Structural alterations in chronic lymphocytic leukaemia. Cytogenetic and FISH analysis

In this study, we described cytogenetics and fluorescence in situ hybridization (FISH) analysis performed in chronic lymphocytic leukaemia (CLL) patients with structural alterations. Results were correlated with clinical characteristics. A total of 38 CLL patients: 16 cases with complex and 22 with simple karyotypes were studied. For comparison of clinical parameters, a control group of 78 CLL patients with normal karyotype and without FISH genomic alterations were also evaluated. We found 38 structural abnormalities not previously described in the literature, 28 (74%) of them were translocations. In cases with complex karyotypes, chromosomes 6, 8 and 13 were the most frequently involved in new alterations (nine each), followed by chromosomes 12, 14 and 15 (six each). Chromosome 8p was particularly involved in losses, being 8p21‐pter the commonest region of overlap. Cases with simple karyotypes, showed del(6q) as the most frequent alteration (39%). Del(9)(q11) was recurrent in our series. Analysis of clinical parameters showed significant differences in white blood count (p = 0.005) and platelet count (p = 0.015) between patients with structural alterations and the control group. In addition, patients with structural alterations had a significantly shorter time to first treatment (TFT) (29 months) than the control group (69 months) (p = 0.037). Cases with complex karyotypes had a lower proportion of patients in Rai 0 clinical stage (15.4% vs 75%) (p = 0.005) and higher β₂ microglobulin levels (3.3 vs 2.5 µg/mL) (p = 0.037) than those with simple karyotypes. Furthermore, a shorter TFT (13 months) and overall survival (56 months) in the complex karyotypes group compared with controls (69 and 144 months, respectively) (p = 0.015 and p = 0.005, respectively) were also found. Our results support the importance of cytogenetic analysis for clinical outcome in CLL and suggest that the diversity of genomic alterations is much greater than previously appreciated. Copyright © 2012 John Wiley & Sons, Ltd.     

Identification of a novel recurrent gain on 20q13 in chronic lymphocytic leukemia by array CGH and gene expression profiling

BackgroundThe presence of genetic changes is a hallmark of chronic lymphocytic leukemia (CLL). The most common cytogenetic abnormalities with independent prognostic significance in CLL are 13q14, ATM and TP53 deletions and trisomy 12. However, CLL displays a great genetic and biological heterogeneity. The aim of this study was to analyze the genomic imbalances in CLL cytogenetic subsets from both genomic and gene expression perspectives to identify new recurrent alterations.Patients and methodsThe genomic imbalances and expression levels of 67 patients were analyzed. The novel recurrent abnormalities detected with bacterial artificial chromosome array were confirmed by FISH and oligonucleotide microarrays. In all cases, gene expression profiling was assessed.ResultsCopy number alterations were identified in 75% of cases. Overall, the results confirmed FISH studies for the regions frequently involved in CLL and also defined a new recurrent gain on chromosome 20q13.12, in 19% (13/67) of the CLL patients. Oligonucleotide expression correlated with the regions of loss or gain of genomic material, suggesting that the changes in gene expression are related to alterations in copy number.ConclusionOur study demonstrates the presence of a recurrent gain in 20q13.12 associated with overexpression of the genes located in this region, in CLL cytogenetic subgroups.     

Validation of Western common recurrent chromosomal aberrations in Korean chronic lymphocytic leukaemia patients with very low incidence

