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Radiat Res, 174(1), 20–26
July, 2010

Influence of nuclear geometry on the formation of genetic rearrangementsin human cells.

M. Durante, D. Pignalosa, J. A. Jansen, X. F. Walboomers, S. Ritter

Interphase chromosomes are divided into discrete domains, with limited overlapping and movement. We explored the role of nuclear topology in the formation of chromosome aberrations by irradiating normal human fibroblasts with high-energy heavy ions from different directions. Cells with elliptical nuclei were grown in an aligned manner onto micrometer grooved culturing substrates to have a predetermined orientation with respect to the accelerated iron ions. Particles were directed either perpendicular to the cell layer or along the major or minor axis of the nucleus. Analysis of chromosome aberrations by mFISH showed that, at the same radiation dose, the yield of chromosomal damage and its complexity are largely modified by the irradiation geometry. The results demonstrate that the architecture of the cell nucleus determines the formation of chromosomal rearrangements.

Cancer Genet Cytogenet, 200(2), 79–99
July, 2010

Transgenic oncogenes induce oncogene-independent cancers with individualkaryotypes and phenotypes.

Andreas Klein, Nan Li, Joshua M Nicholson, Amanda A McCormack, Adolf Graessmann, Peter Duesberg

Cancers are clones of autonomous cells defined by individual karyotypes, much like species. Despite such karyotypic evidence for causality, three to six synergistic mutations, termed oncogenes, are generally thought to cause cancer. To test single oncogenes, they are artificially activated with heterologous promoters and spliced into the germ line of mice to initiate cancers with collaborating spontaneous oncogenes. Because such cancers are studied as models for the treatment of natural cancers with related oncogenes, the following must be answered: 1) which oncogenes collaborate with the transgenes in cancers; 2) how do single transgenic oncogenes induce diverse cancers and hyperplasias; 3) what maintains cancers that lose initiating transgenes; 4) why are cancers aneuploid, over- and underexpressing thousands of normal genes? Here we try to answer these questions with the theory that carcinogenesis is a form of speciation. We postulate that transgenic oncogenes initiate carcinogenesis by inducing aneuploidy. Aneuploidy destabilizes the karyotype by unbalancing teams of mitosis genes. This instability thus catalyzes the evolution of new cancer species with individual karyotypes. Depending on their degree of aneuploidy, these cancers then evolve new subspecies. To test this theory, we have analyzed the karyotypes and phenotypes of mammary carcinomas of mice with transgenic SV40 tumor virus- and hepatitis B virus-derived oncogenes. We found that (1) a given transgene induced diverse carcinomas with individual karyotypes and phenotypes; (2) these karyotypes coevolved with newly acquired phenotypes such as drug resistance; (3) 8 of 12 carcinomas were transgene negative. Having found one-to-one correlations between individual karyotypes and phenotypes and consistent coevolutions of karyotypes and phenotypes, we conclude that carcinogenesis is a form of speciation and that individual karyotypes maintain cancers as they maintain species. Because activated oncogenes destabilize karyotypes and are dispensable in cancers, we conclude that they function indirectly, like carcinogens. Such oncogenes would thus not be valid models for the treatment of cancers.

Mol Biol Cell, 21(4), 511–520
February, 2010

Alzheimer Abeta peptide induces chromosome mis-segregation and aneuploidy,including trisomy 21: requirement for tau and APP.

