Chromosome-wide aneuploidy study (CWAS) in workers exposed to an established leukemogen, benzene

Evidence suggests that de novo, therapy-related and benzene-induced acute myeloid leukemias (AML) occur via similar cytogenetic and genetic pathways, several of which involve aneuploidy, the loss or gain of chromosomes. Aneuploidy of specific chromosomes has been detected in benzene-related leukemia patients as well as in healthy benzene-exposed workers, suggesting that aneuploidy precedes and may be a potential mechanism underlying benzene-induced leukemia. Here, we analyzed the peripheral blood lymphocytes of 47 exposed workers and 27 unexposed controls using a novel OctoChrome fluorescence in situ hybridization (FISH) technique that simultaneously detects aneuploidy in all 24 chromosomes. Through this chromosome-wide aneuploidy study (CWAS) approach, we found heterogeneity in the monosomy and trisomy rates of the 22 autosomes when plotted against continuous benzene exposure. In addition, statistically significant, chromosome-specific increases in the rates of monosomy [5, 6, 7, 10, 16 and 19] and trisomy [5, 6, 7, 8, 10, 14, 16, 21 and 22] were found to be dose dependently associated with benzene exposure. Furthermore, significantly higher rates of monosomy and trisomy were observed in a priori defined 'susceptible' chromosome sets compared with all other chromosomes. Together, these findings confirm that benzene exposure is associated with specific chromosomal aneuploidies in hematopoietic cells, which suggests that such aneuploidies may play roles in benzene-induced leukemogenesis.     

Hemoglobin and albumin adducts of benzene oxide among workers exposed to high levels of benzene

Benzene oxide (BO) reacts with cysteinyl residues in hemoglobin (Hb) and albumin (Alb) to form protein adducts (BO-Hb and BO-Alb), which are presumed to be specific biomarkers of exposure to benzene. We analyzed BO-Hb in 43 exposed workers and 42 unexposed controls, and BO-Alb in a subsample consisting of 19 workers and 19 controls from Shanghai, China, as part of a larger cross-sectional study of benzene biomarkers. The adducts were analyzed by gas chromatography-mass spectrometry following reaction of the protein with trifluoroacetic anhydride and methanesulfonic acid. When subjects were divided into controls (n = 42) and workers exposed to < or =31 (n = 21) and >31 p.p.m. (n = 22) benzene, median BO-Hb levels were 32.0, 46.7 and 129 pmol/g globin, respectively (correlation with exposure: Spearman r = 0.67, P < 0.0001). To our knowledge, these results represent the first observation in humans that BO-Hb levels are significantly correlated with benzene exposure. Median BO-Alb levels in these 3 groups were 103 (n = 19), 351 (n = 7) and 2010 (n = 12) pmol/g Alb, respectively, also reflecting a significant correlation with exposure (Spearman r = 0.90, P < 0.0001). The blood dose of BO predicted from both Hb and Alb adducts was very similar. These results clearly affirm the use of both Hb and Alb adducts of BO as biomarkers of exposure to high levels of benzene. As part of our investigation of the background levels of BO-Hb and BO-Alb found in unexposed persons, we analyzed recombinant human Hb and Alb for BO adducts. Significant levels of both BO-Hb (19.7 pmol/g) and BO-Alb (41.9 pmol/g) were detected, suggesting that portions of the observed background adducts reflect an artifact of the assay, while other portions are indicative of either unknown exposures or endogenous production of adducts.      