In Asia, the incidence of chronic lymphocytic leukaemia (CLL) is lower than in Western countries. Only a few studies of CLL have been conducted in Korea, and no long‐term clinical outcome data are available. We assessed the frequency of common chromosomal aberrations in Korean CLL patients using interphase fluorescence in situ hybridization (FISH) and investigated their relationship to clinical outcomes. Between 2000 and 2011, conventional cytogenetic studies were performed in 58 patients, and FISH results were available in 48 patients. We used six DNA probes for the detection of del(13q14), trisomy 12, del(11q22), del(17p13), IGH rearrangement and del(6q23). Chromosomal aberrations were identified in 15 of 58 patients (26%) with conventional cytogenetic studies and in 25 of 48 patients (52%) with interphase FISH, including six patients with complex karyotypes. In contrast with the results of Western studies, trisomy 12 was the most common aberration, followed by IGH rearrangement, del(13q14), del(11q22) and del(17p13). Deletion of 6q23 was not observed, and isolated del(13q14) was less frequent than in Western studies. Compared with the other types of chromosomal aberrations, patients with del(11q22) and del(17p13) were more likely to be Rai stage 3–4 and Binet stage C, resulting in poor responses to chemotherapy and worse outcomes. In contrast, patient with trisomy 12 and isolated del(13q14) showed better responses and superior survival outcomes. The incidence of CLL is lower in Korea than in Western countries, and the frequency of chromosomal aberrations differs, perhaps reflecting differences in the pathogenic mechanism between ethnicities. Large prospective studies are needed to further assess the prognostic value of these results in Korean CLL patients. Copyright © 2013 John Wiley & Sons, Ltd.     

Alterations of the Retinoblastoma a Susceptibility Gene in Chronic Lymphocytic Leukemia

Research in recent years has shown that malignant transformation is a genetic multistep process. This holds true not only for in-vitro model systems, but has also been elegantly shown in-vivo, as in colorectal cancer. Chronic lymphocytic leukemia (CLL) is the most frequent leukemia in Western countries and occurs mainly in elderly patients, suggesting that in this form of leukemia, cumulative molecular lesions may be necessary for transformation. However, the molecular background is unknown in most cases. Cytogenetic aberrations may be used as markers for genes, involved in the process of malignant transformation. In CLL, the most frequently observed structural cytogenetic lesion is a deletion/translocation involving the long arm of chromosome 13, a region where the retinoblastoma susceptibility gene (Rb-gene) has been mapped (13q14). Many groups have studied the question as to whether alterations of the Rb-gene play a causal role in the pathogenesis of CLL., This review deals with recent data indicating that i) the Rb-gene may be altered in a minority of CLL cases, and ii) there may be another gene localized on chromosome 13q14 that may be important in the molecular biology of CLL.     

Genetic alterations in esophageal cancer and their relevance to etiology and pathogenesis: A review

Cancer of the esophagus exists in 2 main forms with different etiological and pathological characteristics—squamous cell carcinoma (SCC) and adenocarcinoma (ADC). This review focuses on the occurrence of genetic alterations in SSC and ADC of the esophagus and on their possible implications for the elucidation of the etiology and pathogenesis of these cancers. The most common alterations found in esophageal cancers include allelic losses at chromosomes 3p, 5q, 9p, 9q, 13q, 17p, 17q and 18q, as well as mutations of p53 (mostly missense). Rb (deletions), cyclin DI (amplifications) and c-myc (amplifications). The sequence of occurrence of these alterations with respect to histopathological tumor progression is discussed. Our findings underscore the different etiology and pathogenesis of SCC vs. ADC and suggest that the genetic alterations observed may represent molecular fingerprints of critical risk involved in the development of these 2 cancers. © 1996 Wiley-Liss, Inc.     

