TRANSLOCATION T(14;16): FREQUENCY AND SIGNIFICANCE IN PATIENTS WITH MULTIPLE MYELOMA

Aims:

The goals were to determine the frequency of translocation t(14;16) and to analyze cytogenetic, molecular cytogenetic and clinical data in a group of patients with MM or monoclonal gammopathy of undetermined significance (MGUS) diagnosed and treated at the Department of Internal Medicine III and cytogenetically investigated at the Department of Hemato-Oncology, University Hospital Olomouc in 2000-2013.

Methods:

In all MM or MGUS patients, bone marrow was tested by conventional cytogenetic methods and FISH with locus-specific, centromeric, whole chromosome and BAC probes; one patients was investigated using mFISH and arrayCGH.

Results:

Translocation t(14;16) was found in 10 (2.9%) out of a total of 339 patients investigated for IgH gene rearrangement. The group of 10 patients comprised 5 males and 5 females with a median age of 67 years. The only monoclonal immunoglobulin isotype detected in the patients’ blood serum was the IgG isotype; in two patients, a Bence Jones protein was detected. The ratio of kappa to lambda free light chains was 5:5. Using the Durie-Salmon staging system, clinical stage I was found in 2 patients and stages II and III in 3 and 5 patients, respectively. Significant renal insufficiency was observed in 3 patients.

Cytogenetic and molecular cytogenetic assays revealed other additional changes in all 10 patients with s t(14;16): deletion of the RB1 gene (7 patients), trisomy or tetrasomy of chromosome 15 (7 patients) and structural and numerical aberrations of chromosome 8 (7 patients). To determine the frequently altered regions of chromosomes 8p and 8q, BAC-specific probes were used as follows: 8p23.1 (RP11-589N15), 8p21.3 (RP11-177H13), 8q24.21 (MYCFISH DNA probe), 8q24.3 (RP11-639O3), RP11-639O3 (8q24.3) and a chromosome 8 centromere probe. The most frequently detected chromosome 8 aberration was deletion of the short arm region (8p21.3).

Summary / Conclusion:

Cytogenetic and molecular cytogenetic analysis of 339 patients with MM or MGUS confirmed a low incidence of t(14;16) (2.9%). In no patient, this was the only aberrations; it was a part of complex changes in 9 out of 10 patients. Recurrent aberrations in the complex karyotype of patients with t(14;16) were aberrations of chromosomes 13, 15 and 8. Out of 10 patients, only 2 are alive, with the OS rates of 5 and 20 months, confirming the adverse prognostic significance of this aberration in this small group of patients.

Supported by Palacký University student research grant no. LF-2013-004

Keywords: Cytogenetics, Fluorescence in situ hybridization, Multiple myeloma, Translocation

Abstrakta v časopise Haematologica 2013, Suppl1

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