Prognostic Implications of Monosomies in Patients With Multiple Myeloma

BackgroundCytogenetic analysis aides in risk stratification for patients with multiple myeloma (MM). Although several cytogenetic aberrations have been reported to be prognostic, less is known about the association between the presence of monosomies and prognosis. The present study evaluated the prevalence and prognostic implications of monosomies in patients with MM.Materials and MethodsKaryotypes were determined using conventional cytogenetics and fluorescence in situ hybridization (FISH). The prognostic effect of monosomies was evaluated by comparison with the clinical factors in MM patients with normal karyotypes.ResultsKaryotypes were successfully determined in 167 of the 170 patients with MM. Of these 167 patients, 52 (31.1%) had abnormal karyotypes. Univariable analyses showed that a normal karyotype, hypodiploidy, monosomies of chromosomes 13 and 16, deletion or monosomy of 13q14, and loss of X detected by metaphase analysis were each associated with reduced progression-free survival (P < .05 for each). Univariable analyses showed that a normal karyotype, hypodiploidy, monosomies of chromosomes 13 and 16, deletion or monosomy of 13q14 detected by metaphase analysis and FISH-determined RB1 (13q)/TP53 (17p) deletion were each associated with reduced overall survival (P < .05 for each). Multivariable analysis showed that hypodiploidy detected by metaphase analysis was independently prognostic of shorter progression-free survival (P < .05 for each) and that hypodiploidy, monosomy 16, and loss of Y chromosome and FISH-determined TP53 (17p) deletion were associated with reduced overall survival (P < .05 for each).ConclusionIn addition to known cytogenetic abnormalities, such as monosomy 13, hypodiploidy, and TP53 (17p) deletion, monosomy 16 and loss of the Y chromosome have adverse prognostic implications in patients with MM.     

Hydroquinone, a benzene metabolite, increases the level of aneusomy of chromosomes 7 and 8 in human CD34-positive blood progenitor cells

Benzene is an established human carcinogen, producing leukemia, hematotoxicity and perhaps lymphoma. Its carcinogenicity is most likely dependent upon its conversion to phenol and hydroquinone, the latter being oxidized to the highly toxic 1,4-benzoquinone in the bone marrow. Exposure of human lymphocytes and cell lines to hydroquinone has previously been shown to cause various forms of genetic damage, including aneusomy and the loss and gain of chromosomes. However, the target cells for leukemogenesis are the pluripotent stem cells or early progenitor cells which carry the CD34 antigen (CD34(+) cells). In this study, human cord blood, which is particularly rich in CD34(+) cells, was exposed to hydroquinone for 72 h in a medium that favored CD34(+) cell survival and growth. CD34(+) and CD34(-) cells were then isolated. Fluorescence in situ hybridization was employed to determine the level of aneusomy of chromosomes 7 and 8 in both cell types. CD34(+) cells were generally more susceptible to aneusomy induction by hydroquinone than CD34(-) cells. Increased trisomy and monosomy of chromosomes 7 and 8 were observed in CD34(+) cells (P(trend) < 0.001), whereas in CD34(-) cells only an increased level of monosomy 7 was detected (P(trend) = 0.002). Particularly striking effects of hydroquinone were observed in CD34(+) cells on monosomy 7 and trisomy 8, two common clonal aberrations found in myeloid leukemias, suggesting that these aneusomies produced by hydroquinone in CD34(+) cells play a role in benzene-induced leukemogenesis.     

应用FISH技术对我国早期从事医用X线工作者的细胞遗传学评价

目的:对受到长期、低剂量率照射的我国早期从事医用X线工作者辐射损伤的远期效应进行细胞遗传学观察和评价.方法:用4号和7号全染色体探针和荧光原位杂交技术,分析25名早期X线工作者和10名对照者外周血淋巴细胞染色体畸变,并用Giemsa染色验证.结果:直观地表现出正常靶染色体和多种畸变.X线工作者的易位占其染色体总畸变的84 %;其他各种畸变率分别为插入(Ins)1.9%、双着丝粒(Dic)4.5%、无着丝粒断片(Ace)9.7 %;X线工作者的染色体易位率和总畸变率均明显高于对照组(P＜0.005).结论:早期医用X线工作者外周血淋巴细胞的染色体畸变以易位为主.     

