Complex Karyotypic Abnormalities Research Articles

Telomere length in myelodysplastic syndromes

We have studied telomere length in the bone marrow cells or the granulocyte and lymphocyte cell fractions of 54 patients with myelodysplastic syndromes (MDS) by Southern blot hybridization using the (TTAGGG)4 probe. The average telomere length expressed as the peak telomere repeat array (TRA) in the peripheral blood, or bone marrow samples obtained from a group of 21 healthy age-matched controls (26–89 years old, mean age 55), ranged between 7.5 and 9.5 kb (mean peak TRA 8.6 kb). Twenty-four patients with refractory anemia (RA) were studied; 10/24 (42%) had telomere reduction (<7.5 kb) relative to age-matched controls and the mean peak TRA was 7.5 kb (range 4.0–9.0 kb). Eleven patients with RA with excess blasts (RAEB) were studied; 5/11 (45%) had reduced telomeres relative to age-matched controls and the mean peak TRA was 7.1 kb (range 5.0–9.0 kb). Eighteen patients with MDS in transformation to AML, comprising 15 with RAEB in transformation (RAEBt) and 3 with CMML in transformation (CMMLt), were also studied. Thirteen of eighteen patients (72%) had telomere reduction relative to age-matched controls and the mean peak TRA was 6.1 kb (range 3.5–9.0 kb). Thirty-six patients included in the study had either a normal karyotype or a simple karyotype (1 karyotypic change) and 20/36 (55%) of these had telomere reduction and the mean peak TRA was 7.1 kb (range 4.3–9.0 kb); 8 patients had a complex karyotype (3 or more karyotypic changes) and 5/8 (62%) of these had telomere reduction and the mean peak TRA was 6.1 kb (range 3.5–9.0 kb). We conclude, firstly that there is heterogeneity of telomere length in MDS and that this is observed throughout the spectrum of FAB-subtypes. Secondly, these data show that a marked reduction in telomere length in MDS if often associated with leukemic transformation and with the presence of complex karyotypic abnormalities. Am. J. Hematol. 56:266–271, 1997. © 1997 Wiley-Liss, Inc.

Characteristics of rhabdomyosarcoma cell lines derived from uterine carcinosarcomas

Rhabdomyosarcoma (RMS) is occasionally found in the female genital tract, and mostly appears as one of the heterologous mesenchymal components in uterine carcinosarcoma designated as malignant mixed mullerian tumour (MMMT). We examined the biological properties of a pure rhabdomyosarcoma (RMS) cell line designated FU-MMT-3, which was newly established from a surgical specimen taken from a patient with uterine MMMT. We also evaluated c-myc and MYCN gene amplification in three RMS cell lines (including FU-MMT-3) derived from three MMMTs by Southern blot analysis. FU-MMT-3 cells were propagated continuously for 57 serial passages over a 2-year period in vitro. FU-MMT-3 was able to produce tumours demonstrating pure RMS in athymic nude mice. Cytogenetically, FU-MMT-3 showed a triploidy pattern, with complex karyotypic abnormalities including trisomy of chromosome 8. All three RMS cell lines, including FU-MMT-3, showed amplification of the c-myc gene (approximately fourfold to eightfold), while no cell lines demonstrated MYCN gene amplification. FU-MMT-3 is considered to provide a useful system for the study of the biological behaviour of RMS in MMMTs. Extra copies of chromosome 8 and c-myc gene amplification may be associated with the rhabdomyoblastic differentiation in MMMT.

Genes and chromosomes in chronic B-cell leukemia

Cytogenetic analysis of patients with chronic B-cell leukemia (B-CLL) indicates that 50% have chromosome abnormalities, while fluorescence in situ hybridization (FISH) and molecular techniques reveal an even higher incidence. Trisomy 12 and deletions or translocations of chromosome 13q14 are the most common abnormalities, but in neither case has the gene or genes involved in the abnormalities been identified. Combined FISH and immunophenotyping studies suggest that both abnormalities are secondary events in B-CLL. Other recurring chromosome abnormalities include 6q-, 11q- and 12p-, but the genes involved in these abnormalities have not been identified. Involvement of the BCL1, BCL2, and BCL3 genes has been reported, but the numbers are low and the cases tend to be atypical. Trisomy 12 in association with complex karyotypic abnormalities is associated with a poor prognosis, and FISH studies show a strong correlation between trisomy 12, atypical morphology, and advanced disease. Ten to 15% of patients have mutations of p53 which is associated with advanced disease, resistance to treatment, and poor survival.

