Detection of t(4;14)(p16.3;q32) chromosomal translocation in multiple myeloma by reverse transcription-polymerase chain reaction analysis of IGH-MMSET fusion transcripts.

We and others have recently identified a novel recurring t(4;14)(p16.3; q32) translocation in multiple myeloma (MM) that leads to an apparent deregulation of the FGFR3 and WHSC1/MMSET genes. Because the presence of IGH-MMSET hybrid transcripts has been found in MM cell lines with t(4;14), they may represent a specific tumor-associated marker in MM. In this study, we developed a reverse transcription-PCR (RTPCR) assay for detecting chimeric transcripts from all of the 4p16.3 breakpoints identified thus far, and we used it to investigate a representative panel of 53 MM patients and 16 patients with monoclonal gammopathy of uncertain significance; in addition, t(4;14) was investigated in all of the MM patients by means of two-color fluorescence in situ hybridization. IGH-MMSET transcripts were found in 11 of the 53 (20%) MM cases and 1 of 16 (6%) cases of monoclonal gammopathy of uncertain significance. There was complete concordance between the RT-PCR and fluorescence in situ hybridization analyses of the MM cases. The results of this study indicate that RT-PCR is a sensitive and reliable method of detecting t(4;14) and suggest that it may be useful for monitoring the disease in a significant proportion of patients.