Fluorescence in situ hybridization (FISH) evaluation of chromosomes 6, 7, 9 and 10 throughout human melanocytic tumorigenesis

Loss of the 9p21 region, 6q and 10q and gain of chromosome 7 are the most frequent chromosomal abnormalities found in human melanomas, but very few cytogenetic data are available regarding dysplastic and common naevi. To study the occurrence of the most consistent chromosomal changes during melanocytic tumorigenesis, archival samples from 30 common naevi and 30 naevus-associated melanomas were analysed by interphase fluorescence in situ hybridization (FISH) using centromeric probes for chromosomes 9 and 7 and locus-specific probes for 9p21, 6q11.1, 6q24.1, 10p15.3 and 10q23.1 regions. In naevus-associated melanomas, separate evaluations were made for sectors corresponding to residual naevus, dysplastic naevus, radial growth phase melanoma and vertical growth phase melanoma. No chromosomal aberrations were found in common naevi, but monosomy 7 was observed in one case. In naevus-associated melanomas, loss of the entire chromosome 9 or of the 9p21 region was observed in 56% of common and 54% of dysplastic naevus sectors, in 64% of radial growth phase melanoma and in 82% of vertical growth phase melanoma. Loss of the long arm of chromosome 6, monosomy 10 and deletion 10q were exclusively confined to radial (18% for both chromosomes) and vertical (29 and 59%, respectively) growth phase melanomas. Polysomy of chromosome 7 was detected only in melanoma sectors (radial growth phase, 14%; vertical growth phase, 59%). The high incidence of 9p21 loss in melanoma-associated naevi, which is maintained in all evolutionary phases of melanocytic tumorigenesis, and the complete absence of chromosomal aberrations in common naevi, strongly suggest that 9p21 loss may be regarded as a cytogenetic marker of melanocytic naevi with a high potential for progression.     

Intratumoral genetic heterogeneity in pilocytic astrocytomas revealed by CGH-analysis of microdissected tumor cells and FISH on tumor tissue sections

Pilocytic astrocytomas are the most frequent gliomas of childhood. The majority of cases show cytogenetic normal karyotypes. Although in diffuse gliomas TP53 gene mutations or deletions occur with significant frequency, the role in pilocytic astrocytomas remains unclear. Histomorphologically different areas of 14 pilocytic astrocytomas were microdissected and analyzed for genetic aberrations and heterogeneity. CGH analysis revealed gains of chromosome arm 4q and 6q mainly in areas of classic biphasic pattern, whereas pleomorphic areas presented gains of chromosome 6 and 8q. Using two-color fluorescence in situ hybridization (FISH) the spatial distribution of aneuploidies for chromosomes 7, 8, 17 and the TP53 gene were assessed on parallel sections. FISH analysis revealed a significant percentage of cells with interspersed heterozygous deletions of TP53 in all tumors (14/14), ten cases showed also monosomy 17. Besides gains of chromosomes 7 and 8, losses of these chromosomes were detected in the majority of tumors. In conclusion, pilocytic astrocytomas show a genetic heterogeneity associated with variations of histologic structure as well as an intratumoral heterogeneity observed on single cell level by FISH.     

Recurrent isochromosome 21 and multiple abnormalities in a patient suspected of having acute myeloid leukemia with eosinophilic differentiation—a rare case from South India

Acute myeloid leukemia (AML) is a phenotypically heterogeneous disorder. The M4 subtype of AML is frequently associated with the cytogenetic marker inversion 16 and/or the presence of eosinophilia. Blast crisis is the aggressive phase of the triphasic chronic myeloid leukemia (CML), which is a disease with Philadelphia (Ph) chromosome as the major abnormality. In the present study, we report a 76-year-old patient suspected of having AML with eosinophilic differentiation (AML-M4), which in clinical tests resembles CML blast crisis with multiple chromosomal abnormalities. Isochromosome 21 [i(21)(q10)] was the most recurrent feature noted in metaphases with 46 chromosomes. Ring chromosome, tetraploid endoreduplication, recurrent aneuploid clones with loss of X chromosome, monosomy 17, monosomy 7, and structural variation translocation (9;14) were also observed in this patient. Fluorescent in situ hybridization (FISH) confirmed the absence of Ph chromosome. This report shows how cytogenetic analyses revealed atypical structural aberrations in the M4 subtype of AML.     

