Translocations involving the immunoglobulin heavy-chain locus are possible early genetic events in patients with primary systemic amyloidosis

Primary systemic amyloidosis (AL) is a plasma cell (PC) dyscrasia with clinical similarities to multiple myeloma (MM) and monoclonal gammopathy of undetermined significance (MGUS), but its molecular basis is poorly understood. Translocations at the immunoglobulin heavy-chain (IgH) locus, 14q32, are likely early genetic events in both MM and MGUS and involve several nonrandom, recurrent, partner chromosomes such as 11q13, 16q23, and 4p16.3. Given the similarities between MM, MGUS, and AL, bone marrow clonal PCs were evaluated in 29 patients with AL using interphase fluorescence in situ hybridization (FISH) combined with immunofluorescence detection of the cytoplasmic light-chain (cIg-FISH) for the presence of 14q32 translocations and the t(11;14)(q13;q32). Of 29 patients studied, 21 (72.4%) showed results compatible with the presence of a 14q32 translocation, and 16 (76.2%) of those had translocation (11;14)(q13;q32) for an overall prevalence of the abnormality of 55%. IgH translocations are common in AL, especially the t(11;14)(q13;q32).     

Close relation between 14q32/IGH translocations and chromosome 13 abnormalities in multiple myeloma: a high incidence of 11q13/CCND1 and 16q23/MAF

Many B-cell tumors have chromosomal translocations that result from failures of the immunoglobulin (Ig) gene during V(D)J recombination, somatic hypermutation (SHM), and class switch recombination (CSR). Nearly half of all multiple myeloma (MM) patients have 14q32/IGH translocations in CSR, including the five common translocations of 11q13/CCND1, 6p21/CCND3, 4p16/FGFR3, 16q23/MAF, and 20q11/MAFB. Although 14q32/IGH translocations are closely related to the biological features of MM, the most consistent and powerful prognostic factor has been reported to be the loss of all (monosomy 13/−13) or part of chromosome 13 (del(13)(q14)/13q−). Our fluorescence in situ hybridization (FISH) analysis method was designed to detect −13/13q− and 14q32/IGH rearrangements in 23 MM patients. FISH disclosed 14q32/IGH translocations in 10 of the 23 (43.5%) patients. The common translocation partners of 14q32/IGH were 11q13/CCND1 (five patients) and 16q23/MAF (four patients), followed in third place by 4p16/FGFR3 (one patient). Nine of the ten patients carrying 14q32/IGH translocations had −13/13q−. Abnormalities of chromosome 13 included −13 in seven (70%) and del(13)(q14) in two (20%). Our results suggest a significant correlation between the presence of 14q32/IGH translocations and chromosome 13 abnormalities (P = 0.0276) in MM patients.     

Genomic abnormalities in monoclonal gammopathy of undetermined significance

Translocations involving immunoglobulin (Ig) loci and chromosome 13 monosomy (Delta 13) are frequent cytogenetic findings in multiple myeloma (MM). Similar chromosomal aberrations have been identified in the monoclonal gammopathy of undetermined significance (MGUS), but their prevalence and significance remain uncertain. Bone marrow from 72 patients with MGUS (n = 62) and smoldering MM (n = 10) was evaluated for translocations between the Ig heavy chain (IgH) and chromosomes 4, 11, and 16, translocations involving Ig light chain-lambda (IgL-lambda, and Delta 13. Fluorescence in situ hybridization (FISH) analysis was done on clonal plasma cells (PCs) detected by immunofluorescence (cIg-FISH) of the cytoplasmic light chain. We also studied cells for cyclin D1 and FGFR3 up-regulation by immunohistochemistry and immunofluorescence, respectively. Twenty-seven (46%) of 59 patients had IgH translocations, and 4 (11%) of 37 had an IgL-lambda translocation. A t(11;14)(q13;q32) was found in 15 (25%) of 59 patients, a t(4;14)(p16.3;q32) in 9% of patients, and a t(14;16)(q32;q23) in 5% of patients. All patients with t(4;14)(p16.3;q32) tested (n = 3) had intense cytoplasmic fluorescence with an anti-FGFR3 antibody. PC nuclear staining of cyclin D1 was only observed in patients with t(11;14)(q13;q32); Delta 13 was detected in the clonal PCs in 50% of patients. The percentage of abnormal PCs varied with any given abnormality. No obvious clinical or biologic correlations were associated with these chromosome abnormalities. Similar translocations are found in both MGUS and MM, including t(4;14)(p16.3;q32) and t(14;16)(q32;q23). Moreover, Delta 13 is common in MGUS and unlikely to play a predominant role in the evolution of MGUS to MM.     

