Diagnostic role and prognostic significance of a simplified immunophenotypic classification of mature B cell chronic lymphoid leukemias.

We verified the diagnostic and prognostic role of a simplified immunophenotypic classification (IC) in a series of 258 patients (M/F: 1.4; median age: 64 years; median follow-up: 64 months; 75 deaths) with mature B cell lymphoid leukemias (MBC-LL) for whom no histopathological diagnosis was available because of minimal or no lymph node involvement. The IC was based on the reactivity of three pivotal immunophenotypic markers: CD5, CD23 and SIg intensity. On the basis of different expression patterns, we identified four diagnostic clusters (C) characterized by distinct clinico-biological features and different prognoses: C1 (149 patients) identified most classical B cell chronic lymphocytic leukemias (CLL-type cluster; SIg(dim)/CD5+/CD23+); C2, 38 patients whose clinico-hematological characteristics were intermediate between C1 and C3 (CLL-variant cluster; SIg(bright)/CD5+/CD23+/-or SIg(dim)/CD5-/-/CD23 indifferent); C3 (16 patients) most situations consistent with mantle cell lymphoma in leukemic phase (MCL-type cluster; SIg(bright)/CD5+/CD23-); and C4, 55 cases, most of whom were consistent with leukemic phase lymphoplasmacytic/splenic marginal zone lymphomas (LP/S-type cluster; SIg(bright)/CD5-/+/CD23 indifferent). At univariate survival analysis, prognosis worsened from C1 to C4, C2 and C3 (P = 0.0001), and this was maintained at multivariate analysis (P = 0.006), together with CD11c expression (P = 0.0043), age at diagnosis (cut-off 70 years; P = 0.0008) and platelet count (cut-off 140 x 10(9)/l; P = 0.0034). Besides recognising the two well-known situations of classic B-CLL and MCL, our IC identified situations with distinct prognostic and/or clinical behaviors.

Analysis of FGFR3 gene mutations in multiple myeloma patients with t(4;14).

The t(4;14)(p16.3;q32) in multiple myeloma (MM) leads to an apparent deregulation of the FGFR3 and WHSC1/MMSET genes. FGFR3 mutations, known to be associated with genetic skeletal disorders, have also been identified in a few cases of MM (mainly cell lines) with t(4;14). We investigated FGFR3 mutations in a series of 53 MM cases; 11 cases with t(4;14) and FGFR3 overexpression were analysed using reverse transcription polymerase chain reaction, while the remaining cases were studied at DNA level. The Arg248Cys mutation, which is associated with some lethal forms of skeletal disorders, was found in one case with t(4;14). Our results indicate that FGFR3 mutations occur in only a small fraction of MM cases with t(4;14).

Translocation T(4;14)(p16.3;q32) is a recurrent genetic lesion in primary amyloidosis.

Primary amyloidosis is a fatal disorder characterized by low numbers of clonal plasma cells in the bone marrow and the systemic deposition of light chain fragments in the form of amyloid. The molecular pathobiology of amyloidosis is primarily unknown. Recently, a novel karyotypically undetectable t(4;14)(p16.3;q32) translocation has been identified in approximately 20% of multiple myeloma patients. The translocation leads to the apparent deregulation of two genes located on 4p16.3, the fibroblast growth-factor receptor 3 (FGFR3), and the putative transcription factor multiple myeloma SET domain (MMSET), and to the generation of IGH/MMSET hybrid transcripts. In this study, we investigated the presence of the t(4;14) translocation in 42 AL patients using a reverse transcriptase-polymerase chain reaction assay for the detection of IGH/MMSET transcripts. Chimeric transcripts were found in six patients (14%) and were consistent with a 4p16.3 breakpoint involving intron 3 and juxtaposing IGH regions to exon 4. In three of these cases, hybrid transcripts juxtaposing IGH regions to exon 5 were also observed and were probably the result of an alternative splicing skipping exon 4. Because all of the fusion transcripts (six of six) excluded exon 3, the first translated MMSET exon, only putative 5' truncated MMSET proteins could be generated. In conclusion, our results demonstrate that the t(4;14)(p16.3;q32) translocation is a recurrent genetic lesion in primary amyloidosis.

BCL10 gene mutations rarely occur in lymphoid malignancies.

BCL10, a gene involved in apoptosis signalling, has recently been identified through the cloning of chromosomal breakpoints in extranodal (MALT-type) marginal zone lymphomas carrying the t(1;14)(p22;q32) translocation. BCL10 was also found mutated in these cases as well as in other types of lymphoid and solid tumors, suggesting that its inactivation may play an important pathogenetic role; however, this has been questioned by recent studies showing a lack of somatic mutations in human cancers. We report the mutation analysis of exons 1-3 of the BCL10 gene in DNAs from 228 cases of lymphoid malignancies (30 B cell chronic lymphocytic leukemias, 123 B and 45 T non-Hodgkin's lymphomas and 30 multiple myelomas). Somatic mutations were detected in four cases (approximately 2%): one small lymphocytic, one follicular and two diffuse large cell lymphomas. The mutations were all within exon 3 and have not been previously reported. Our data suggest that BCL10 mutations may play only a limited role in the pathogenesis of lymphoid neoplasms.

Detection of t(4;14)(p16.3;q32) chromosomal translocation in multiple myeloma by double-color fluorescent in situ hybridization.

Chromosomal translocations involving the immunoglobulin heavy chain (IGH) locus at chromosome 14q32 represent a common mechanism of oncogene activation in lymphoid malignancies. In multiple myeloma (MM), variable chromosome partners have been identified by conventional cytogenetics, including the 11q13, 8q24, 18q21, and 6p21 loci. We and others have recently reported a novel, karyotypically undetectable chromosomal translocation t(4;14)(p16. 3;q32) in MM-derived cell lines, as well as in primary tumors. The 4p16.3 breakpoints are relatively scattered and located less than 100 kb centromeric of the fibroblast growth factor receptor 3 (FGFR3) gene or within the recently identified WHSC1 gene, both of which are apparently deregulated by the translocation. To assess the frequency of the t(4;14)(p16.3;q32) translocation in MM, we performed a double-color fluorescent in situ hybridization (FISH) analysis of interphase nuclei with differently labeled probes specific for the IGH locus (a pool of plasmid clones specific for the IGH constant regions) or 4p16.3 (yeast artificial chromosome (YAC) 764-H1 spanning the region involved in breakpoints). Thirty MM patients, the MM-derived cell lines KMS-11 and OPM2, and six normal controls were examined. The identification of a t(4;14) translocation, evaluated as the presence of a der(14) chromosome, was based on the colocalization of signals specific for the two probes; a cutoff value of 15% (mean + 3 standard deviation [SD]) derived from the interphase FISH of the normal controls (range, 5% to 11%; mean +/- SD, 8.16 +/- 2.2) was used for the quantification analysis. In interphase FISH, five patients (one in clinical stage I, two in stage II, one in stage III, and a plasma cell leukemia) were found to be positive (approximately 15%). FISH metaphases with split or colocalized signals were detected in only two of the translocated cases and confirmed the pattern found in the interphase nuclei. Furthermore, in three of the five cases with the translocation, FISH analysis with the IGH joining probe (JH) showed the presence of the reciprocal product of the translocation [der(4) chromosome]. Overall, our study indicates that the t(4;14)(p16. 3;q32) chromosomal translocation is a recurrent event in MM tumors and may contribute towards the detection of this lesion and our understanding of its pathogenetic and clinical implications in MM.