The Benzene Metabolites Hydroquinone and Catechol Act in Synergy to Induce Dose-Dependent Hypoploidy and -5q31 in a Human Cell Line

Chronic exposure to high concentrations of benzene is associated with an increased incidence of myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML). Studies of patients occupationally exposed to benzene show a pattern of cytogenetic aberrations involving loss of all or part of chromosomes 5 and/or 7 as well as trisomy 8 and we have previously reported that hydroquinone (HQ) induces deletions of 5, 7 and 8. Benzene metabolism is a requirement for bone marrow toxicity and the phenolic metabolites, HQ and catechol (CAT), have been implicated in benzene hematotoxicity. A research project was designed to determine whether CAT by itself and in conjunction with HQ could directly induce loss of chromosome 5 and/or 7 and gain of chromosome 8. Using fluorescence in situ hybridization with chromosome-specific 5, 7, and 8 probes we demonstrate that 5 to 150 uM CAT does not produce chromosomal aberrations, however CAT and 25 uM HQ can act in synergy to induce dose dependent loss of these chromosomes. In addition HQ/CAT selectively induces -5q which is not observed for HQ only. These results demonstrate for the first time that CAT/HQ act in synergy to induce specific chromosome loss found in secondary MDWAML.     

The benzene metabolites hydroquinone and catechol act in synergy to induce dose-dependent hypoploidy and -5q31 in a human cell line

Chronic exposure to high concentrations of benzene is associated with an increased incidence of myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML). Studies of patients occupationally exposed to benzene show a pattern of cytogenetic aberrations involving loss of all or part of chromosomes 5 and/or 7 as well as trisomy 8 and we have previously reported that hydroquinone (HQ) induces deletions of 5, 7 and 8. Benzene metabolism is a requirement for bone marrow toxicity and the phenolic metabolites, HQ and catechol (CAT), have been implicated in benzene hematotoxicity. A research project was designed to determine whether CAT by itself and in conjunction with HQ could directly induce loss of chromosome 5 and/or 7 and gain of chromosome 8. Using fluorescence in situ hybridization with chromosome-specific 5, 7, and 8 probes we demonstrate that 5 to 150 uM CAT does not produce chromosomal aberrations, however CAT and 25 uM HQ can act in synergy to induce dose dependent loss of these chromosomes. In addition HQ/CAT selectively induces -5q which is not observed for HQ only. These results demonstrate for the first time that CAT/HQ act in synergy to induce specific chromosome loss found in secondary MDS/AML.     

Protein adducts of 1,4-benzoquinone and benzene oxide among smokers and nonsmokers exposed to benzene in China.

Hemoglobin (Hb) and albumin (Alb) adducts of the benzene metabolites benzene oxide (BO) and 1,4-benzoquinone (1,4-BQ) were analyzed by gas chromatography-mass spectrometry in 43 exposed workers and 44 unexposed controls from Shanghai, China, as part of a larger cross-sectional study of benzene biomarkers. When subjects were divided into controls (n = 44) and workers exposed to 31 ppm (n = 22) of benzene, median 1,4-BQ-Alb adducts were 2110, 5850, and 13,800 pmol/g Alb, respectively (correlation with exposure: Spearman r = 0.762; P < 0.0001); median BO-Alb adducts were 106, 417, and 2400 pmol/g Alb, respectively (Spearman r = 0.877; P < 0.0001); and median BO-Hb adducts were 37.1, 50.5, and 136 pmol/g Hb, respectively (Spearman r = 0.757; P < 0.0001). To our knowledge, this is the first observation that adducts of 1,4-BQ are significantly correlated with benzene exposure. When compared on an individual basis, Alb adducts of 1,4-BQ and BO and Hb adducts of BO were highly correlated with each other and with urinary phenol and hydroquinone (P < 0.0001 for all of the comparisons). Although detectable in the assays, Hb adducts of 1,4-BQ and both Hb and Alb adducts of 1,2-BQ produced erratic results and are not reported. Interestingly, cigarette smoking increased Alb adducts of 1,4-BQ but not of BO, suggesting that benzene from cigarette smoke was not the primary contributor to the 1,4-BQ adducts.     