New insights into the pathogenesis of chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL), an incurable disease of the elderly, stands out as unique among the malignancies derived from mature B lymphocytes. The histology, immunophenotype, immunoglobulin variable region (IgV) gene somatic hypermutation status, and the pattern of genetic alterations of the tumor cells are markedly distinct from that of any other B-cell tumor. Most notably, CLL cases can have somatically mutated as well as unmutated IgV genes which largely correlate with a favorable and unfavorable clinical prognosis, respectively. Moreover, recent evidence suggests that 6% of the normal elderly population develops a monoclonal B-cell lymphocytosis (MBL) that appears as the precursor to CLL in 1-2% of cases. Over the last decade, global gene expression profile analysis was instrumental in defining CLL as a malignancy originating from the oncogenic transformation of a common cellular precursor that resembles an antigen-experienced B cell. These findings were complemented by the realization that all CLL, independent of their IgV gene somatic mutation status, express B-cell receptors (BCRs) that show evidence of antigen-experience. Indeed, the BCRs of CLL cases among different individuals can be similar to the extent that one was able to define subsets of stereotyped receptors based on the homology in the antigen-binding regions. Together, these observations strongly support the notion that antigen plays a critical role in CLL pathogenesis. This role is complemented by genetic alterations that, analogous to most cancer types, represent the initiating pathogenetic event. In fact, CLL cases display recurrent genetic aberrations including trisomy 12 and monoallelic or biallelic deletion/inactivation of chromosomal regions 17p, 11q and 13q14. However, virtually all CLL cases lack balanced reciprocal chromosomal translocations, the genetic hallmark of germinal center (GC)-derived lymphomas. The most frequent genetic aberration in CLL, deletion of chromosomal region 13q14, was recently shown to have a specific role in CLL pathogenesis. This region encodes a tumor suppressor locus comprising a microRNA cluster embedded in a long sterile RNA gene, whose deletion in the mouse leads to lymphoproliferative syndromes recapitulating the human CLL-associated spectrum, including MBL, CLL and B-cell non-Hodgkin lymphoma (B-NHL). This review will focus on the cellular origin of CLL, its relationship to the mechanisms of generating CLL-associated genetic lesions and on the role of the 13q14 deletion in CLL pathogenesis as emerging from the analysis of a newly generated mouse model.     

Detection of 14q32.33 translocation and t(11;14) in interphase nuclei of chronic B-cell leukemia/lymphomas by in situ hybridization

Abnormalities of chromosome 14 involving band q32.33 are among the most commonly observed cytogenetic alterations in B-cell malignancies. To assess the incidence and pathogenetic implications of 14q32.33 translocation in chronic B-cell leukemia/lymphomas, we performed fluorescence in situ hybridization (FISH) analysis with variable region (V_H) and gamma constant region (Cγ) gene probes in 37 patients with these disorders. Chromosome 14q32.33 translocation was detected in 2 of 18 patients with chronic lymphocytic leukemia (CLL), 1 of 2 with CLL of mixed cell types (CLL/PL), 1 of 2 with pro-lymphocytic leukemia (PLL), 5 of 6 with leukemic mantle-cell lymphoma (MCL), 2 of 7 with splenic B-cell leukemia/lymphoma of possible marginal zone origin (SBLL) and 2 with leukemic follicular lymphoma (FL). To further characterize 14q32.33 translocations in these patients, we developed a new procedure using double-color FISH with PRAD1, BCL2, V_H and Cγ gene probes. Chromosome t(11;14) was detected in 1 patient with CLL/PL, 1 with PLL and 5 with MCL. Chromosome t(14;18) was detected in 2 patients with FL. In a PLL patient with t(11;14), the cosmid CPP29 containing the PRAD1 gene and its 5′-flanking region split and co-localized with both Cγ and V_H gene probes, thus spanning the breakpoint. In CLL and SBLL patients, donor chromosomes were other than chromosomes 2, 11, 18 and 19, suggesting the involvement of a novel oncogene(s) in the pathogenesis of these diseases. Interphase FISH rapidly detected 14q32.33 translocation, t(11;14) and t(14;18) in B-cell malignancies with low mitotic activity at the single-cell level, facilitating the correlation of the molecular features of these translocations with clinical characteristics. Int. J. Cancer 72:31–38, 1997. © 1997 Wiley-Liss Inc.     