Cytogenetics of multiple myeloma: interpretation of fluorescence in situ hybridization results

The cytogenetic picture in multiple myeloma (MM) is highly complex, from which non-random numerical and structural chromosomal changes have been identified. Specifically, translocations involving the immunoglobulin heavy chain gene (IGH) at 14q32 and either monosomy or deletions of chromosome 13 have been reported in a significant number of patients from both cytogenetic and interphase fluorescence in situ hybridization (FISH) studies. Importantly, these abnormalities of chromosome 13 have recently been associated with a poor prognosis. In view of the highly complex nature of the karyotypes in MM patients, interphase FISH results may be difficult to interpret. In this study, cytogenetics and/or interphase FISH were carried out on bone marrow samples or purified plasma cells from 37 MM patients. Abnormal karyotypes, characterized by multiplex FISH (M-FISH) were found in 11 patients, all of which were highly complex. Interphase FISH revealed translocations involving the IGH locus in 16 (43%) patients. The IGH/cyclin D1 (CCND1) gene fusion characteristic of the translocation, t(11;14)(q13;q32), was seen in 12 (32%) of these patients and other rearrangements of IGH in four (11%) patients. Fourteen patients had additional copies of chromosome 11. Twenty patients (54%) had 13q14 deletions, 10 of whom also had t(11;14) or another IGH translocation. By comparing cytogenetic and FISH results, this study has revealed that significant chromosomal abnormalities might be hidden within highly complex karyotypes. Therefore, extreme caution is required in the interpretation of interphase FISH results in MM, particularly in relation to certain abnormalities, such as 13q14 deletions, which have an impact on prognosis.     

Oncogenesis of multiple myeloma: 14q32 and 13q chromosomal abnormalities are not randomly distributed, but correlate with natural history, immunological features, and clinical presentation

Multiple myeloma (MM) is a plasma-cell malignancy characterized by marked epidemiological, biological, and clinical heterogeneity. The goal of this study was to find a genetic basis for this heterogeneity. Using fluorescence in situ hybridization, we analyzed a prospective cohort of 901 patients with various plasma-cell disorders--monoclonal gammopathies of undetermined significance, smoldering MM, MM, and primary plasma-cell leukemia--for genetic abnormalities involving the 13q14 and 14q32 chromosomal regions; the patients were consecutively enrolled in the Intergroupe Francophone du Myélome clinical trials, We performed statistical analyses comparing these chromosomal abnormalities in terms of immunological (ie, immunoglobulin types and light-chain subtypes) and clinical status and, to some extent, prognostic features. It was found that 14q32 translocations and del(13) are the most frequent chromosomal abnormalities, observed in 75% and 45% of the patients, respectively, and are not randomly distributed, but interconnected. Second, correlations between them allowed us to define 4 major genetic categories of patients: (1) patients lacking any 14q32 abnormality (25%) and generally also lacking del(13); (2) patients presenting either t(4;14) or t(14;16), almost always associated with a del(13) (15% of patients); (3) patients with other 14q32 abnormalities and presenting del(13) (25%); and (4) patients with other 14q32 abnormalities but not presenting del(13) (35%). Third, we show that this genetic stratification is highly correlated with immunological status and clinical presentation and with some major prognostic factors. For the first time, this study gives genetic support to the heterogeneity observed in patients with MM and demonstrates that the 14q32 and 13q chromosomal abnormalities are not randomly distributed. The strong correlations we found might be the basis for a novel genetic classification of MM, as has been previously demonstrated for leukemias and lymphomas. Furthermore, our study supports different models for MM oncogenesis.     

