title: Detection of myxoid liposarcoma-associated FUS-DDIT3 rearrangement variants including a newly identified breakpoint using an optimized RT-PCR assay.
abstract: Myxoid/round cell liposarcoma is characterized by the recurrent translocations t(12;16)(q13;p11) and, less commonly, t(12;22)(q13;q12), which fuse FUS or EWSR1, respectively, to DDIT3 on chromosome 12. Although a number of different variant breakpoints have been described, greater than 90% of all cases have one of the three different FUS-DDIT3 fusions, which may have clinical significance. To identify the individual breakpoints, a sequence-specific assay such as reverse transcription-PCR (RT-PCR) is needed. In this study, we optimized primer design to develop an RT-PCR assay for the detection of the most common translocations in formalin-fixed paraffin-embedded tissue specimens. We compared our assay with primers previously published for testing formalin-fixed paraffin-embedded specimens and achieved the most consistent results with our primers. We obtained RNA from 32 MLS cases, of which 27 carried one of the three common FUS-DDIT3 chimeric transcript types. Four of the negative cases were from very small biopsies with very low RNA concentration. One case was consistently negative by RT-PCR, but showed a FUS rearrangement by fluorescent in situ hybridization, suggesting that it may harbor one of the rarer FUS-DDIT3 chimeric types. In addition to the common fusions, our assay also identified a novel FUS-DDIT3 fusion between exon 9 of FUS and exon 3 of DDIT3 in one of the cases.
authors.affiliation: Division of Molecular Pathology, Department of Pathology, Baylor College of Medicine and Texas Children's Hospital, Houston, TX 77030, USA.
authors.forename: Martin P
authors.initials: MP
authors.lastname: Powers
authors.forename: Wei-Lien
authors.initials: WL
authors.lastname: Wang
authors.forename: Vivian S
authors.initials: VS
authors.lastname: Hernandez
authors.forename: Kayuri S
authors.initials: KS
authors.lastname: Patel
authors.forename: Dina C
authors.initials: DC
authors.lastname: Lev
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Lazar
authors.forename: Dolores H
authors.initials: DH
authors.lastname: López-Terrada
mesh_terms: D056905:Chromosome Breakpoints; D017931:DNA Primers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D018208:Liposarcoma, Myxoid / Q000235:genetics*; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods*; D014178:Translocation, Genetic
chemical_list: D017931:DNA Primers; C532377:FUS-DDIT3 fusion protein, human; D015514:Oncogene Proteins, Fusion