Cytogenetic and molecular delineation of a region of chromosome 3q commonly gained in marginal zone B-cell lymphoma

Background and Objectives. Whole or partial trisomy 3 represents the most recurrent chromosomal abnormality occurring in marginal zone B-cell lymphoma (MZBCL), a distinct subtype of B-cell non-Hodgkin's lymphoma (NHL). By conventional cytogenetic analysis, unbalanced translocations involving chromosome 3 and leading to a partial trisomy 3q were identified in a series of 14 MZB-CL patients. Fluorescent in situ hybridization (FISH) experiments were then performed to characterize the breakpoints further and to delineate the extent of the 3q gained region more accurately. Design and Methods. We studied 14 cases of MZBCL combining cytogenetics and FISH techniques using specific probes for the long arm of chromosome 3, including the chromosome 3 alpha satellite probe, a representative panel of yeast artificial chromosome (YAC) clones mapping the chromosomal 3q region (3q11.2 to 3q23) and the chromosome 3 subtelomeric (3q29) probe. Results. In the 14 cases, additional chromosome 3q material was found to be involved in different unbalanced translocations with chromosomes 1, 6, 7, 8, 11, 13, 14, 15, 17, 19 and 2 1, leading to a derivative chromosome. None of the chromosomal abnormality juxtaposed the 3q regions with the heavy and/or light kappa and lambda immunoglobulin gene loci. Eight different breakpoints distributed between the 3q11.2 and the 3q13.32 regions were identified and a common 3q13.32-3q29 overrepresented region was delineated. Interpretation and Conclusions. These results suggest that this critical region may be of importance in the pathogenesis of MZBCL and support the hypothesis that a gene dosage effect rather than a specific gene disruption may be involved in the development of this disease.