Chromosome aberrations in a series of 120 multiple myeloma cases with abnormal karyotypes

We identified 120 multiple myeloma (MM) cases with satisfactory cytogenetic evaluation and abnormal karyotypes. Hyperdiploid karyotype was found in 77 cases (64%), hypodiploid in 30 cases (25%), and the remaining 13 cases (11%) had a pseudodiploid karyotype. The most common numerical abnormalities were gains of chromosomes 15, 9, 3 followed by chromosomes 19, 11, 7, 21, and 5. Whole chromosome losses were also frequent involving primarily chromosomes X/Y, 8, 13, 14, and 22. Most cases showed also structural rearrangements leading to del(1p), dup(1q), del(5q), del(6q), del(8p), del(9p), del(13q), and del(17p). Chromosome 13/13q deletion was found in 52% of cases; complete loss of 13 was observed in 73% of cases, whereas 27% had interstitial deletions. In addition, 13/13q deletions occurred in 75% of nonhyperdiploid myeloma but only 39% of the hyperdiploid had 13/13q deletions. Translocations affecting 14q32/IGH region was seen 40 cases; t(11;14)(q13;q32) in 17 cases, t(14;16)(q32;q23) and t(8;14)(q24;q32) in three cases each, and t(6;14)(p21;q32) and t(1;14)(q21;q32) in two cases each. The remaining 14q32 translocations had various t(V;14) partners or of an undetermined origin. Remarkably, the 14q32/IGH translocations were less frequent in the hyperdiploid karyotypes than the nonhyperdiploid karyotypes (17 vs. 63%). Fourteen cases showed break at 8q24/CMYC site; seven of those had Burkitt's-type translocations. Our results revealed that conventional cytogenetics remains an important tool in elucidating the complex and divers genetic anomalies of MM. Cytogenetics identifies two distinct groups of MM, hyperdiploid and nonhyperdiploid, and establishes the presence of prognostic chromosomal markers such as 13/13q, 17p, 8q24, and 16q aberrations.     

Recurrent 14q32 translocations determine the prognosis of multiple myeloma,especially in patients receiving intensive chemotherapy

Recently, we have described the biological correlations associated with the main translocations involving the 14q32 chromosomal region, that is, t(14q32), in patients with multiple myeloma (MM). We have now extended the analysis to the prognostic value of these chromosomal rearrangements in 168 consecutive patients with newly diagnosed MM receiving intensive chemotherapy within clinical trials of the Intergroupe Francophone du Myelome (IFM). Patients with t(4;14) displayed a poor outcome (short event-free survival and short overall survival), whereas those with t(11;14) displayed long survival. On the other hand, patients with neither t(4;14) nor t(11;14) presented an intermediate outcome. Importantly, chromosome 13 abnormalities (C13As) significantly influence the prognosis of this latter group. In contrast, C13As affected the outcome of the other patients to a much lesser extent, either because of an almost constant association (in the t(4;14) group) or because of a lack of any significant prognostic impact (in the t(11;14) group; only one event occurred in the 10 patients with t(11;14) and C13As). Considering that t(4;14) and t(11;14) (1) are the only (so far recognized) true, recurrent t(14q32)'s, (2) are linked to specific immunoglobulin isotypes, and (3) display specific outcomes, they represent distinct entities corresponding to a specific oncogenesis and prognosis. These data emphasized the interest in analyzing these two translocations by fluorescence in situ hybridization in prospective therapeutic trials in order to consider these translocations as distinct entities.     