Antoneta Granic, Jaya Padmanabhan, Michelle Norden, Huntington Potter

Both sporadic and familial Alzheimer's disease (AD) patients exhibit increased chromosome aneuploidy, particularly trisomy 21, in neurons and other cells. Significantly, trisomy 21/Down syndrome patients develop early onset AD pathology. We investigated the mechanism underlying mosaic chromosome aneuploidy in AD and report that FAD mutations in the Alzheimer Amyloid Precursor Protein gene, APP, induce chromosome mis-segregation and aneuploidy in transgenic mice and in transfected cells. Furthermore, adding synthetic Abeta peptide, the pathogenic product of APP, to cultured cells causes rapid and robust chromosome mis-segregation leading to aneuploid, including trisomy 21, daughters, which is prevented by LiCl addition or Ca(2+) chelation and is replicated in tau KO cells, implicating GSK-3beta, calpain, and Tau-dependent microtubule transport in the aneugenic activity of Abeta. Furthermore, APP KO cells are resistant to the aneugenic activity of Abeta, as they have been shown previously to be resistant to Abeta-induced tau phosphorylation and cell toxicity. These results indicate that Abeta-induced microtubule dysfunction leads to aneuploid neurons and may thereby contribute to the pathogenesis of AD.

Pediatr Blood Cancer, 54(1), 158–160
January, 2010

Detection of early precursors of t(12;21) positive pediatric acutelymphoblastic leukemia during follow-up.

Renáta László, Donát Alpár, Béla Kajtár, Agnes Lacza, Gábor Ottóffy, Csongor Kiss, Katalin Bartyik, Kálmán Nagy, László Pajor

DNA-, RNA-, and cell-based methods provide different biologic information for determining the presence of minimal residual disease (MRD). We monitored the responses of patients with pediatric acute lymphoblastic leukemia (pALL) using DNA markers, TEL/AML1 expression, and scanning fluorescence microscopy (SFM). Using SFM, 36\% of patients exhibited 1.5-3.1 log and 2.9-4.2 log higher MRD levels compared with those based on DNA and RNA markers, respectively. CD10+ ancestor cells with germline antigen receptors, but silent TEL/AML1 expression, may reside in the lymphoid stem cell compartment of treated t(12;21)-positive patients and might act as a potential source of cells for late relapses.

Anal Cell Pathol (Amst), 33(2), 105–112

Automated analysis of protein expression and gene amplification withinthe same cells of paraffin-embedded tumour tissue.

Timo Gaiser, Lissa Berroa-Garcia, Ralf Kemmerling, Aparajita Dutta, Thomas Ried, Kerstin Heselmeyer-Haddad

The simultaneous detection of protein expression and gene copy number changes in patient samples, like paraffin-embedded tissue sections, is challenging since the procedures of immunohistochemistry (IHC) and Fluorescence in situ Hybridization (FISH) negatively influence each other which often results in suboptimal staining.Therefore, we developed a novel automated algorithm based on relocation which allows subsequent detection of protein content and gene copy number changes within the same cell.Paraffin-embedded tissue sections of colorectal cancers were stained for CD133 expression. IHC images were acquired and image coordinates recorded. Slides were subsequently hybridized with fluorescently labeled DNA probes. FISH images were taken at the previously recorded positions allowing for direct comparison of protein expression and gene copy number signals within the same cells/tissue areas. Relocation, acquisition of the IHC and FISH images, and enumeration of FISH signals in the immunophenotyped tumour areas were done in an automated fashion.Automated FISH analysis was performed on 13 different colon cancer samples that had been stained for CD133; each sample was scored for MYC, ZNF217 and Chromosome 6 in CD133 positive and negative glands. From the 13 cases four (31\%) showed amplification for the MYC oncogene and seven of 13 (54\%) cases were amplified for ZNF217. There was no significant difference between CD133 positive tumour and CD133 negative tumour cells.The technique and algorithm presented here enables an easy and reproducible combination of IHC and FISH based on a novel automated algorithm using relocation and automated spot counting.

Cancer Manag Res, 2, 213–218

Positive response to neoadjuvant cyclophosphamide and doxorubicinin topoisomerase II nonamplified/HER2/neu negative/polysomy 17 absentbreast cancer patients.