Chromosome abnormalities in adult T-cell leukemia/lymphoma: a karyotype review committee report.

Karyotypes of 107 cases with adult T-cell leukemia/lymphoma (58 male, 49 female; 81 acute or lymphoma type, 26 chronic or smoldering type) were reviewed by a panel of cytogeneticists and were correlated with the subtypes of the disease. Clonal chromosome abnormalities were found in 103 (96%) cases, of which four had hypotetraploidy. Of 184 numerical abnormalities in the remaining 99 cases with near- or pseudodiploidy, trisomies for chromosomes 3 (21% of cases), 7 (10%), and 21 (9%), monosomy for X chromosome (38%) in the female, and loss of a Y chromosome (17%) in the male were more frequent than expected (P less than 0.01). Of 373 structural abnormalities in all the 103 aneuploid cases, translocations involving 14q32 (28%) or 14q11 (14%) and deletion of 6q (23%) were most frequent, followed by deletion of 10p (9%), 3q (8%), 5q, 9q, and 13q (7% each), and 1p and 7p (6% each). The proportion of cases with aneuploid clones (with greater than or less than 46 chromosomes), the average numbers per case of both numerical and structural abnormalities, and marker chromosomes were larger in the aggressive acute or lymphoma type than in the nonaggressive chronic or smoldering type (P less than 0.01). The combination of rearrangement in 14q32 and monosomy X (seven cases) or deletion of 10p (six cases), and that of trisomy 3 and deletion in 6q21 (six cases), occurred only in the acute or lymphoma type and may be associated with the aggressiveness in adult T-cell leukemia/lymphoma.     

Frequent deletions at 11q23 and 13q14 in B cell prolymphocytic leukemia (B-PLL).

Deletions of the long arm of chromosomes 11 and 13 are the most frequent structural chromosome aberrations in various types of lymphoproliferative disorders. However, these regions have not been studied so far in B cell prolymphocytic leukemia (B-PLL). We have investigated the incidence of 13q deletions in 18 B-PLL cases by fluorescence in situ hybridization (FISH), using molecular probes for the RB1 and D13S25 loci. Chromosome 11q deletions were evaluated by FISH using the yeast artificial chromosome (YAC) clone 755b11 from the chromosome 11q22.3-q23.1 region, which has been previously shown to be deleted in 20% of cases of chronic lymphocytic leukemia. Chromosome 11q23 deletions were found in 7/18 (39%) cases of B-PLL. Monoallelic loss of RB1, D13S25 and BRCA2 was present in 10/18 (55%), 6/18 (33%) and 3/18 (16%) of the cases, respectively. All the cases with D13S25 and BRCA2 deletion showed RB1 loss. Deletions of 13q14 and 11q23 are frequent chromosome aberrations in B-PLL and, in contrast to CLL, there is a preferential loss of RB1 with respect to the D13S25 locus suggesting that allelic loss of the RB1 gene may play a role in the pathogenesis of B-PLL.     

Analysis of chromosomes 3, 7, X and the EGFR gene in uterine cervical cancer progression

The aim of this study was to investigate the possible role of genetic alterations in the genesis and progression of cervical carcinomas. We analysed the 3, 7, X aneusomy of chromosomes and the status of the epidermal growth factor receptor (EGFR) gene by fluorescence in situ hybridisation (FISH) analysis. Polysomy of chromosomes 3 and X defined the transition from high-grade squamous intraepithelium lesions (HSIL) to cervical carcinoma. Chromosome 7 monosomy and polysomy did not show any statistical significant differences between the groups examined. When we compared the chromosomal aneusomies in all of the specimens using the Kruskal-Wallis test, significant differences (P = 0.0001, P = 0.0001 for chromosomes 3 and X, respectively) were observed. Using a ratio of the EGFR gene signals and chromosome 7 centromeric signals, no samples showed gene amplification. Our results demonstrate the importance of chromosomal 3 and X aneusomies in the development and progression from HSIL to cervical carcinoma, highlighting their usefulness as genetic markers for identifying SILs at high-risk of progression.     