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.     

t(14;22)(q32;q11) in non-Hodgkin lymphoma and myeloid leukaemia: molecular cytogenetic investigations

Two non-Hodgkin lymphomas (NHL), one chronic lymphocytic leukaemia/small lymphocytic lymphoma and one diffuse large B-cell lymphoma and three cases of myeloid leukaemia, two chronic (CML) and one acute (AML), showed, by G-banding analysis, apparently identical chromosomal translocations t(14;22)(q32;q11), in three of the cases as the sole abnormality. Fluorescence in situ hybridisation (FISH) analysis with locus-specific probes for ABL at 9q34 [bacterial artificial chromosomes (BACs) 835J22 and 1132H12], IGH at 14q32 [P1 artificial chromosome (PAC) 998D24] and IGL (PAC 1019H10) and BCR (BAC 74M14) at 22q11, as well as multicolour in situ hybridisation (M-FISH) analyses were performed. A three-way variant translocation of the classical t(9;22)(q34;q11), t(9;22;14)(q34;q11;q32), involving both BCR and ABL, was unravelled by the molecular cytogenetic investigations in the three myeloid leukaemia cases; a similar variant translocation has previously been reported in seven CML. The two cases of NHL (one NHL with a similar 14;22-translocation has been reported previously) had no involvement of BCR or ABL, but instead the IGH and IGL genes were shown to be juxtaposed by the t(14;22)(q32;q11). How such a rearrangement with recombination of IGH and IGL might elicit a pathogenetic effect is completely unknown.     

Chromosome translocations involving band 7q35 or 7p15 in childhood T- cell leukemia/lymphoma

In a chromosome study in childhood T-cell leukemia/lymphoma, we found t(7;11)(q35;p13) in 2 patients, t(7;14) (q35;q11) in one patient, and t(7;14)(p15;q32) in 1 patient. Southern blotting and in situ chromosomal hybridization studies in one patient with the t(7;11) demonstrated that both alleles of the T-cell antigen receptor beta- subunit gene (TCRB) were rearranged, and that one TCRB allele had relocated from 7q35 to the fusion point in band p13 of the involved chromosome 11 (11p-). These findings suggest that juxtaposition of TCRB with the putative oncogene tcl-2 located in band 11p13 may be a critical step toward development of this T-cell leukemia/lymphoma. In the other two translocations, all breakpoints were sites for lymphocyte function genes, ie, 7q35 for TCRB, 14q11 for T-cell antigen receptor alpha-subunit gene (TCRA), 7p15 for T-cell antigen receptor alpha- subunit gene (TCRG), and 14q32 for immunoglobulin heavy-chain gene (IGH). Thus, the findings in these cases allow us to expand the above hypothesis and propose that the juxtaposition of TCRB or TCRG with tcl- 2, TCRA, or IGH through chromosomal translocation may activate a mechanism for the genesis of T-cell leukemia/lymphoma with these chromosome translocations.     

Monosomy 13 is associated with the transition of monoclonal gammopathy of undetermined significance to multiple myeloma. Intergroupe Francophone du Myélome.

Chromosomal abnormalities are present in most (if not all) patients with multiple myeloma (MM) and primary plasma cell leukemia (PCL). Furthermore, recent data have shown that numerical chromosomal changes are present in most individuals with monoclonal gammopathy of undetermined significance (MGUS). Epidemiological studies have shown that up to one third of MM may emerge from pre-existing MGUS. To clarify further possible stepwise chromosomal aberrations on a pathway between MGUS and MM, we have analyzed 158 patients with either MM or primary PCL and 19 individuals with MGUS using fluorescence in situ hybridization (FISH). Our FISH analyses were designed to detect illegitimate IGH rearrangements at 14q32 or monosomy 13. Whereas translocations involving the 14q32 region were observed with a similar incidence (60%) in both conditions, a significant difference was found in the incidence of monosomy 13 in MGUS versus MM or primary PCL. It was present in 40% of MM/PCL patients, but in only 4 of 19 MGUS individuals. Moreover, whereas monosomy 13 was found in the majority of plasma cells in MM, it was observed only in cell subpopulations in MGUS. It is noteworthy that, in a group of 20 patients with MM and a previous MGUS history, incidence of monosomy 13 was 70% versus 31% in MM patients without a known history of MGUS (P =.002). Thus, this study highlights monosomy 13 as correlated with the transformation of MGUS to overt MM and may define 2 groups of MM with possible different natural history and outcome, ie, post-MGUS MM with a very high incidence of monosomy 13 and de novo MM in which other genetic events might be involved. Serial analyses of individuals with MGUS will be needed to validate this model.     

