The IGH/MAFB Plus product consists of probes, labelled in green, proximal to the Constant, and within the Variable segment of the IGH region and MAFB probes (195kb, 161kb and 401kb), labelled in red. The MAFB probes are located on either side of the breakpoint region (between MAFB and PPP1R16B).
The MAFB (MAF bZIP transcription factor B) gene is located at 20q12 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(14;20)(14q32;q12) translocation is a recurrent translocation seen in around 2% of MMs2,3.
The reciprocal rearrangement brings a truncated form of the IGH μ-enhancer (Eμ, located between the joining (J) segments and the constant region of the IGH gene) in close contact with the MAFB gene4. The resultant fusion and the up-regulated transcription product has been shown to cause dysregulation of cyclin D21.
The prognostic outcome of t(14;20)(14q32;q12) is assumed to be the same as the t(14;16)(q32;q23)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