The IGH/CCND3 product consists of probes labelled in green, covering the Constant, J, D and Variable segments of the IGH gene, and CCND3 probes, labelled in red. The CCND3 probe mix contains a 158kb probe telomeric to the CCND3 gene, including the D6S1017 marker and a second probe covering the 244kb region centromeric to the TAF8 gene, including the D6S400 and the D6S1463 markers.
The CCND3 (cyclin D3) gene is located at 6p21.1 and IGH (immunoglobulin heavy locus) at 14q32.33.
Approximately 50-60% of multiple myeloma (MM) cases are associated with translocations involving IGH and one of several partners including CCND1, NSD2 (MMSET) and FGFR3, CCND3, MAF or MAFB1.
The t(6;14)(p21;q32) translocation is a recurrent translocation seen in 4% of cases of MM2.
CCND3 has been identified as a putative oncogene that is dysregulated as a consequence of the t(6;14)(p21;q32) translocation2. The translocation appears to be mediated by an error in IgH switch recombination as it has been shown that in KMM-1 cell lines, the translocation disrupts a switch sequence in this region and results in juxtaposition of CCND3 with the IGH promoter, thus elevating the levels of CCND3 expression2. It is thought that this mechanism is similar in all cases of IGH translocation. Most breakpoints appear to be clustered in a region that is fewer than 200kb centromeric to CCND32.
CCND3-IGH translocations are also reported in a variety of other B-cell malignancies, including plasma cell leukaemia, diffuse large B-cell lymphoma (DLBCL) and splenic lymphomas with villous lymphocytes (SLVL)3.
Running our PETS protocol was taking upwards of 5 hours to complete based on the previous SOP. After the technical training visit from CytoCell, we were able to make some tweaks to reduce the protocol time down to just 1 hour and 15 minutes, with the same or better results.
Assistant Genetic Technologist, Leicestershire Genetics Centre, UK