Chromosome 14q32 translocations involving the immunoglobulin heavy chain locus in chronic lymphocytic leukaemia identify a disease subset with poor prognosis

Immunophenotypic studies, fluorescence in situ hybridization (FISH) and conventional karyotyping were used to define the clinicobiological significance of 14q32 translocations involving the immunoglobulin gene locus (14q32/ IGH ) in 252 chronic lymphocytic leukaemia (CLL) patients. The following regions were studied: 13q14, centromere 12, 6q21; 11q22/ ATM ; 17p13/ TP53 , 14q32/ IGH . Patients were classified as group 1 (favourable, i.e. 13q-single or normal), group 2 (intermediate risk, i.e. +12, 6q-, 1–2 anomalies), group 3 (unfavourable, i.e. 17p-, 11q-, complex karyotype), or group 4 (14q32/ IGH translocation). Endpoints were treatment-free survival (TFS) and overall survival (OS). One hundred and ten patients were included in group 1, 99 in group 2, 25 in group 3 and 18 in group 4. 14q32/ IGH translocation partners were identified in eight cases ( BCL2 in five cases, BCL11A , CCND3 and CDK6 in one case each). group 4 showed shorter TFS versus groups 2 and 1 (25% patients treated at 2 months vs. 12 ( P  = 0·02) and 20 months ( P  = 0·002), respectively) and shorter OS (25% patients dead at 18 months versus 50 ( P  = 0·0003) and >60 months ( P  < 0·0001) respectively. The 14q32/ IGH translocation maintained prognostic significance at multivariate analysis on TFS ( P  = 0·025) and OS ( P  < 0·001), along with advanced stage and CD38⁺. These findings show that the 14q32/ IGH translocation predicts for an unfavourable outcome in CLL and that this cytogenetic subset might be included as a separate entity in a hierarchical cytogenetic classification of CLL.     

The t(14;20) is a poor prognostic factor in myeloma but is associated with long-term stable disease in monoclonal gammopathies of undetermined significance

A large series of plasma cell dyscrasias (n=2207) was examined for translocations which deregulate the MAF genes, t(14;20)(q32;q12) and t(14;16)(q32;q23), and their disease behavior was compared to a group characterized by the t(4;14)(p16;q32) where CCND2 is also up-regulated. The t(14;20) showed low prevalence in myeloma (27/1830, 1.5%) and smoldering myeloma (1/148, <1%) with a higher incidence in MGUS (9/193, 5% P=0.005). Strong associations with del(13) (76%), non-hyperdiploidy (83%) and gain of 1q (58%) were seen but no association with an IgA M-protein or absence of bone disease was noted. All three translocations were associated with poor outcome in myeloma, but strikingly all t(14;20) MGUS/smoldering myeloma cases (n=10) had stable, low level disease. In contrast, the 10 t(14;16) and 25 t(4;14) MGUS/smoldering myeloma cases were associated with both evolving and non-evolving disease. None of the associated genetic abnormalities helped to predict for progression from MGUS or smoldering myeloma. (Clinicaltrials.gov identifier: ISRCTN 68454111; UKCRN ID 1176)     

Acquisition of t(11;14) in a patient with chronic lymphocytic leukemia carrying both t(14;19)(q32;q13.1) and +12

A rare recurrent chromosomal translocation, t(14;19)(q32;q13), has been identified in a variety of B‐cell malignancies, including chronic lymphocytic leukemia (CLL). We report a unique case of CLL in a patient carrying both trisomy 12 and t(14;19) (q32;q13.1), in whom t(11;14)(q13;q32) developed at relapse. The patient was a 77‐yr‐old woman, and her lymphoma cells at presentation showed CD5⁺, CD10^?, CD19⁺, CD20⁺(dim), CD23⁺, CD38⁺, and CD11c⁺. At relapse, the patient's lymphoma cells showed positive staining for cyclin D1 in addition to CD5, CD20, and CD23. Lymphoma cells in specimens at both presentation and relapse were positive for lymphoid enhancer factor 1 (LEF1) and negative for sex‐determining region Y‐box 11 (SOX11). IGH‐BCL1 FISH became positive at relapse. Split FISH assay using BCL1, BCL3, IGH, and CCND1 probes on lymph node specimens obtained at presentation and at autopsy confirmed that the translocation of BCL3 was solely detected in the lymph node at presentation and detected BCL3 and CCND1 translocations in the specimen at autopsy. These observations indicated that IGH‐BCL3 and IGH‐CCND1 had occurred in the same clone after treatment of the disease. In line with immunohistochemical and cytogenetic studies, additional PCR analysis of the FR3‐JH region showed the same sequence derived from IGHV4‐34 in specimens obtained at disease onset and relapse.     

