Objective: To detect the IgH-MMSET fusion gene resulted from t (4;14) translocation in multiple myeloma and illuminate its significance.
Methods: IgH-MMSET fusion gene was detected in bone marrow specimens of 25 multiple myeloma (MM) patients and MM cell line NCI-H929 using reverse-transcription PCR (RT-PCR) assay followed by nested PCR to increase the sensitivity. The purified PCR products were cloned into pGEM-T vector and then sequenced using M13 forward primers. The fragment sequences were compared with that in GenBank to find matched sequences.
Results: Only a 438 base pair long fragment was obtained after RT-PCR assay and was confirmed by sequencing to be a fusion gene product of IgH gene and MMSET gene in MM cell line NCI-H929. The breakpoints were located within the C micro region of IgH gene on chromosome 14 and intron 3 of MMSET gene on chromosome 4. IgH-MMSET hybrid transcripts were detected in 3 of 25 MM patients through nested PCR assay. The amplified fragments of the 3 patients were 237 base pairs (bp), 239 bp and 239 bp in length, respectively. The breakpoints on chromosome 4 were identical to that of NCI-H929 cell.
Conclusions: The formation of IgH-MMSET fusion gene is resulted from t (4;14) translocation in MM. The incidence rate is 12.0%. The presence of IgH-MMSET fusion gene may predict poor prognosis.