Henry G Kaplan, Judith A Malmgren, Mary Atwood, Lynn C Goldstein

Human epidermal growth factor receptor 2 (HER2)/neu, topoisomerase II alpha (TOP2A), and polysomy 17 may predict tumor responsiveness to doxorubicin (DOX) therapy.We identified neoadjuvant DOX/cyclophosphamide treated breast cancer patients in our registry from 1997 to 2008 with sufficient tissue for testing (n = 34). Fluorescence in situ hybridization (FISH) testing was done on deparaffinized tissue sections pretreated using vendor's standard protocol modification, and incubated with US Food and Drug Administration approved Abbott Diagnostics Vysis PathVysion™ probe set, including Spectrum-Green-conjugated probe to ?-satellite DNA located at the centromere of chromosome 17 (17p11.1-q11.1) and a Spectrum-Orange-conjugated probe to the TOP2A gene. Morphometric analysis was performed using a MetaSystems image analysis system. Manual counting was performed on all samples in which autofluorescence and/or artifact prevented the counting of sufficient numbers of cells. A ratio >2.0 was considered positive for TOP2A amplification. Polysomy 17 (PS17) presence was defined as signals of ?2.5. Outcomes were pathological complete response (pCR), partial response (PR), and nonresponse (NR).Of 34 patients tested, one was TOP2A amplified (hormone receptor negative/HER2 negative, partial responder). The subset of TOP2A nonamplified, HER2 negative, and PS17 absent (n = 23) patients had treatment response: pCR = 2 (9\%), PR = 14 (61\%), and NR = 7 (30\%). Including the two PS17 present and HER2-positive patients (n = 33), 76\% of TOP2A nonamplified patients had pCR or PR.We observed substantial treatment response in patients lacking three postulated predictors that would be difficult to attribute to cyclophosphamide alone. Patients who are HER2 negative and lack TOP2A amplification and PS17 should not be excluded from receiving DOX-containing regimens.

Science, 326(5957), 1230
November, 2009

Induced chromosomal proximity and gene fusions in prostate cancer.

Ram-Shankar Mani, Scott A Tomlins, Kaitlin Callahan, Aparna Ghosh, Mukesh K Nyati, Sooryanarayana Varambally, Nallasivam Palanisamy, Arul M Chinnaiyan

Gene fusions play a critical role in cancer progression. The mechanisms underlying their genesis and cell type specificity are not well understood. About 50\% of human prostate cancers display a gene fusion involving the 5' untranslated region of TMPRSS2, an androgen-regulated gene, and the protein-coding sequences of ERG, which encodes an erythroblast transformation-specific (ETS) transcription factor. By studying human prostate cancer cells with fluorescence in situ hybridization, we show that androgen signaling induces proximity of the TMPRSS2 and ERG genomic loci, both located on chromosome 21q22.2. Subsequent exposure of the cells to gamma irradiation, which causes DNA double-strand breaks, facilitates the formation of the TMPRSS2-ERG gene fusion. These results may help explain why TMPRSS2-ERG fusions are restricted to the prostate, which is dependent on androgen signaling.

Science Express, 29. Oct. 2009
October, 2009

Induced chromosomal proximity and gene fusions in prostate cancer.

Mani, R.S., Tomlins, S.A., Callahan, K., Ghosh, A., Nyati, M.K., Varambally, S., Palanisamy, N., Chinnaiyan, A.M.

Gene fusions play a critical role in cancer progression. The mechanisms underlying their genesis and cell type specificity are not well understood. About 50% of human prostate cancers display a gene fusion involving the 5’untranslated region of TMPRSS2, an androgen-regulated gene, and the protein-coding sequences of ERG, which encodes an ETS transcription factor. Studying human prostate cancer cells by fluorescence in situ hybridization, we show that androgen signaling induces proximity of the TMPRSS2 and ERG genomic loci, both located on chromosome 21q22.2. Subsequent exposure of the cells to gamma-irradiation, which causes DNA double strand breaks, facilitates the formation of the TMPRSS2-ERG gene fusion. These results may help explain why TMPRSS2-ERG fusions are restricted to the prostate, which is dependent on androgen signaling.