Nonrandom chromosomal rearrangements of 14q32.3 and 19p13.3 and preferential deletion of 1p in 21 patients with multiple myeloma and plasma cell leukemia

Structural chromosomal abnormalities and their break-points were characterized in 17 patients with multiple myeloma (MM) and 4 with plasma cell leukemia by banding. Chromosome 14q32 translocations with a variety of partners were detected in 13 patients, and a variant translocation t(8;22)(q24.1;q11) was detected in 1. Three recurrent 14q32 translocations have been identified: t(6;14)(p21.1;q32.3) occurring in 3 cases, and t(11;14)(q13;q32.3) and t(14;18) (q32.3;q21.3) each occurring in 2 cases. Translocations t(1;14)(q21;q32.3), t(3;14)(p11;q32),t(7;14)(q11.2;q32.3), and t(11;14)(q23;q32.3) were found in each patient, whereas in the remaining 2 patients, partner chromosomes could not be determined. The band 19p13.3 was newly delineated as a recurrent breakpoint involved in translocations in MM. Chromosomes 1 and 6 were also commonly involved in structural abnormalities (14 and 10 patients, respectively), although no particular bands were noted. However, the short arm of chromosome 1 was preferentially involved in deletion, suggesting a certain antioncogene on 1p associated with the development of myeloma. In addition; fluorescence in situ hybridization was successfully applied to determine the nature of the structural abnormalities in a patient with t(8;22) translocation. The present findings suggest that there may be subsets of 14q32 translocations specific to MM.     

Large variation in t(11;14)(q13;q32) and t(14;18)(q32;q21) translocation product size is confirmed by sequence analysis of PCR products

Polymerase chain reaction is commonly used to detect t(11;14)(q13;q32) and t(14;18)(q32;q21) chromosomal translocations associated with mantle cell lymphoma and follicular lymphoma. We tested a total of 482 samples from patients with suspected non-Hodgkin's lymphoma and sequenced unusual-sized t(11;14)(q13;q32) and t(14;18)(q32;q21) products from 33 of these patients. BCL-1 or BCL-2 gene rearrangements were confirmed in 23 of 33 patients (70%). Considerable size variation was observed using t(11;14) primers, with MTCA and MTCB t(11;14) products ranging from 234 to 934 bp and 143 to 560 bp respectively. Less variability was observed for t(14;18) Major Breakpoint Region (MBR) products (100-252 bp) but Minor Cluster Region (MCR) products ranged from 217 to 498 bp. We demonstrate the utility of sequence analysis to confirm unusual-sized translocation products and reduce false-positive results because of nonspecific amplification.     

Evaluation of the cytogenetic aberration pattern in amyloid light chain amyloidosis as compared with monoclonal gammopathy of undetermined significance reveals common pathways of karyotypic instability

Chromosomal aberrations (CAs) have emerged as important pathogenetic and prognostic factors in plasma cell disorders. Using interphase fluorescence in situ hybridization (FISH) analysis, we evaluated CAs in a series of 75 patients with amyloid light chain amyloidosis (AL) as compared with 127 patients with monoclonal gammopathy of unknown significance (MGUS). We investigated IgH translocations t(11;14), t(4;14), and t(14;16) as well as gains of 1q21, 11q23, and 19q13 and deletions of 8p21, 13q14, and 17p13, detecting at least one CA in 89% of the patients. Translocation t(11;14) was the most frequent aberration in AL, with 47% versus 26% in MGUS (P = .03), and was strongly associated with the lack of an intact immunoglobulin (P < .001), thus contributing to the frequent light chain subtype in AL. Other frequent aberrations in AL included deletion of 13q14 and gain of 1q21, which were shared by MGUS at comparable frequencies. The progression to multiple myeloma (MM) stage I was paralleled by an increased frequency of gain of 1q21 (P = .001) in both groups. Similar branching patterns were observed in an oncogenetic tree model, indicating a common mechanism of underlying karyotypic instability in these plasma cell disorders.     

