Cytogenetic analysis in 941 consecutive patients with haematologic disorders

Genetic testing in the myelodysplastic syndromes: molecular insights into hematologic diversity

The myelodysplastic syndromes (MDS) are associated with a diverse set of acquired somatic genetic abnormalities. Bone marrow karyotyping provides important diagnostic and prognostic information and should be attempted in all patients who are suspected of having MDS. Fluorescent in situ hybridization (FISH) studies on blood or marrow may also be valuable in selected cases, such as patients who may have 5q- syndrome or those who have undergone hematopoletic stem cell transplantation. The MDS-associated cytogenetic abnormalities that have been defined by karyotyping and FISH studies have already contributed substantially to our current understanding of the biology of malignant myeloid disorders, but the pathobiological meaning of common, recurrent chromosomal lesions such as del(5q), del(20q), and monosomy 7 is still unknown. The great diversity of the cytogenetic findings described in MDS highlights the molecular heterogeneity of this cluster of diseases. We review the common and pathophysiologically interesting genetic abnormalities associated with MDS, focusing on the clinical utility of conventional cytogenetic assays and selected FISH studies. In addition, we discuss a series of well-defined MDS-associated point mutations and outline the potential for further insights from newer techniques such as global gene expression profiling and array-based comparative genomic hybridization.

Molecular genetic diagnosis of pediatric cancer: current and emerging methods

A wide array of diagnostic tests are available to evaluate molecular abnormalities in pediatric cancer. Classic cytogenetics, FISH, flow cytometry, PCR, and Southern blot analysis are in widespread use throughout pediatric hospitals. Examples of the application of these methods in pediatric cancer diagnosis are reviewed. Newer methods such as CGH, SKY, gene expression microarrays and proteomic methods are under active investigation andwill almost certainly lead to significant advances in our ability to diagnose and treat pediatric cancer.

A single-center population-based consecutive series of 1500 cytogenetically investigated adult hematological malignancies: karyotypic features in relation to morphology, age and gender

During the 18-yr period 1976-93, a population-based series of 1586 adults with suspected or confirmed hematological malignancies were successfully cytogenetically investigated at a single center. Eighty-six cases were excluded due to unretrievable medical records or if analyzed only in remission or at relapse. The remaining 1500 medical records were reviewed regarding morphology and clinical parameters in order to investigate possible associations between karyotypic pattern (normal, 1, 2 or complex anomalies; specific abnormalities) and gender, age and morphological subgroups. The impact of time-period, i.e. 1976-87 vs. 1988-93, and referring center on cytogenetic findings was also studied. A total of 372 acute myeloid leukemias (AML), 389 myelodysplastic syndromes (MDS), 64 acute lymphoblastic leukemias (ALL) and 262 chronic myeloid leukemias (CML) were identified, altogether 1087 cases. Patients with other (n=261) or no hematological malignancies (n = 152) were excluded from the present analysis. Cytogenetic abnormalities were detected in 52% AML, 51 % MDS, 68% ALL and 97% CML, frequencies that did not differ significantly between the 2 time periods or referring centers. No significant age- or gender-related differences in karyotypic patterns were discerned in AML, MDS, ALL or CML, whereas the karyotypic patterns varied among the FAB groups in both AML (p= 0.001) and MDS (p < 0.001). The specific abnormalities t(8;21), t(15;17) and inv(16) were more common (p < 0.001) in younger AML patients and 5q- was more frequent in females with MDS (p<0.001). These findings indicate, in contrast to previous series, that neoplasia-associated karyotypic aberrations are not more common among older patients or in males.

Myelodysplastic syndrome presenting with clonal rearrangement isolated to chromosomal region 1q

Myelodysplastic syndrome (MDS) is a malignant hematologic disorder that may present with clinical features consistent with the diagnosis of severe aplastic anemia (SAA). Distinguishing the two disorders may depend on the presence of a clonal chromosomal abnormality. In the following, we report a case of MDS associated with what we believe to be a previously unreported clonal abnormality of chromosome 1q, a finding that enabled us to distinguish between MDS and SAA.