Cancer Genet Cytogenet, 193(2), 123–126
September, 2009

A case of childhood acute myeloid leukemia AML (M5) with a neocentricchromosome neo(1)(qter–>q23 approximately 24::q23 approximately24–>q43–>neo–>q43–>qter) and tetrasomy of chromosomes 8 and 21.

de Figueiredo, Amanda Faria, Hasmik Mkrtchyan, Thomas Liehr, Eliane Maria Soares Ventura, de Jesus Marques-Salles, Terezinha, Neide Santos, Raul Corrêa Ribeiro, Eliana Abdelhay, Maria Luiza Macedo Silva

Hyperdiploidy is rarely observed in childhood acute myeloid leukemia (AML). Described here is the case of a 2(1/2)-year-old girl with AML-M5 and 51 chromosomes characterized by double tetrasomy of chromosomes 8 and 21 and also a neocentric derivative chromosome neo(1)(qter–>q23 approximately 24::q23 approximately 24–>q43–>neo–>q43–>qter). Little is known about the prognostic significance of these chromosomal abnormalities in childhood AML. In the actual case, complete remission was achieved after chemotherapy, which continued for 7 months. No acquired neocentric chromosome 1 has been described previously, even though neocentromere formation has been reported for other chromosomes in neoplasms.

J Natl Cancer Inst, 101(10), 736–750
May, 2009

Ki67 index, HER2 status, and prognosis of patients with luminal Bbreast cancer.

Maggie C U. Cheang, Stephen K. Chia, David Voduc, Dongxia Gao, Samuel Leung, Jacqueline Snider, Mark Watson, Sherri Davies, Philip S. Bernard, Joel S. Parker, Charles M. Perou, Matthew J. Ellis, Torsten O. Nielsen

Gene expression profiling of breast cancer has identified two biologically distinct estrogen receptor (ER)-positive subtypes of breast cancer: luminal A and luminal B. Luminal B tumors have higher proliferation and poorer prognosis than luminal A tumors. In this study, we developed a clinically practical immunohistochemistry assay to distinguish luminal B from luminal A tumors and investigated its ability to separate tumors according to breast cancer recurrence-free and disease-specific survival.Tumors from a cohort of 357 patients with invasive breast carcinomas were subtyped by gene expression profile. Hormone receptor status, HER2 status, and the Ki67 index (percentage of Ki67-positive cancer nuclei) were determined immunohistochemically. Receiver operating characteristic curves were used to determine the Ki67 cut point to distinguish luminal B from luminal A tumors. The prognostic value of the immunohistochemical assignment for breast cancer recurrence-free and disease-specific survival was investigated with an independent tissue microarray series of 4046 breast cancers by use of Kaplan-Meier curves and multivariable Cox regression.Gene expression profiling classified 101 (28\%) of the 357 tumors as luminal A and 69 (19\%) as luminal B. The best Ki67 index cut point to distinguish luminal B from luminal A tumors was 13.25\%. In an independent cohort of 4046 patients with breast cancer, 2847 had hormone receptor-positive tumors. When HER2 immunohistochemistry and the Ki67 index were used to subtype these 2847 tumors, we classified 1530 (59\%, 95\% confidence interval [CI] = 57\% to 61\%) as luminal A, 846 (33\%, 95\% CI = 31\% to 34\%) as luminal B, and 222 (9\%, 95\% CI = 7\% to 10\%) as luminal-HER2 positive. Luminal B and luminal-HER2-positive breast cancers were statistically significantly associated with poor breast cancer recurrence-free and disease-specific survival in all adjuvant systemic treatment categories. Of particular relevance are women who received tamoxifen as their sole adjuvant systemic therapy, among whom the 10-year breast cancer-specific survival was 79\% (95\% CI = 76\% to 83\%) for luminal A, 64\% (95\% CI = 59\% to 70\%) for luminal B, and 57\% (95\% CI = 47\% to 69\%) for luminal-HER2 subtypes.Expression of ER, progesterone receptor, and HER2 proteins and the Ki67 index appear to distinguish luminal A from luminal B breast cancer subtypes.