Genetic abnormalities in chronic lymphocytic leukemia and their clinical and prognostic implications

Clonal chromosome abnormalities can be detected in approximately 50% of patients with chronic lymphocytic leukemia (CLL). The most common changes are trisomy 12, followed by structural abnormalities of 13q, 11q, 6q, and 14q. By fluorescence in situ hybridization (FISH), these aberrations can be demonstrated even in cases with insufficient mitotic yield or a normal karyotype. The biologic consequences of trisomy 12 are unknown, but a gene dosage effect is suspected and studies on partial trisomy 12 indicate that the region 12q13 to 12q22 might be of particular pathogenetic importance. Trisomy 12 is strongly associated with atypical lymphocyte morphology and seems to be a secondary event in leukemogenesis, as shown by combined immunophenotyping and interphase FISH. Structural abnormalities of 13q frequently involve hetero- and homozygous deletions of a region in 13q14, distal to the retinoblastoma gene, which may be the site of a tumor suppressor gene. In contrast to a normal karyotype or structural changes of 13q, complex karyotypic abnormalities, high percentage of abnormal metaphases, trisomy 12 and structural changes involving the P53 tumor suppressor gene on 17p13 are adverse prognostic indicators. Cytogenetic and molecular findings provide important diagnostic, clinical, and prognostic information which can contribute to treatment decisions and follow-up of CLL patients.

Cytogenetics: An Evolving Role in the Diagnosis and Treatment of Cancer

Conventional cytogenetics has been used for many years in the diagnosis and follow-up of myeloproliferative disorders. Molecular techniques including FISH and gene rearrangements are complementary in the evaluation of myeloproliferative and myelodysplastic disorders. Lymphomas and lymphocytic leukemias have nonrandom cytogenetic patterns that are useful in the clinical diagnosis, prognosis, and therapeutic follow-up. Solid tumors have complex karyotypic and genetic abnormalities, and clinical utilization of conventional cytogenetics and molecular techniques is in the developmental stages of applicability. The benefits of karyotype analysis in myeloproliferative and lymphoproliferative diseases include guidance for diagnostic and therapeutic approaches as well as assessment of minimal residual disease. Conventional cancer cytogenetics and commercially available FISH reagents enhance these applications. Molecular diagnostic techniques are analytically sensitive and specific. The complexities of the function and role of genetic abnormalities in solid tumors present challenges in the choice, interpretation, and application of conventional cytogenetic and molecular data. These challenges offer exciting potential for future advances.

Structural chromosome anomalies in congenital diaphragmatic hernia.

In order to determine the outcome and associated chromosomal and structural anomalies in fetuses diagnosed in utero as having a congenital diaphragmatic hernia, we reviewed 48 consecutive cases referred to our regional Fetal Diagnostic Unit between 1988 and 1995. All babies were delivered in units with appropriate neonatal resuscitation facilities. Thirteen babies [34 per cent of those tested, confidence interval (CI) 19-49 per cent] had karyotypic abnormalities. Three had trisomies but the other nine had more complex karyotypic abnormalities including translocations, deletions, and marker chromosomes. Twenty-one fetuses (44 per cent, CI 30-58 per cent) had additional ultrasound abnormalities which affected the heart in ten cases (21 per cent). Overall, 13 babies survived (27 per cent, CI 14-40 per cent). In babies with normal chromosomes and no additional structural abnormalities the survival rate was 50 per cent (CI 25-75 per cent). Poor outcome was not predicted by early gestation at diagnosis, the hernial contents, or the presence of polyhydramnios. We conclude that parents should be counselled about prognosis with information derived from series of prenatally diagnosed diaphragmatic hernias. The investigations offered should include a detailed ultrasound examination, particularly of the heart, and karyotyping by fetal blood sampling.

TP53 mutations in myelodysplastic syndrome.

Mutations of the TP53 tumor suppressor gene, contributing to the development and progression of a wide variety of human malignancies, are found in some of the patients with myelodysplastic syndromes (MDS). Previous reports revealed that TP53 mutations were found in 0-25% of patients with MDS and are closely associated with a complex abnormal karyotype including such chromosomal losses as -5/5q-, -7/7q- and/or 17p-, which are known to be frequent in therapy-related leukemias. We have also detected TP53 mutation in 10 (14%) of 70 patients with MDS. All of the mutations were detected at the time of diagnosis, which suggest the TP53 mutation may play a role in the development of MDS. Those patients with a TP53 mutation had a poor prognosis regardless of leukemic transformation or not. The reported mutational spectra of TP53 in MDS and ANLL differ from those of colon and lung cancers. Compared with other hematological disorders, the spectrum of TP53 mutations in MDS and ANLL is assumed to be associated with pathogenic exposure to known or unknown carcinogens, as suggested by the chromosomal findings. Further studies are required to clarify the pathogenesis of this heterogenous disease entity.