Long-term follow up with conventional cytogenetics and band 13q14 interphase/metaphase in situ hybridization monitoring in monoclonal gammopathies of undetermined significance

One-third of patients with monoclonal gammopathy of undetermined significance (MGUS) may progress to multiple myeloma (MM) and may develop a long arm deletion of chromosome 13 (13q-). As the incidence of 13q-, time of development and prognostic impact in MGUS patients is still under debate, we decided to perform serial sequential conventional cytogenetics (CC) and metaphase/interphase fluorescence in situ hybridization (FISH) analyses on bone marrow mononuclear cells obtained from 18 asymptomatic, untreated MGUS patients. Median follow up was 30 months (range 6-72). Interphase FISH identified a 13q14 deletion in five out of 18 patients (on clinical diagnosis in one patient and during the follow up in the remaining four patients). Subsequently, metaphase FISH and CC also identified the deletion in four out of five patients. All five of the patients progressed to MM 6-12 months after 13q- identification, without developing any FISH determined JH rearrangements. MM progression also occurred in two other karyotypically normal patients. We conclude that: (i) the extent of the 13q deletion does not vary during the clinical outcome; (ii)13q- plays a crucial role in MGUS/MM pathogenesis and confers a proliferative advantage to clonal plasma cells being initially demonstrated by interphase FISH and only afterwards by metaphase FISH and CC; and (iii) association of 13q- with t(4;14)(p16.3;q32) remains to be demonstrated. However, a transition from MGUS to MM may also occur in patients with normal karyotypes or other abnormalities, suggesting the possibility of distinct pathogenetic pathways.     

Molecular cytogenetic aberrations in 21 Chinese patients with plasma cell leukemia

Plasma cell leukemia (PCL) is a rare malignant plasma cell disorder. Cytogenetic studies performed on plasma cell disorders are scarce and difficult because of the low proliferation rate of plasma cells (PCs). Fluorescence in situ hybridization (FISH) analysis is an attractive alternative for evaluation of chromosomal changes in PCL. To explore the molecular cytogenetic abnormalities in Chinese patients with PCL, interphase FISH studies with three probes for the regions containing 13q14.3 (D13S319), 14q32 (IGHC/IGHV) and 1q12(CEP1) were retrospectively performed in 21 PCL patients. FISH with LSI IGH/CCND1 and LSI IGH/FGFR3 probes were used to detect t(11;14)(q13;q32) and t(4;14)(p16;q32) in patients with 14q32 rearrangement. Among 21 PCL patients, molecular cytogenetic aberrations were found in 18 (81.8%) patients, four (19.0%) patients simultaneously had 13q14 deletion, illegitimate IgH translocation and 1q abnormality. 13q14 deletion was detected in 13 (61.9%) cases and illegitimate 14q32 rearrangement in 16 (76.2%) including six with t(11;14) and three with t(4;14). Chromosome 1 abnormality was found in seven (33.3%) patients, one with deletion of 1q, six with at least three copies amplifications of 1q12 (Amp1q12). 14q32 rearrangement and 13q14 deletion were found concurrently in 11 (52.4%) cases. It was showed that most PCL had chromosomal abnormalities, 14q32 rearrangement, 13q14 deletion and chromosome 1 abnormality are the frequent abnormalities, and over half of the 14q32 rearrangement were t(11;14) or t(4;14). t(4;14) and 13q14 deletion were correlated in PCL. FISH is a highly sensitive technique at detecting molecular cytogenetic aberrations in PCL and should be used in the routine evaluation of PCL.