Richter syndrome: molecular insights and clinical perspectives

Richter syndrome (RS) represents the clinico‐pathologic transformation of chronic lymphocytic leukaemia (CLL) to an aggressive lymphoma, most commonly diffuse large B‐cell lymphoma (DLBCL). The clinical definition of RS is heterogeneous, and encompasses at least two biologically different conditions: (i) CLL transformation to a clonally related DLBCL, that accounts for the majority of cases; (ii) development of a DLBCL unrelated to the CLL clone. In clonally related RS, the pathogenetic link between the CLL and the DLBCL phases is substantiated by the acquisition of novel molecular lesions at the time of clinico‐pathologic transformation. RS is not a rare event in the natural history of CLL, since the cumulative incidence of RS at 10 years exceeds 10%. Prompt recognition of RS is known to be clinically useful, and may be favoured by close monitoring of CLL patients harbouring clinical and/or biological risk factors of RS development. Conventional risk factors that are independent predictors of RS development at the time of CLL diagnosis include: (i) expression of CD38; (ii) absence of del13q14 and (iii) lymph node size ≥3 cm. Other risk factors of RS development include CD38 genotype and usage of specific immunoglobulin variable genes. The molecular pathogenesis of RS has been elucidated to a certain extent. Acquisition of TP53 mutations and/or 17p13 deletion is a frequent molecular event in RS, as it is in other types of transformation from indolent to aggressive B‐cell malignancies. Additional molecular alterations are being revealed by genome wide studies. Once that transformation has occurred, RS prognosis may be predicted by the RS score, based on performance status, LDH, platelet count, tumour size and number of prior therapies. Depending on patient's age and RS score, the therapeutic options for RS may range from conventional immunochemotherapy to allogeneic bone marrow transplantation. Copyright © 2009 John Wiley & Sons, Ltd.     

Genomic profiling of Richter's syndrome: recurrent lesions and differences with de novo diffuse large B‐cell lymphomas

Richter's syndrome (RS) represents the transformation of chronic lymphocytic leukaemia (CLL) to aggressive lymphoma and is mostly represented by diffuse large B‐cell lymphoma (DLBCL), with a post‐germinal centre (GC) phenotype, clonally related to the pre‐existing CLL. RS has a very poor prognosis and its pathogenetic mechanisms are poorly understood. In order to gain additional hints in RS pathogenesis, we performed a genome‐wide DNA profiling study of 13 RS phases and eight matched CLL phases using the Affymetrix Human Mapping 250K NspI SNP arrays. Individual genomic profiles were heterogeneous, with no individual lesions occurring in more than half of the cases. However, several observations suggest that MYC pathway might be involved in RS. The 13q13.3‐qter region containing MIRHG1 (MIR‐17‐92), a cluster of microRNA interacting with c‐MYC, was acquired at the time of transformation. The 13q gain was coupled with the gain of c‐MYC and loss of TP53. Translocation of c‐MYC was acquired at transformation in a fraction of cases and this event appeared mutually exclusive with gain of MIRHG1. MYCN, a c‐MYC homologue, was also recurrently gained. By comparing RS with 48 de novo DLBCL, RS presented a significantly lower prevalence of deletions affecting the PRDM1 and TNFAIP3, genes on 6q, known to be associated with a post‐GC phenotype. In conclusion, the genomic profile of RS seems to differ from what observed in de novo DLBCL and in other transformed DLBCL. Genomic lesions occurring in RS are heterogeneous suggesting the existence of different RS subsets, possibly due to different transforming mechanisms. A deregulation of MYC pathway might represent one of the main transformation events in the pathogenesis of a subset of RS clonally related to the previous CLL. Copyright © 2009 John Wiley & Sons, Ltd.     

Clinical heterogeneity of de novo 11q deletion chronic lymphocytic leukaemia: prognostic relevance of extent of 11q deleted nuclei inside leukemic clone

Deletion on the long arm of chromosome 11 occurs in 5–20% of chronic lymphocytic leukaemia (CLL) patients. We analysed clinical–biological characteristics of 131 CLL patients carrying 11q deletion documented before therapy (de novo 11q deleted CLL). De novo 11q deleted CLL were characterized by high frequencies of unmutated immunoglobulin variable heavy genes, multiple fluorescence in situ hybridization aberrations and lymph node involvement. Factors significantly associated with shorter time to first treatment (TTFT) were advanced Binet stages, high white blood cell count, increased β₂‐microglobulin levels, 17p in addition, splenomegaly and more extensive lymphadenopathy. We found that patients with <25% 11q deleted nuclei (n = 22) experienced longer TTFT compared with patients with ≥25% 11q deleted nuclei (n = 87; median TTFT, 40 vs. 14 months, p = 0.011) and also showed better response to treatments (complete response, 50% vs. 21%, p = 0.016). The variables identified by multivariate analysis as independently associated with reduced TTFT were advanced Binet stages [hazard ratio (HR) 4.69; p < 0.001] and ≥25% 11q deleted nuclei (HR 4.73; p = 0.004). De novo 11q deleted CLLs exhibit variable clinical outcome. The percentage of deleted nuclei inside leukemic clone should be included in the prognostic definition of therapy‐naïve 11q deleted CLL patients. Copyright © 2012 John Wiley & Sons, Ltd.     

Night shift work and chronic lymphocytic leukemia in the MCC‐Spain case–control study

Chronic lymphocytic leukemia (CLL) has few known modifiable risk factors. Recently, circadian disruption has been proposed as a potential contributor to lymphoid neoplasms' etiology. Serum melatonin levels have been found to be significantly lower in CLL subjects compared with healthy controls, and also, CLL prognosis has been related to alterations in the circadian molecular signaling. We performed the first investigation of an association between night shift work and CLL in 321 incident CLL cases and 1728 population‐based controls in five areas of Spain. Participants were interviewed face‐to‐face by trained interviewers to collect information on sociodemographic factors, familial, medical and occupational history, including work shifts and other lifestyle factors. We used logistic regression models adjusted for potential confounders to estimate odds ratios (OR) and 95% confidence intervals (CI). Seventy‐nine cases (25%) and 339 controls (20%) had performed night work. Overall, working in night shifts was not associated with CLL (OR = 1.06; 95% CI = 0.78–1.45, compared with day work). However, long‐term night shift (>20 years) was positively associated with CLL (OR_{(tertile 3 vs. day‐work)} = 1.77; 95% = 1.14–2.74), although no linear trend was observed (P trend = 0.18). This association was observed among those with rotating (OR_{(tertile 3 vs. day‐work)} = 2.29; 95% CI = 1.33–3.92; P trend = 0.07), but not permanent night shifts (OR_{(tertile 3 vs. day‐work)} = 1.16; 95% CI = 0.60–2.25; P trend = 0.86). The association between CLL and long‐term rotating night shift warrants further investigation.     

Single-cell genetic analysis of clonal dynamics in colorectal adenomas indicates CDX2 gain as a predictor of recurrence

Colorectal adenomas are common precancerous lesions with the potential for malignant transformation to colorectal adenocarcinoma. Endoscopic polypectomy provides an opportunity for cancer prevention; however, recurrence rates are high. We collected formalin-fixed paraffin-embedded tissue of 15 primary adenomas with recurrence, 15 adenomas without recurrence, and 14 matched pair samples (primary adenoma and the corresponding recurrent adenoma). The samples were analysed by array-comparative genomic hybridisation (aCGH) and single-cell multiplex interphase fluorescence in situ hybridisation (miFISH) to understand clonal evolution, to examine the dynamics of copy number alterations (CNAs) and to identify molecular markers for recurrence prediction. The miFISH probe panel consisted of 14 colorectal carcinogenesis-relevant genes (COX2, PIK3CA, APC, CLIC1, EGFR, MYC, CCND1, CDX2, CDH1, TP53, HER2, SMAD7, SMAD4 and ZNF217), and a centromere probe (CEP10). The aCGH analysis confirmed the genetic landscape typical for colorectal tumorigenesis, that is, CNAs of chromosomes 7, 13q, 18 and 20q. Focal aberrations (≤10 Mbp) were mapped to chromosome bands 6p22.1-p21.33 (33.3%), 7q22.1 (31.4%) and 16q21 (29.4%). MiFISH detected gains of EGFR (23.6%), CDX2 (21.8%) and ZNF217 (18.2%). Most adenomas exhibited a major clone population which was accompanied by multiple smaller clone populations. Gains of CDX2 were exclusively seen in primary adenomas with recurrence (25%) compared to primary adenomas without recurrence (0%). Generation of phylogenetic trees for matched pair samples revealed four distinct patterns of clonal dynamics. In conclusion, adenoma development and recurrence are complex genetic processes driven by multiple CNAs whose evaluations by miFISH, with emphasis on CDX2, might serve as a predictor of recurrence.     

Chromosomal imbalances in familial chronic lymphocytic leukaemia: a comparative genomic hybridisation analysis.

A subset of B cell chronic lymphocytic leukaemia (CLL) is familial. Lack of large families makes it attractive to exploit methods in addition to genetic linkage analysis for the identification of a susceptibility locus. One strategy that can localise regions of the genome that may harbour tumour suppressor genes is to identify regions of chromosomal imbalance using comparative genomic hybridisation (CGH) analysis. We examined 24 familial CLL cases by CGH analysis. Losses that are documented as arising frequently in sporadic CLL were observed at a comparable frequency in familial CLL. However, gains and losses in two regions of the X chromosome - Xp11.2-p21 and Xq21-qter - appear more common in familial CLL than in sporadic CLL. This suggests these regions may harbour a susceptibility locus for CLL. There is also some evidence that chromosome regions 2p12-p14 and 4q11-q21 may harbour predisposition genes.     

Predictive markers and driving factors behind Richter syndrome development

Transformation of chronic lymphocytic leukemia (CLL) to diffuse large B-cell lymphoma (DLBCL) is known as Richter syndrome (RS). In the entire CLL population, the cumulative prevalence of RS development steadily increases at a rate of 1% per year. Considering conventional predictors of CLL, patient subgroups at high risk of developing RS are characterized by the expression of CD38, absence of del13q14, and a lymph node size >3 cm. Novel risk factors for predicting RS development at CLL diagnosis have been recently identified and include: the host genotype of the CD38 locus and of other genes; telomere length of CLL cells; stereotyped B-cell receptor; and usage of specific immunoglobulin variable genes (IGHV4-39). Importantly, although some risk factors predict both CLL progression and transformation to RS, others (CD38 genotype, absence of del13q14, IGHV4-39 usage, stereotyped B-cell receptor) appear to specifically predict RS. The definition of RS encompasses at least two different conditions: DLBCLs that are clonally related to the pre-existing CLL (accounting for most cases), or DLBCL unrelated to the CLL clone. The transition from CLL to clonally related RS is accompanied by the acquisition of novel genetic alterations that may account for the chemorefractoriness of RS. Genome-wide studies that are currently ongoing are important for identifying novel molecular lesions implicated in RS that might represent a suitable target for future therapeutic strategies.     

High resolution deletion mapping reveals frequent allelic losses at the DNA mismatch repair loci hMLH1 and hMSH3 in non-small cell lung cancer

To study the involvement of DNA mismatch repair genes in non-small cell lung cancer, matched normal and tumoral DNA samples from 31 patients were analyzed for both LOH and microsatellite instability with 34 markers at or linked to hMLH1(3p21),hMSH2(2p16), hMSH3(5q11-q13),hMSH6(2p16), hPMS1(2q32), and hPMS2 (7p22) loci. Chromosomal regions 3p21 and 5q11-q13 were found to be hemizygously deleted in 55% and 42% of the patients, respectively. Sixty five percent of the patients deleted at hMLH1 were also deleted at hMSH3. The shortest regions of overlap for 3p21 and 5q11-q13 deletions delimited by D3S1561/D3S1612 and D5S2107/D5S624, respectively, were restricted to genetic distances of only 1 cM. Currently, the hMLH1 (3p21) and hMSH3 (5q11-q13) genes are the only known candidates located within these regions. The mutational analysis of hMLH1 and hMSH3 in hemizygously deleted patients led to the detection of 2 new polymorphisms in hMSH3. The consequence of these allelic losses remains unclear, but the lack of inactivating mutation might explain that replication error, the hallmark of mismatch repair genes inactivation in cancer cells, was quasi-absent in tumors. We suggest that hMLH1 and hMSH3 genes could be involved in lung tumorigenesis through dosage effect in cellular functions other than replication error correction. Int. J. Cancer 77:173–180, 1998. © 1998 Wiley-Liss, Inc.     

Acute myeloblastic leukaemia with alternations of MLL proto-oncogene protein (11q23/MLL+ AML)

One of the most common chromosomal breakpoint regions in acute myeloid leukaemia is the chromosome band 11q23. The analysis of this region led to the discovery of the extremely promiscuous MLL gene, in which more than 60 MLL translocation partner genes have been described. Among the most frequent are t(9;11)(p21-22;q23)/MLL-AF9, t(10; 11)(p13; q23)/MLL-AF10, t(11;19)(q23;p13)/MLL-ELL, ENL and t(6;11)(q27;q23)/MLL-AF6. The presented work provides an overview of the molecular mechanisms by means of which MLL proto-oncogene can be converted into oncogene. Genetic alternations of the MLL Proto-Oncogene Protein besides translocation are also represented by complex chromosomal rearrangements, deletions, insertions, partial tandem duplications, amplifications and gains. These genetic alterations are described in the work from the diagnostic and prognostic point of view. Abnormalities of the MLL ProtoOncogene Protein are usually connected with bad prognosis. For that reason, in oncological practice, particular attention is paid to introducing new genetic methods for their identification. The above work gives well arranged information about different types of genetic tests and their outcomes, which can help oncologists in predicting the prognosis, in minimal residual disease monitoring and in modifying oncological patient treatment.     

Contribution of comparative genomic hybridization and fluorescence in situ hybridization to the detection of chromosomal abnormalities in B-cell chronic lymphocytic leukemia.

BACKGROUND: B-chronic lymphocytic leukemia (B-CLL), the most common type of leukemia in Western Europe and the United States, is characterized by clonal chromosomal abnormalities detected in almost half of the studied patients. The precise determination of chromosomal changes helps to indicate the prognosis and to understand the pathogenesis of CLL. METHODS AND PATIENTS: We applied conventional cytogenetics (CC), FISH and comparative genomic hybridization (CGH) to the investigation of clonal abnormalities in 88 B-CLL patients at the time of diagnosis. RESULTS: By using CC of bone marrow cells without any stimulation, non-random chromosomal changes were found in 17 (19%) of 88 patients.The employment of FISH and CGH revealed chromosomal changes in additional 33 patients, thus increasing the detection rate of chromosomal abnormalities to 57%. The most common abnormalities detected in our patients included deletions of 13q in 16 cases (18%), followed by trisomy of chromosome 12 in 12 patients (13%), deletions of 11q in 10 patients (11%) and deletions of 17p in 10 patients (11%). A statistically significant correlation between higher disease activity and the presence of deletions 11q and 17p was observed. CONCLUSION: The addition of FISH and CGH to CC in 88 B-CLL patients improved the detection of clonal chromosomal changes from 19 to 57%. The most frequent chromosomal change was deletion of 13q14 (18%). Deletions of 11q23 and 17p13 were found in patients with higher clinical disease activity. Our results underline the importance of employing FISH and CGH techniques in CLL patients. CC without any stimulation has a low detection rate and is not suggested for detection of chromosomal changes in CLL.