Acute leukemia with t(10;11)(p11-p15;q13-q23)

We report six patients with acute leukemia characterized by the presence of a t(10;11) (p11-p15;q13-q23), either as sole cytogenetic abnormality (three patients) or as part of a complex abnormal karyotype. The morphologic and cytochemical features of four patients were consistent with FAB-M5A, while two patients presented with FAB-L1 characteristics. By immunophenotyping, myeloid leukemia was diagnosed in five patients, including one patient with FAB-L1 leukemia who typed as terminal transferase (TdT) +, CD7 T-cell antigen + acute myelomonocytic leukemia. Differentiated acute myeloid leukemia (AML) with expression of terminal transferase was found in two of the other cases and monocytic leukemia in two, with co-expression of T-cell antigens in one of them. The second FAB-L1 patient typed as undifferentiated acute lymphocytic leukemia (ALL) expressing myeloid antigens. Serial phenotypic studies in patient 3 during the course of the disease demonstrated a switch from monocytic to lymphoid morphology at the time of first and second relapse, which was paralleled by the appearance of a pre-T ALL immunophenotype with co-expression of the myeloid antigen CD33. These phenotypic changes occurred without apparent alteration in the genotype since t(10;11)(p11.2;q23) remained the only cytogenetic aberration at all stages of the disease. Our observations suggest that the (10;11) variant of 11q aberrations occurs in a bipotential myelomonocytic/T-lymphoid stem cell.

Multiple clonal chromosome aberrations in a case of childhood focal nodular hyperplasia of the liver

A case of focal nodular hyperplasia is described that was accompanied by intense reactive stromal changes giving rise to a pseudosarcomatous appearance. Cytogenetic study revealed complex karyotypic abnormalities including five partially identifiable clonal aberrations and one marker chromosome. The composite karyotype was interpreted as: 45–46,XY,add(4)(q21–25)[24], add(11)(p14)[24],add(19)(p13) [15],der(20)t(1;20)(q25;p12)[31],add(21)(q22)[13],-22[3], +mar[2][cp31]. In addition, quadriradial or complex figures, telomeric associations tas, unidentified ring chromosomes, chromosome breaks, and markers were seen in some cells. Such cytogenetic findings, although suggestive of malignancy, could most likely be related to a nonneoplastic condition, i.e., the unusual florid reactive changes associated with this focal nodular hyperplasia.

Comparative genomic hybridization in acute myeloid leukemia: A comparison with G-banding and chromosome painting

Comparative genomic hybridization (CGH) represents a new technique for global analysis of a whole genome for net loss or gain of chromosome regions. It offers several advantages over alternative techniques. It permits analysis of a whole genome in a single hybridization reaction, it does not require the generation of metaphases from tumor cells, and it only requires very small numbers of tumor cells. Most previous studies have concentrated on the application of CGH to the analysis of chromosome defects associated with solid tumors. In this paper we report the use of CGH to study bone marrow samples from a patient with acute myeloid leukemia and complex karyotypic abnormalities. The results obtained using CGH were compared with G-banding analysis. Both G-banding and CGH detected a 5q deletion, a 7q deletion, additional material derived from 8q, and an HSR on 11q. However, several apparently discrepant results were also obtained. Paints for chromosomes 3, 5, 7, 8, 11, 12, 14, 17, 22, and X were therefore used to resolve these differences. Our results demonstrate that CGH detected chromosome abnormalities associated with acute myeloid leukemia and that CGH provided information that was not obtained by G-banding analysis alone. These data suggest that CGH may prove a useful adjunct to conventional cytogenetic and molecular analysis of hematologic malignancies.

TP53 Mutations Emerge at Early Phase of Myelodysplastic Syndrome and Are Associated With Complex Chromosomal Abnormalities

We examined TP53 mutation in 57 patients with myelodysplastic syndrome (MDS) at either the MDS phase or at the terminal leukemic phase using polymerase chain reaction-mediated single-strand conformation polymorphism (PCR-SSCP) analysis. TP53 mutations within exons 5 through 8 were found in seven patients. All these mutations were detected at the presentation of MDS whether these patients showed leukemic transformation or not. TP53 mutations were frequently found in patients with loss of the short arm of chromosome 17 (17p-) (three of seven patients with 17p-, 43%) and complex karyotypic abnormalities (five of 14, 38%). Among the seven patients with the TP53 mutation, four patients progressed to acute leukemia within 7 months from the diagnosis of MDS, and the remaining three died within 7 months without leukemic transformation. These findings suggest that mutations of the TP53 can be implicated in leukemic transformation and a poor prognosis in MDS.