Chromosome aberrations in tenosynovial giant cell tumors and nontumorous synovial tissue

Five tenosynovial giant cell tumors--4 pigmented villonodular synovitis (PVNS) and 1 nodular tenosynovitis (NTS)--were investigated cytogenetically. Clonal chromosome aberrations were detected in 3 of them. One PVNS had t(7;16)(q22;q24) as the sole anomaly, whereas 1 PVNS and the NTS displayed aberrations suggesting clonal evolution: t(1;19)(p11;p12)/t(1;19), +12 and ins(5;1)(q31p34)/ins(5;1),t(2;4)(p23;q21), respectively. Including our 3 cases, a total of 6 tenosynovial giant cell tumors with karyotypic changes have been reported. Apart from 2 PVNS with trisomies 5 and 7, and 2 NTS with rearrangement of chromosome band 1p13, no recurrent chromosome change has been detected. Although the detection of clonal, acquired chromosome abnormalities has formerly generally been accepted as sufficient to conclude that a lesion is neoplastic, the interpretation of the pathogenetic significance of the karyotypic aberrations in synovial tumors is obscured by the fact that we have also detected comparable aberrations in obviously nonneoplastic synovial tissue. One of 2 lesions from patients with hemorrhagic synovitis carried a clonal del(13)(q12q21), and 2 of 4 synovectomy samples from patients with rheumatoid arthritis displayed -Y and -Y together with +7. The available cytogenetic data therefore cannot be used to resolve the controversy as to whether tenosynovial giant cell tumors are truly neoplastic or only reactive, inflammatory proliferations.

Karyotypic analysis in primary myelodysplastic syndromes

Cytogenetics has provided new insights into the biology and pathogenesis of myelodysplastic syndromes. In patients with refractory anemia, it has provided proof of clonality and has helped differentiate chronic myelomonocytic leukemia from chronic myeloid leukemia. As a prognostic tool, cytogenetics has been predictive of duration of survival and leukemic transformation. However, its role as an independent prognostic factor compared with recent prognostic scoring systems remains to be determined. New techniques such as fluorescent in situ hybridization using chromosome-specific DNA probes may expand the usefulness of cytogenetics. The prognostic impact of cytogenetics may not be fully realized until more effective treatments become available.

Analysis of karyotype, SCE, and point mutation of RAS oncogene in Indian MDS patients

Thirty Indian patients diagnosed as having primary myelodysplastic syndrome as per the French-American-British classification were investigated, on admission, for the frequencies of nonrandom karyotype abnormalities, sister chromatid exchange, and point mutations of the RAS oncogene. Successful karyotype analysis was possible in 24 patients, of whom 9 (37.5%) showed nonrandom karyotypic changes. Anomalies of chromosomes 5, 7, and 8 were detected in their bone marrow (BM). In addition, two new anomalies, del(8)(q22) and +19, were observed for the first time in our series. Six MDS patients were studied for SCE in either BM or peripheral blood. These data revealed a normal SCE incidence. Of the 10 MDS patients studied for point mutations of NRAS 12 and 61 and KRAS 12 and 61, one patient exhibited a base substitution at position 1 of the 12th codon of the KRAS gene. These data, gathered for the first time on the Indian patients, throw some light on the nature of genetic changes in MDS of our country.

Expression and function of beta-adrenergic receptors in human hematopoietic cell lines

We investigated the expression and functional characteristics of beta-adrenoceptors in a panel of 10 phenotypically different human hematopoietic cell lines. A binding assay with [125I]iodocyanopindolol as the ligand revealed that cell lines of myelomonocytic or histiocytic derivation (HL-60, ML-2, RC-2A, U-937) expressed high numbers of beta-adrenoceptors. An intermediate density of receptors was found in a non-T, non-B cell leukemia line (Nall-1), whereas T-cell (JM, CCRF-CEM), B-cell (Raji) or erythroleukemic cell lines (K-562, HEL) displayed minimal or undetectable binding of the radioligand. Isoprenaline-stimulated cAMP production by the cells correlated to their extent of beta-adrenoceptor expression. Southern blot hybridization analysis of genomic DNA from the cell lines with a 32P-labelled beta 2-adrenoceptor cDNA probe revealed no evidence for major rearrangement or amplification of the receptor gene. Incubation with isoprenaline in vitro suppressed the proliferation of the receptor-rich RC-2A cells but did not affect the growth rate of the receptor-deficient K-562 cells. Treatment with propranolol slightly enhanced the proliferation of the RC-2A cells but did not markedly alter the growth rate of two other cell lines, regardless of their beta-adrenoceptor status. These findings indicate a regulatory influence by the sympathoadrenergic system on selected cells of the myelomonocytic lineage.

Refractory anemia with excess of blasts in transformation. Clinical, hematologic, and cytogenetic findings in nine patients

Clinical, hematologic, and cytogenetic data of nine patients with refractory anemia with excess of blasts in transformation (RAEB-t), classified according to the French-American-British Cooperative Group for myelodysplastic syndrome (MDS), are reported. At diagnosis, eight out of nine cases, had chromosomal abnormalities and three out of nine developed acute leukemia. Karyotype studies allowed individualization of two groups of patients: five with nonrandom major karyotype abnormalities (MAKA) including hypodiploidy, chromosomes 5 and 7 involvement, at least four other abnormalities, and a poor prognosis (survival always under 3.5 months); and four patients with either normal karyotypes or minor karyotype abnormalities (MIKA) (no more than three abnormalities) and a better prognosis (survival from 14 to 38 months). Karyotype appears to be a major prognostic factor among RAEB-t.