Hum Mol Genet, 18(6), 1017–1027
March, 2009

Telomere elongation involves intra-molecular DNA replication in cellsutilizing alternative lengthening of telomeres.

Alessandra Muntoni, Axel A. Neumann, Mark Hills, Roger R. Reddel

Alternative lengthening of telomeres (ALT) is a telomere length maintenance mechanism based on recombination, where telomeres use other telomeric DNA as a template for DNA synthesis. About 10\% of all human tumors depend on ALT for their continued growth, and understanding its molecular details is critically important for the development of cancer treatments that target this mechanism. We have previously shown that telomeres of ALT-positive human cells can become lengthened via inter-telomeric copying, i.e. by copying the telomere of another chromosome. The possibility that such telomeres could elongate by using other sources of telomeric DNA as copy templates has not been investigated previously. In this study, we have determined whether a telomere can become lengthened by copying its own sequences, without the need for using another telomere as a copy template. To test this, we transduced an ALT cell line with a telomere-targeting construct and obtained clones with a single tagged telomere. We showed that the telomere tag can be amplified without the involvement of other telomeres, indicating that telomere elongation can also occur by intra-telomeric DNA copying. This is the first direct evidence that the ALT mechanism involves more than one method of telomere elongation.

Cancer Genet Cytogenet, 189(1), 59–62
February, 2009

A new chromosomal three-way rearrangement involving MLL masked bya t(9;19)(p11;p13) in an infant with acute myeloid leukemia.

de Jesus Marques-Salles, Terezinha, Thomas Liehr, Hasmik Mkrtchyan, Susana C Raimondi, de Souza, Mariana Tavares, de Figueiredo, Amanda Faria, Soraia Rouxinol, Fernanda C Jordy Macedo, Eliana Abdelhay, Neide Santos, Maria Luiza Macedo Silva

Infants diagnosed with acute myelogenous leukemia (AML) are likely to have subtypes M4 or M5 characterized by 11q23 abnormalities like a t(9;11)(p22;q23). Detection of all possible types of chromosomal abnormalities, including mixed lineage leukemia (MLL) gene rearrangements at 11q23, is of importance for the identification of biological subgroups, which might differ in drug resistance and/or clinical outcome. Here, we report the clinical, conventional banding and molecular cytogenetics data of a 6-month-old boy with an AML-M5 presenting with a unique cryptic rearrangement involving the MLL gene: a three-way t(9;19;11)(p11.2;p13.1;q23).

Mol Cytogenet, 2, 7

Unbalanced chromosome 1 abnormalities leading to partial trisomy1q in four infants with Down syndrome and acute megakaryocytic leukemia.

Maria Luiza Macedo Silva, do Socorro Pombo-de-Oliveira, Maria, Susana C Raimondi, Hasmik Mkrtchyan, Eliana Abdelhay, de Figueiredo, Amanda Faria, de Souza, Mariana Tavares, Daniela Ribeiro Ney Garcia, de Ventura, Eliane Maria Soares, de Sousa, Adriana Martins, Thomas Liehr

ABSTRACT: BACKGROUND: Children with Down syndrome (DS) have an increased risk of childhood acute leukemia, especially acute megakaryoblastic leukemia (AMKL) also called acute myeloid leukemia (AML) type M7. Here four yet unreported infants with such malignancies are reported. RESULTS: An unbalanced translocation involving chromosome 1 was identified by GTG banding in all cases. These were characterized in more detail by molecular cytogenetic approaches. Additional molecular analysis revealed in three of the four cases mutations in exon 2 of the GATA binding protein 1 (globin transcription factor 1), located in Xp11.23. CONCLUSION: Our results corroborate that abnormalities of chromosome 1 are common in DS-associated AMKL. Whether this chromosomal region contains gene(s) involved in hematopoietic malignant transformation remains to be determined.