Genetic changes in ovarian cancer.

The development of cancer is a multistep process involving accumulation of genetic changes which progressively transform normal cells to neoplastic cells. During the last few years, our understanding and knowledge of the genetic changes involved in ovarian carcinogenesis have increased dramatically. In this review I will focus on karyotypic abnormalities in ovarian cancer and will also refer to molecular studies involving alterations in oncogenes and tumour suppressor genes in ovarian tumorigenesis. Cytogenetic analyses have identified two distinct subgroups. Simple karyotypic changes, trisomy 12 being the most common aberration in this group, are recurrently found in well differentiated ovarian carcinomas. Complex karyotypic abnormalities, including predominantly chromosome losses, deletions and unbalanced translocations, are found in moderately and poorly differentiated carcinomas. The bands and regions most commonly involved in structural rearrangements have been, in decreasing order of frequency, 19p13, 1p36, 1q21, 1q23-25, 3p11-13, 6q21, 19q13, 11p13-15, 11q13, 11q23, 12q24, 12p11-13, and 7p13-22. The finding of identical karyotypic and other genetic changes in tumour samples taken from different sites, such as tumours from both ovaries and omental metastases, indicate that ovarian cancer is of unicentric origin with subsequent metastatic spread giving rise to multiple implants. Molecular genetic changes important in ovarian cancer involve both classes of tumor-associated genes: RAS activation is generally not observed in ovarian cancer. Alterations of MYC1, ERBB2, AKT2, TP53 has been described in some ovarian carcinomas. The temporal relationship of these mutations, i.e. early or late events in ovarian carcinogenesis, remains to be determined.

Cytogenetic and molecular abnormalitiesin chronic lymphocytic leukaemia

Genetic abnormalities are found in 50% of cases of chronic lymphocytic leukaemia (CLL) by cytogenetic analysis and in a higher percentage of patients using molecular techniques. The commonest cytogenetic abnormalities are trisomy 12 and deletions or translocations of the long arm of chromosome 13 usually involving band q14. The genetic consequences of trisomy 12 are unknown but structural abnormalities of chromosome 13q14 frequently involve hetero or homozygous loss of a region distal to the retinoblastoma gene which may be the site of a tumour suppressor gene. Trisomy 12 or loss of one copy of the retinoblastoma gene have been detected by fluorescent in situ hybridisation (FISH) in interphase cells of patients with a normal karyotype. By combining FISH with immunophenotyping, it has been found that trisomy 12 occurs in only 30 to 40% of the malignant clone, suggesting that it is a secondary event in leukaemogenesis. Trisomy 12 is strongly associated with atypical lymphocyte morphology in patients with otherwise typical CLL. Complex karyotypic abnormalities, a high percentage of abnormal metaphases and trisomy 12 but not structural abnormalities of chromosome 13 are associated with a poor prognosis at all stages of the disease. Mutations or deletions of the P53 gene are found in 10 to 15% of patients with advanced CLL and correlate with resistance to treatment and poor survival.

Trisomy 7 in nonneoplastic cells

The somatic mutation theory of tumorigenesis states that mutations are necessary for tumor development. On the other hand, acquired, clonal chromosomal alterations are occasionally detected in otherwise normal, nonneoplastic cells--for example, loss of sex chromosomes occurs in bone marrow cells and lymphocytes in elderly individuals--and it is therefore evident that not all mutations are by themselves sufficient for neoplasia to occur. Thus, the finding of an acquired, clonal chromosomal abnormality does not constitute proof that a lesion is neoplastic. Trisomy 7 has, as the sole clonal chromosomal aberrations, been reported in a wide variety of epithelial tumor types but also in some mesenchymal and neurogenic neoplasms. It has been suggested to be a primary, i.e., tumor-initiating, abnormality in tumors of the bladder, brain, colon, kidney, lung, ovary, prostate, and thyroid. But data from cytogenetic studies of solid tumors, macroscopically normal tissue in the proximity of solid tumors, and nonneoplastic lesions now question the importance of a solitary +7 as a neoplasia-associated change. Most solid tumors in which trisomy 7 has been found as the sole change in one clone have also displayed other, cytogenetically unrelated, clones with complex karyotypic abnormalities. Such karyotypic differences among coexisting clones could indicate that the neoplasm is polyclonal, that the cytogenetically disparate clones have emerged during tumor progression from one original clone carrying submicroscopic genomic changes only, or that the clone with +7 does not represent the tumor parenchyma. The latter interpretation is supported by the finding of cells with trisomy 7 in macroscopically normal tissue outside tumors of the brain, kidney, and lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Complex karyotypic abnormalities including t(8;22) in a patient with chronic lymphocytic leukemia