Induction of chromosome-specific aneuploidy and micronuclei in human lymphocytes by metabolites of 1,3-butadiene

1,3-Butadiene is a carcinogen in rodents, but its potential carcinogenicity to humans remains controversial. Numerous studies have shown that butadiene and its metabolites cause sister chromatid exchanges in vitro and in vivo. To test for other types of genotoxicity, the micronucleus assay and fluorescence in situ hybridization (FISH) have been used to detect chromosome damage in human lymphocytes caused by two reactive metabolites of butadiene, diepoxybutane (DEB) and monoepoxybutene (MEB). DEB (0.5-5.0 microM) significantly increased micronucleus formation 4- to 6-fold (P <0.01) and MEB (1-500 microM) by 2- to 4-fold (P <0.01) over control levels. The ability of DEB and MEB to induce aneuploidy of chromosomes 7, 8, 12, and X was examined using dual-color FISH in both interphase and metaphase cells. These chromosomes were chosen because of their involvement in leukemogenesis. Both DEB and MEB caused dose-dependent increases in hyperdiploidy of chromosomes 12 and X, but had no discernible effect on chromosomes 7 and 8. These results suggest that DEB and MEB cause chromosome-specific aneuploidy in human cells. If formed in sufficient amounts, DEB and MEB may produce chromosome damage of the type found in leukemia following exposure to butadiene.      

Conventional cytogenetics and fluorescence in situ hybridization in persistent cytopenias and myelodysplastic syndromes in childhood

Accurate detection of the abnormal clone in children with persistent cytopenia (PC) may confirm the diagnosis of myelodysplastic syndrome (MDS) and determine prognosis and evolution of the disease. Bone marrow (BM) samples were obtained from 65 children, 11 of which were finally diagnosed as primary or secondary MDS. Ten to 20 G-banded metaphases were analyzed and FISH was performed using a-satellite probes for chromosomes 7 and 8. Conventional cytogenetic analysis (CCA) was successful in 40/65 samples, revealing clonal aberrations in 3 patients with MDS. FISH was successful in all cases, detecting monosomy 7 and trisomy 8 abnormal clones in 5 patients. Abnormalities were identified in 3/6 children with primary MDS and 3/5 with secondary MDS. None of the patients with PC of etiology other than MDS had a clonal abnormality in the BM. The results confirm the high incidence of chromosome abnormalities in childhood MDS and the sensitivity of FISH in detecting minor abnormal clones.     

Mutagen exposures and chromosome 3 aberrations in acute myelocytic leukemia.

Thirteen patients with acute myelocytic leukemia (AML) and with clonal aberrations involving chromosome 3 were studied. Three patients had monosomy 3, four had trisomy 3, and six had structural aberrations of chromosome 3. In the majority of cases chromosome 3 aberrations were parts of complex karyotypes, but in two patients, the abnormalities appeared as single aberrations, one as an interstitial deletion del(3)(p13p21) and the other as monosomy 3. All breakpoints of chromosome 3 were found in the fragile site regions 3p14.2, 3q21 and 3q26-27. All patients with monosomy 3 or structural aberrations of chromosome 3 and one of the four patients with trisomy 3 had been exposed to mutagens, such as occupational exposures to organic solvents and/or petroleum products or treatments with irradiation or antineoplastic agents. The association among mutagen exposure, structural chromosome 3 aberrations and fragile sites in AML may indicate that targeting of the mutagens to these sites is of importance for the etiology of the disease. Leukemia (2000) 14, 112-118.     

Extramedullary relapse despite graft-versus-leukemia effect after bone marrow transplantation in a girl with juvenile myelomonocytic leukemia.

