The COL1A1-PDGFB fusion gene is detectable either by multiplex RT-PCR with a combination of forward primers designed from a variety of COL1A1 exons and one reverse primer for PDGFB exon 2, or by in situ fluorescence hybridization (FISH) on interphase nuclei from frozen or fixed paraffin-embbeded sections.     ///    These chromosomal rearrangements lead to the formation of a specific fusion gene : COL1A1-PDGFB detected in rings as well as in translocations.     ///    "So far, the COL1A1-PDGFB fusion gene remains the only fusion gene identified in this tumor. "    ///    "The COL1A1-PDGFB fusion gene is not found in approximately 8% of DP cases, suggesting that genes other than COL1A1 or PDGFB might be involved in a small subset of cases. "