The case of a 49-year-old Chinese man with B-cell chronic lymphocytic leukemia (B-CLL) is presented. Complex karyotypic abnormalities comprising t(8;22)(q24;q11), trisomy 7, a deletion of 11q, and two small marker chromosomes were observed in PWM-stimulated cultures of his peripheral blood cells. To our knowledge, this is the first report of a t(8;22) in CLL.

Acute myelogenous leukemia (AML) and diabetes insipidus (DI): Further association with monosomy 7

Diabetes insipidus (DI) is a rare complication of acute myelogenous leukemia (AML). Five of the six such cases described in the literature who had banded chromosomal studies performed had monosomy 7 and the sixth patient had del(7)(q22). A further case of AML complicated by DI in whom banded chromosomal studies revealed a complex karyotypic abnormality, including monosomy 7, is reported. The association between monosomy 7 and DI in AML appears specific but the reason for this association remains unclear.

Near-triploid myeloblastic transformation of chronic myeloid leukemia with bizarre blast morphology

We describe a case of chronic myeloid leukemia (CML) in myeloblastic transformation in which near-triploidy with complex karyotypic abnormalities occurred together with unusual blast morphology. A review of the literature shows that near-triploidy is extremely unusual in blastic transformation (BT) of CML.

Prognostic factors in stage AO B‐cell chronic lymphocytic leukaemia

85 patients presenting to a single centre with stage AO B-cell chronic lymphocytic leukaemia (B-CLL) have been studied. The duration of follow-up has ranged from a minimum of 1 year to a maximum of 18 years with a mean of 6 years. 14 patients have had progressive disease and 23 patients have died, of whom nine had CLL-related deaths. We assessed the prognostic significance of the following parameters: age at presentation, sex, haemoglobin concentration, initial lymphocyte count, surface membrane phenotype, serum immunoglobulin levels at presentation and karyotype. None of these factors were predictive of survival, but there was a correlation between initial lymphocyte count, surface immunoglobulin MD lambda phenotype, and complex karyotypic abnormalities and disease progression. Two patients with a complex karyotype have been followed for more than 5 years without evidence of progression.

Malignant fibrous histiocytomas with a 19p+ marker chromosome have increased relapse rate

Malignant fibrous histiocytomas (MFH) often have complex karyotypic abnormalities. Recently, we described a 19p+ marker chromosome in 9 of 22 MFH. Other recurrent karyotypic features have been telomeric associations, ring chromosomes, and structural rearrangements of chromosomal bands 1q11, 3p12, and 11p11. After a median follow-up time of 18 months, distant metastases and/or local recurrence have occurred in 8 of the 9 patients with 19p+ markers but in only 4 of the 13 patients without. The only other cytogenetic parameter that seemed to affect relapse tendency was the presence of ring markers: relapse has occurred in 2 of 8 patients with unidentifiable supernumerary ring marker chromosomes compared to 10 of 14 patients without. No differences in relapse frequency were apparent for tumors belonging to the other cytogenetic subgroups. It thus appears that 19p+ marker chromosomes in MFH signal an increased relapse risk whereas the finding of ring markers indicates a reduced relapse risk.

Correlation of chromosome abnormalities with laboratory features and clinical course in B‐cell chronic lymphocytic leukaemia

141 patients with B-cell chronic lymphocytic leukaemia (B-CLL) have been studied for a minimum of 12 months and a maximum of 25 years. 30 of 133 patients (32.5%) had greater than 10% FMC7 positive peripheral blood lymphocytes and 19 of 131 patients (14.5%) had a serum or urinary paraprotein. At presentation 88 patients were stage A0, 18 A1, 18 A2, 11 B and six C. 44 (31%) had progressive disease and 42 (30%) died during the study period. 63 patients had a normal karyotype, 75 a clonal abnormality and in three no metaphases were obtained. The finding of a complex karyotypic abnormality was significantly associated with lambda surface phenotype (P less than 0.01), the presence of greater than 10% FMC7 positive cells (P less than 0.025), and the presence of a paraprotein (P = 0.025). Patients whose leukaemic cells had a complex karyotype and those with structural abnormalities of chromosomes 14 and 6 required treatment earlier than those with a normal karyotype.