A 12 year-old girl with juvenile myelomonocytic leukemia (JMML) and monosomy 7 underwent allogeneic bone marrow transplantation (BMT) from her HLA-matched brother. To monitor the engraftment and the course of the disease we used fluorescence in situ hybridization (FISH) with probes specific for the centromeres of chromosomes X, Y and 7. Complete hematological remission was achieved and confirmed by the virtually exclusive presence of normal male cells in the bone marrow (BM). Acute graft-versus host disease (GvHD) was treated with prednisone and cyclosporine A (CSA) and female cells with monosomy 7 reoccurred in the peripheral blood (PB) and BM. After discontinuation of the immunosuppressive therapy, the leukemic cells with monosomy 7 disappeared again from these compartments. One year after transplantation, isolated extramedullary relapses occurred in lymph nodes and skin, followed by dissemination of blast cells into the BM, whereas the PB cells remained of donor origin. The fact that the leukemic cells fluctuated with the intensity of the immunosuppressive treatment provides evidence of a graft versus leukemia (GvL) effect in this unusually old girl with JMML with a unique extramedullary disease progression.     

Interphase cytogenetics of hematological cancer: comparison of classical karyotyping and in situ hybridization using a panel of eleven chromosome specific DNA probes

Numerical chromosome aberrations were detected in hematological cancers by nonradioactive in situ hybridization (ISH) procedures, using centromere specific probes for chromosomes 1, 7, 8, 9, 10, 11, 16, 17, 18, X, and Y. All 15 cases could be evaluated by ISH for these 11 probes. Our experiments show that in seven of these randomly selected leukemia bone marrow cell suspensions numerical aberrations for one or two chromosomes could be detected by this method. The results of ISH on interphase nuclei and in some cases on metaphase preparations were compared with karyotyping data. Seven cases of chromosomal aberrations observed with ISH (three for monosomy and four for trisomy) were confirmed by this classical cytogenetic technique, whereas in five instances an aberration was found only with ISH (twice for monosomy, twice for trisomy, and one disomy for the Y-probe). One case of a trisomy for chromosome 1 observed by ISH on interphase nuclei could be explained by a marker chromosome, a finding that was further substantiated by ISH on metaphase spreads. In this case double-target ISH on interphase cells with the probes for chromosomes 1 and 16 strongly suggested a translocation between these chromosomes. Also, in one case a marker chromosome could be characterized as a translocation between chromosomes 7 and 17. In this latter case the cytogenetic examinations revealed only monosomy for chromosomes 7 and 17 in addition to noncharacterized marker chromosomes. Our results indicate that the nonradioactive ISH procedure in combination with chromosome specific repetitive centromeric probes is a powerful tool for studying both numerical and structural chromosomal aberrations in interphase nuclei of leukemias. It may therefore become a valuable and routine diagnostic tool in addition to the existing karyotyping procedures.     

Quantitation of minimal residual disease in acute myelogenous leukemia and myelodysplastic syndromes in complete remission by molecular cytogenetics of progenitor cells.

Detection of karyotypic clonal abnormalities are prognostically useful in patients with acute myelogenous leukemia (AML) and myelodysplastic syndromes (MDS), but cytogenetic methods are not sensitive enough to detect low numbers of residual leukemic cells in patients who have achieved complete remission (CR). Fluorescence in situ hybridization (FISH) and fluorescence activated cell sorting (FACS) were used to investigate the frequency and presence of minimal residual disease (MRD) in AML and MDS patients (n = 28) with monosomy of chromosomes 7, 17 and 18 and trisomy of chromosomes 6, 8, 9 and 10 in CR. MRD was detected in all patients with monosomy 7 (n = 10) and followed by relapse in eight patients after 4.8 +/- 3.1 months. In contrast, persistent leukemic cells occurred in 11/12 patients with trisomy 8, but only three of them relapsed after 7.7 +/- 4.0 months. Cox regression analysis showed that cytogenetic class and levels of clonal cells at CR were related to time to relapse (P = 0.001). The level of MRD identified patients at high and low risk of relapse. High absolute levels of proliferating residual leukemic cells correlated with monosomy 7 and high risk of relapse.