Cancer Genet Cytogenet, 188, 1- 25

Cancer-causing karyotypes: chromosomal equilibria between destabilizing aneuploidy and stabilizing selection for oncogenic function.

L. Li, A.A. McCormack, J.M. Nicholson, A. Fabarius, R. Hehlmann, R.K. Sachs, P.H. Duesberg

The chromosomes of cancer cells are unstable, because of aneuploidy. Despite chromosomal instability, however, cancer karyotypes are individual and quasi-stable, as is evident especially from clonal chromosome copy numbers and marker chromosomes. This paradox would be resolved if the karyotypes in cancers represent chromosomal equilibria between destabilizing aneuploidy and stabilizing selection for oncogenic function. To test this hypothesis, we analyzed the initial and long-term karyotypes of seven clones of newly transformed human epithelial, mammary, and muscle cells. Approximately 1 in 100,000 such cells generates transformed clones at 2-3 months after introduction of retrovirus-activated cellular genes or the tumor virus SV40. These frequencies are too low for direct transformation, so we postulated that virus-activated genes initiate transformation indirectly, via specific karyotypes. Using multicolor fluorescence in situ hybridization with chromosome-specific DNA probes, we found individual clonal karyotypes that were stable for at least 34 cell generations-within limits, as follows. Depending on the karyotype, average clonal chromosome numbers were stable within +/- 3%, and chromosome-specific copy numbers were stable in 70-100% cells. At any one time, however, relative to clonal means, per-cell chromosome numbers varied +/-18% and chromosome-specific copy numbers varied +/-1 in 0-30% of cells; unstable nonclonal markers were found within karyotype-specific quotas of <1% to 20% of the total chromosome number. For two clones, karyotypic ploidies also varied. With these rates of variation, the karyotypes of transformed clones would randomize in a few generations unless selection occurs. We conclude that individual aneuploid karyotypes initiate and maintain cancers, much like new species. These cancer-causing karyotypes are in flexible equilibrium between destabilizing aneuploidy and stabilizing selection for transforming function. Karyotypes as a whole, rather than specific mutations, explain the individuality, fluidity, and phenotypic complexity of cancers.

EMBO J, 28(7), 799-809

Control of telomere length by a trimming mechanism that involves generation of t-circles

HA Pickett, AJ Cesare, RL Johnston, AA Neumann, RR Reddel

Telomere lengths are maintained in many cancer cells by the ribonucleoprotein enzyme telomerase but can be further elongated by increasing telomerase activity through the overexpression of telomerase components. We report here that increased telomerase activity results in increased telomere length that eventually reaches a plateau, accompanied by the generation of telomere length heterogeneity and the accumulation of extrachromosomal telomeric repeat DNA, principally in the form of telomeric circles (t-circles). Telomeric DNA was observed in promyelocytic leukemia bodies, but no intertelomeric copying or telomere exchange events were identified, and there was no increase in telomere dysfunction-induced foci. These data indicate that human cells possess a mechanism to negatively regulate telomere length by trimming telomeric DNA from the chromosome ends, most likely by t-loop resolution to form t-circles. Additionally, these results indicate that some phenotypic characteristics attributed to alternative lengthening of telomeres (ALT) result from increased mean telomere length, rather than from the ALT mechanism itself.

Diagn Mol Pathol, 18, 119- 124

Nuclear FISH. Automation, analysis, and interpretation.

