Chromosomal rearrangement of the PAX-5 locus in lymphoplasmacytic lymphomawith t(9;14)(p13;q32)

B-cell non-Hodgkin's lymphoma (NHL) consists of heterogeneous subtypes base d on histologic, immunophenotypic, and clinical findings. Recent advances i n molecular biology have provided us new insights into the pathogenesis of this neoplasm at the genetic level, such as the deregulation of the protoon cogenes adjoining the immunoglobulin gene (Ig) loci, which is a specific ev ent in mature B-cell tumors. Moreover, involvement of certain protooncogene s corresponds to certain subtypes of NHL. Recently, we found that t(9;14)(p 13;q32) chromosomal translocation associated with lymphoplasmacytic lymphom a (LPL) juxtaposes PAX-5 gene encoding for an essential transcription facto r (BSAP: B-cell specific activator protein) for B-cell proliferation and di fferentiation to the Ig heavy chain gene (IgH) locus. This results in dereg ulated expression of the PAX-5 mRNA. We also developed a diagnostic FISH (f luorescence in situ hybridization) procedure which is able to detect 80% of the widely scattering 9p13 breakpoints involved in this translocation. Thu s, an understanding of the PAX-5 gene's physiological role in B-cell develo pment and the pathological role in tumorigenesis may lead to the optimal cl inical treatment strategy for LPL and LPL-derived diffuse large cell lympho ma(DLCL).