFSP.