Significance Of Chromosomal Abnormalities Research Articles

Complex cytogenetic research of cryptic chromosomal aberrations in patients with multiple myeloma

Background . Multiple myeloma (MM) is a malignant lymphoproliferative B-cell disease characterization by clonal proliferation of plasma cells in the bone marrow and beyond its borders. Currently, a wide range of cytogenetic anomalies and molecular-biological parameters are studied as prognostic factors.Objective: a comparative study of the frequency, features and clinical significance of chromosomal abnormalities in MM by conventional cytogenetic and fluorescent in situ hybridization (FISH) methods.Materials and methods . 77 patients with MM, which admitted in N.N. Blokhin National Medical Research Center of Oncology, were included in the study from 2016 to 2017.Results . Chromosomal alterations were detected only in one case (1/77) by conventional cytogenetic method G-banding. However cytogenetic aberrations were revealed in 26 % of cases (20/77) using FISH. Deletions of different regions of chromosomes, indicating the possible presence of a hypodiploid clone or loss of some regions, were found in one patient in the second FISH analysis after 6 months. In the cohort of patients with chromosomal abnormalities (n = 20) a partial trisomy 11q, a deletion of the region q32 of the chromosome 14, a translocation t(4;14)(p16;q32) and IGHV gene rearrangement were determined in 30 % (6/20) as sole anomalies. Two or more cytogenetic aberrations were identified in the remaining 14 patients. Our study confirms that chromosomal abnormalities are more likely detected at later stages of MM (IA и IIA – 0 %, IIIA и IIIВ – 27 and 47 % respectively).Conclusion . FISH allows to detect chromosomal changes in tumor plasma cells regardless of the mitosis phase. In MM, it becomes particularly important in connection with low proliferative activity of plasma cells. Additionally, in the fourth of MM patients in the study submicroscopic chromosomal aberrations were discovered using FISH. The improvement of the probe panel and the widespread use of locus specific FISH don’t replace G-banding that allows to see damages of all chromosomes at once.

Microarray analysis reveals abnormal chromosomal complements in over 70% of 14 normally developing human embryos

What are the aneuploidy rates and incidence of mosaicism in good-quality human preimplantation embryos. High-level mosaicism and structural aberrations are not restricted to arrested or poorly developing embryos but are also common in good-quality IVF embryos. Humans, compared with other mammals, have a poor fertility rate, and even IVF treatments have a relatively low success rate. It is known that human gametes and early preimplantation embryos carry chromosomal abnormalities that are thought to lower their developmental potential. The embryos studied came from nine young (age <35 years old) IVF patients and were part of a cohort of embryos that all resulted in healthy births. These 14 embryos inseminated by ICSI and cryopreserved on Day 2 of development were thawed, cultured overnight and allowed to succumb by being left at room temperature for 24 h. Following removal of the zona pellucida, blastomeres were disaggregated and collected. There were 91 single blastomeres collected and amplified by multiple displacement amplification. Array-comparative genomic hybridization was performed on the amplified DNA. Array-data were normalized and aneuploidy was detected by the circular binary segmentation method. The good-quality embryos exhibited high rates of aneuploidy, 10 of 14 (71.4%) of the embryos being mosaic. While none of the embryos had the same aneuploidy pattern in all cells, 4 of 14 (28.6%) were uniformly diploid. Of the 70 analysed blastomeres, 55.7% were diploid and 44.3% had chromosomal abnormalities, while 29% of the abnormal cells carried structural aberrations. Finding such a high rate of aneuploidy and mosaicism in excellent quality embryos from cycles with a high implantation rate warrants further research on the origin and significance of chromosomal abnormalities in human preimplantation embryos. This research was supported by the Instituut voor de aanmoediging van innovatie door Wetenschap en Technologie in Vlaanderen (IWT-Vlaanderen). A.M. is a PhD student at the IWT-Vlaanderen. C.S. is a postdoctoral fellow at the FWO Vlaanderen. There are no competing interests.

Rapid testing versus karyotyping in Down's syndrome screening: cost-effectiveness and detection of clinically significant chromosome abnormalities.

In all, 80% of antenatal karyotypes are generated by Down's syndrome screening programmes (DSSP). After a positive screening, women are offered prenatal foetus karyotyping, the gold standard. Reliable molecular methods for rapid aneuploidy diagnosis (RAD: fluorescence in situ hybridization (FISH) and quantitative fluorescence PCR (QF-PCR)) can detect common aneuploidies, and are faster and less expensive than karyotyping.In the UK, RAD is recommended as a standalone approach in DSSP, whereas the US guidelines recommend that RAD be followed up by karyotyping. A cost-effectiveness (CE) analysis of RAD in various DSSP is lacking. There is a debate over the significance of chromosome abnormalities (CA) detected with karyotyping but not using RAD. Our objectives were to compare the CE of RAD versus karyotyping, to evaluate the clinically significant missed CA and to determine the impact of detecting the missed CA. We performed computer simulations to compare six screening options followed by FISH, PCR or karyotyping using a population of 110 948 pregnancies. Among the safer screening strategies, the most cost-effective strategy was contingent screening with QF-PCR (CE ratio of $24 084 per Down's syndrome (DS) detected). Using karyotyping, the CE ratio increased to $27 898. QF-PCR missed only six clinically significant CA of which only one was expected to confer a high risk of an abnormal outcome. The incremental CE ratio (ICER) to find the CA missed by RAD was $66 608 per CA. These costs are much higher than those involved for detecting DS cases. As the DSSP are mainly designed for DS detection, it may be relevant to question the additional costs of karyotyping.

Age has a profound effect on the incidence and significance of chromosome abnormalities in myeloma

A simple high throughput micro-fluorescence in situ hybridisation technique (FISH) was used to detect chromosome 13 deletions (delta13), immunoglobulin heavy chain (IgH) rearrangements, t(11;14)(q13;q32), t(4;14)(p16;q32), t(14;16)(q23;q32), p53 loss, and numerical changes of chromosomes 3, 6, 7, 9, 10, 11 and 17 in 228 cases of multiple myeloma (MM), including 33 asymptomatic/smouldering MM (SMM). The patients were not part of a clinical trial and were from 30 different hospitals. In all, 98.4% of cases were abnormal, with 43% having IgH rearrangements and 42% Delta13. The low incidence of IgH rearrangements was due to a decrease in this finding with age (P = 0.001) and the relatively high proportion of elderly patients in our study population (41% >70 years old). The incidence of specific IgH translocations was t(4;14) 11%, t(11;14) 16% and t(14;16) 3%. Univariate statistical testing showed delta13 (P = 0.002), and t(14;16) (P = 0.005) to be associated with shorter survival. This effect was exaggerated for patient's aged 70 years or under but no effect on survival was seen for those over 70 years. In younger patients t(4;14) (P = 0.044) and p53 deletion (P < 0.001) were also significant poor prognostic indicators. Multivariate analysis showed delta13 and t(14;16) to be independent prognostic variables when considered with age and clinical parameters.

The detection and significance of chromosomal abnormalities in childhood acute lymphoblastic leukaemia

In childhood acute lymphoblastic leukaemia (ALL), cytogenetics plays an essential role in diagnosis and prediction of outcome. Conventional cytogenetic analysis, complemented by fluorescence in situ hybridization (FISH), is highly effective in the accurate detection of chromosomal abnormalities. For the precise identification of specific genetic changes, molecular techniques may be applied. Chromosomal changes in ALL may be of structural or numerical type. A large number of established structural chromosomal rearrangements have now been described for which the genetic alterations and effect on prognosis are well known. These include t(9;22)(q34;q11) and BCR/ABL, rearrangements of 11q23 involving MLL, t(12;21)(p13;q22) with the ETV6/AML1 fusion, t(1;19)(q23;p13) with E2A/PBX1, t(8;14)(q24;q32) and the immunoglobulin genes. Genetic changes associated with T ALL are also known, although their effect on outcome is less pronounced. Rare chromosomal abnormalities are continually being discovered in small patient subgroups leading to the identification of new ALL associated genetic changes. Alterations in chromosome number have a strong impact on outcome in childhood ALL. The association of a high hyperdiploid karyotype (51–65 chromosomes) with a good prognosis has been known for more than 20 years. Conversely, the loss of chromosomes in the near-haploid group (23–28 chromosomes) indicates a poor outcome. New methods of cancer classification involving gene expression profiling may eventually supercede cytogenetic analysis in the diagnosis and prediction of outcome in leukaemia. It is more likely that they will be used in a complementary approach alongside cytogenetic, FISH and molecular analysis to guide patient management in childhood ALL.

Diagnostic and prognostic significance of chromosome abnormalities in childhood acute lymphoblastic leukemia.

Current intensive chemotherapies cure about 70% of the children with ALL. On the other hand a significant number of the children are not cured despite intensive treatment. At the same time some highly curable patients are treated too intensively and suffer from unnecessary side effects of the chemo- and radiotherapy applied. In order to further improve the therapeutic results in this disease, we have to distinguish between the cases with a better and a worse prognosis. The initial karyotype (both numerical and structural chromosome abnormalities) proved to be one of the most reliable prognostic parameters, leading to the suggestion of developing genotype-specific therapies. Although the prognosis in patients with pseudodiploid karyotype is usually unfavorable, a significantly better prognosis can be observed in those with more than 50 chromosomes. Because the latter patients can achieve remission on a metabolite-based therapy, the toxic effects of more aggressive chemotherapy with anthracyclines and genotoxic agents can be avoided; thus, the reliable and accurate identification of patients with > 50 chromosomes is of particular importance. For this purpose three methods: chromosome analysis, DNA flow cytometry, and fluorescence in situ hybridization can be used. In 1993 it was decided to develop a comprehensive nationwide project in order to perform the initial genetic analysis of all ALL children diagnosed in the hematological/oncological centers of Hungary. Here the data obtained on 187 ALL patients diagnosed in the period from 1993 to 1995 are presented. In about 75% of patients (in 140 of 187) chromosome analysis was performed, in 78 cases (55.7%) successfully. The proportion of patients with abnormal karyotype was 36 of 78 (46.1%), and hyperdiploidy with more than 50 chromosomes was detected in 13 of 78 (16.6%) children. The lower ratio of hyperdiploid cases in our patients as compared to the data in the literature may be due to technical difficulties and the small number of patients studied, but it may reflect real geographic characteristics. Using flow cytometry, seven of 31 patients investigated (22.5%) proved to be hyperdiploid with a DNA index above 1.16. A higher ratio of hyperdiploid patients in this study calls attention to the significance of simultaneous application of the two methods. Taken together, 16 of 80 (20.0%) successfully studied patients proved to be hyperdiploid (> 50 chromosomes and/or DNA index above 1.16). The pattern of chromosome involvement in our study determined by chromosome analysis and/or FISH technique proved also to be different from the data of large international series. In addition to trisomies of chromosomes 4, 6, 10, 14, 17, 18, 21, and X, which are known to be the most frequently involved chromosomes, trisomies of chromosomes 3, 8, 11, and 13 were also observed with a high frequency. Comparison of survival curves of various cytogenetic subgroups showed a significant difference between diploid-pseudodiploid and diploid-hyperdiploid A (with 47-50 chromosomes) subgroups. No favorable prognosis of hyperdiploid patients (> 50 chromosomes) could be proved. Because of the small number of patients studied, prognostic differences of cytogenetic subgroups need further confirmation. The clinical and genetic differences observed, however, call attention to the necessity for further genetic studies of ALL patients in Hungary, because these differences may reflect real geographic characteristics and may be related to different environmental mutagen/carcinogen effects of the given geographic area. It is essential to determine whether or not these differences really exist and if they do to reveal the causes leading to these differences. In our view this is one of the routes by which the therapeutic results in childhood ALL can be further improved simultaneously with the avoidance of early and late toxicity of chemotherapy.

Significance of chromosomal abnormalities in a malignant giant cell tumor of bone

Cytogenetic analysis of a malignant giant cell tumor of the sacrum from a 62-year-old female revealed the following chromosomal complement: 47,XX,−1,−11,+22,del(2)(p22),t(7;7) (p22;q32),+der(1)t(1;11;21)(p32;q13;q22),+der(19)t(19;?)(q13.4;?),der(8)t(8;?)(p11;?),der(7)t(17;?)(p13;?). Metaphase cells with 92–127 chromosomes sharing identical structural abnormalities detected in the near-diploid cells were also observed. Several of these abnormalities have previously been described in the benign giant cell tumors supporting a direct relationship between these benign and malignant neoplastic counterparts.

Cytogenetics and cancer

The significance of chromosome abnormalities in the diagnosis and management of patients with malignant haematol-ogical disorders is well established. Specific abnormalities identify specific varieties of acute and chronic leukaemias and non-Hodgkin’s lymphoma, to the extent that a cytogenetic classification of these diseases may be more useful to the treating clinician than standard morphology. In fact a new classification of acute leukaemia based on combined morphology, immunophenotype and cytogenetic abnormalities has been produced, which is considered a clinically useful refinement of the FAB classification. Such conclusions have been reached because of great improvement in cytogenetic culture and identification techniques over the past 15 years. Similar studies in solid tumours have been hampered because of the relatively low mitotic rate in these malignancies, with the exception of paediatric tumours where abnormalities specific for the tumour variety have already been identified. However improved culture techniques are now allowing the recognition of specific abnormalities in carcinomas. Primary cytogenetic changes, considered to occur very early in the malignant process, have been separated from secondary abnormalities which indicate progression and thus aggression of tumours. Non-random abnormalities have even been found in benign tumours such as lipomas and adenomas. ‘Molecular cytogenetics is adding another parameter to our investigation of all malignancies by the identification of oncogene and growth factor rearrangements and amplifications associated with the structural chromosomal changes.

Chromosome abnormalities in malignant lymphoma: biologic and clinical correlations.

Among the hematologic malignancies, the clinical and biologic significance of chromosome abnormalities have been most extensively studied in the acute leukemias and chronic myelogenous leukemia (CML). Clonal chromosome abnormalities are now identified in essentially all cases of CML and in most cases of acute nonlymphoblastic leukemia (ANLL) and acute lymphoblastic leukemia (ALL). In the acute leukemias, specific chromosome abnormalities have now been correlated with morphology (ANLL), immunologic phenotype (ALL), and various clinical features. In both ANLL and ALL, they have been found to be clinically important as independent risk factors for predicting response to treatment, remission duration, and survival [1–4].

An Interactive Chromosone Scanning System

To the relatively few groups actively engaged in automated chromosome studies, the title of this paper is rather self explanatory because it proposes to address a problem which has become apparent to all of us who have sought to automate cell analysis. The need for human interaction implies that our automated procedures are not error free and require some degree of human verification and correction within the procedure. Indeed this is so. The fact that a problem exists may be attributed to an over-optimistic concept of the capability of machines to duplicate apparently simple human activity. It follows that certainly one purpose of this paper would be to discuss the need for human interaction in automated chromosome analysis and to suggest an approach to the question of where and how interaction should be implemented. However, so that others who may be unfamiliar with automated chromosome analysis can achieve a better understanding, the format of this paper includes a brief overview of human cytogenetics along with an attempt to treat the significance of chromosome abnormalities in terms of the need for population studies. Unfortunately, the justification for automated procedures in cytogenetics has been based upon the need to reduce the labor and tedium involved in large studies without the need for the large studies themselves being clearly established on a cytogenetic basis.

Hypodiploid chromosome pattern in acute leukemia following polycythemia vera.

A man with a 12-year history of polycythemia developed acute leukemia and died at age 81 years. A hypodiploid mode of 43 chromosomes was the predominant cell type in marrow and blood during the leukemic phase. Analyses of cells with 43 chromosomes were consistent and included two marker chromosomes. One of these was a minute chromosome and its relationship to the Philadelphia chromosome was uncertain. The significance of chromosomal abnormalities in the myeloproliferative disorders is discussed.