Evolution of multiple cytogenetic clones and leukemic transformation in a case of myelodysplastic syndrome

The cytogenetic follow-up of a case of refractory anemia with excess of blasts (RAEB) that rapidly evolved to acute myeloblastic leukemia (M1-FAB type) is described. Bone marrow analysis at presentation revealed two chromosomally abnormal clones that shared an interstitial deletion of the long arm of chromosome 5 (5q-) and a terminal deletion of the short arm of chromosome 12 (12p-), but that differed from one another in the localization of a very similar segment of chromosome 17 (i.e. 17q11-12qter) on two clearly distinct karyotypic sites: 2q37 and 17q25. Fourteen percent of the metaphases examined bore the 2q+ marker and 38% the 17q+ marker; the remaining cells had a normal karyotype. A second study carried out 4 months later, at onset of the acute phase, revealed that the clone with normal karyotype had almost completely disappeared and that there had been an inversion in the ratio of the two abnormal cell populations. In the final study, made 1 month before death, the cells with t(2;17) had totally effaced the other clone. These findings seem to indicate that, among the karyotypic changes that occurred in an original clone with 5q- and 12p-, only the t(2;17) could have played a crucial role in the final leukemic transformation.

Relation between occupational exposure to organic solvents and chromosome aberrations in non-Hodgkin's lymphoma

Chromosome analysis of lymphoma cells was performed in 54 untreated patients with non-Hodgkin's lymphoma (NHL). 10 patients had a history of daily occupational handling of organic solvents for at least 1 year (exposed group) and 44 patients had never (or only for shorter periods) worked with solvents (unexposed group). There were no differences between exposed and unexposed patients regarding age, clinical stage or histologic malignancy grade. The patients were assigned to three categories: Patients with 0-4, 5-9, or greater than or equal to 10 cytogenetic events producing clonal aberrations of the lymphoma cells. The proportions of exposed patients in these categories were 2/26 (8%), 5/20 (25%) and 3/8 (38%); respectively, i.e. with increasing numbers of events there was an increasing probability of previous exposure to solvents (p = 0.035, trend analysis). 5 of 7 exposed patients (71%) with intermediate or high-grade lymphomas displayed translocations involving the band 14q32. Such 14q+ markers were found in only 5 out of 28 unexposed patients (18%) with lymphomas of comparable malignancy grade (p = 0.01). Among unexposed patients with intermediate or high-grade lymphoma the most common clonal aberration was 6q- which occurred in 10 out of 28 patients (36%). This abnormality was not observed in the exposed patients with lymphomas of corresponding malignancy grades (p = 0.08). It thus appears that the number of clonal chromosome aberrations is especially large in NHL patients with a history of occupational exposure to organic solvents. Moreover, such exposure may be associated with characteristic cytogenetic changes in the lymphoma cells.

Characteristic patterns of chromosome abnormalities in acute myeloid leukemia with Auer rods

Two hundred and four cytogenetically investigated patients with acute myeloid leukemia (AML) were evaluated for the presence (AR+) or absence (AR-) of Auer rods. Chromosome analysis was successful in 187 patients (92%). Seventy-eight patients (38%) were AR+. Cytogenetic abnormalities were detected in 35 (49%) AR+ patients and in 66 (57%) AR- patients. The proportion of patients with complex karyotypic changes (more than two aberrations) was significantly higher in the AR- group (p less than 0.01). Also, unidentifiable marker chromosomes were significantly more frequent in the AR- group (p less than 0.01). Twenty-one of 23 AR+, but none of 46 AR- patients with structural changes, had involvement of 21q22, 17q11-12, or 11p13-15. In contrast, structural changes of 1p, 5q, 7q, 9q, 11q, or 22q were present in 31 AR- but in only two AR+ patients. Four patients had translocations involving 21q22 without rearrangements of 8q22. All were AR+, but only one displayed M2 morphology. We draw the conclusion that chromosomal changes affecting 21q22 might be primarily related to AR formation, whereas, changes of 8q22 produce the characteristic differentiation pattern leading to M2 morphology, consistently found in AML with t(8;21)(q22;q22). With regard to numerical abnormalities, -7 and +8 occurred about equally often in the two groups, whereas, +11 and -Y, especially when present as the sole aberrations, were predominantly found in AR+ patients. In contrast, -5 and +21 were exclusively found in AR- patients. The results indicate that AR+ AML is characterized by a relatively limited number of chromosomal abnormalities that are different from the aberrations found in AR- patients. This feature has not been emphasized in previous studies correlating hematologic and cytogenetic findings in AML.