G.B. Côté

Automated fluorescent in situ hybridization scanners are more rapid and accurate than people and are becoming more popular. However, the methods used by these machines to score and interpret fluorescent in situ hybridization signals in nuclei are still those used by human observers. A new approach is presented to make the software classify the fluorescent patterns in additional relevant categories, thus avoiding the rejection of relevant information and consequent bias. The statistical interpretation of the fluorescent pattern distributions is carried out with a maximum likelihood estimation of the most likely proportions of various cell lines in the sample, and thus determines the diagnosis and the level of mosaicism in a single step. This approach is faster and more accurate than those used by human observers. It requires the scanning of fewer nuclei, less efforts for validation, and it makes the interpretation of results much simpler.

Mol Cytogenet, 2, 16

Molecular cytogenetic characterisation of a mosaic add(12)(p13.3)with an inv dup(3)(q26.31 –> qter) detected in an autistic boy.

Isabel M Carreira, Joana B Melo, Carlos Rodrigues, Liesbeth Backx, Joris Vermeesch, Anja Weise, Nadezda Kosyakova, Guiomar Oliveira, Eunice Matoso

ABSTRACT: BACKGROUND: Inverted duplications (inv dup) of a terminal chromosome region are a particular subset of rearrangements that often results in partial tetrasomy or partial trisomy when accompanied by a deleted chromosome. Associated mosaicism could be the consequence of a post-zygotic event or could result from the correction of a trisomic conception. Tetrasomies of distal segments of the chromosome 3q are rare genetic events and their phenotypic manifestations are diverse. To our knowledge, there are only 12 cases reported with partial 3q tetrasomy. Generally, individuals with this genomic imbalance present mild to severe developmental delay, facial dysmorphisms and skin pigmentary disorders. RESULTS: We present the results of the molecular cytogenetic characterization of an unbalanced mosaic karyotype consisting of mos 46,XY,add(12)(p13.3) [56]/46,XY [44] in a previously described 11 years old autistic boy, re-evaluated at adult age. The employment of fluorescence in situ hybridization (FISH) and multicolor banding (MCB) techniques identified the extra material on 12p to be derived from chromosome 3, defining the additional material on 12p as an inv dup(3)(qter –> q26.3::q26.3 –> qter). Subsequently, array-based comparative genomic hybridization (aCGH) confirmed the breakpoint at 3q26.31, defining the extra material with a length of 24.92 Mb to be between 174.37 and 199.29 Mb. CONCLUSION: This is the thirteenth reported case of inversion-duplication 3q, being the first one described as an inv dup translocated onto a non-homologous chromosome. The mosaic terminal inv dup(3q) observed could be the result of two proposed alternative mechanisms. The most striking feature of this case is the autistic behavior of the proband, a characteristic not shared by any other patient with tetrasomy for 3q26.31 –> 3qter. The present work further illustrates the advantages of the use of an integrative cytogenetic strategy, composed both by conventional and molecular techniques, on providing powerful information for an accurate diagnosis. This report also highlights a chromosome region potentially involved in autistic disorders.

PLoS One, 4, 0- 0

Human telomere length correlates to the size of the associated chromosome arm.

J.L. Wise, R.J. Crout, D.W. McNeil, R.J. Weyant, M.L.Marazita, S.L. Wenger

The majority of human telomere length studies have focused on the overall length of telomeres within a cell. In fact, very few studies have examined telomere length for individual chromosome arms. The objective of this study was to examine the relationship between chromosome arm size and the relative length of the associated telomere. Quantitative Fluorescence In Situ Hybridization (Q-FISH) was used to measure the relative telomere length of each chromosome arm in metaphases from cultured lymphocytes of 17 individuals. A statistically significant positive correlation (r = 0.6) was found between telomere length and the size of the associated chromosome arm, which was estimated based on megabase pair measurements from

Molecular Cytogenetics, 2, 0- 0

Automated detection of residual cells after sex-mismatched stem-cell transplantation - evidence for presence of disease-marker negative residual cells.

J. Erlecke, I. Hartmann, M. Hoffmann, T. Kroll, H. Starke, A. Heller, A. Gloria, H.G. Sayer, T. Johannes, U. Claussen, T. Liehr, I.F. Loncarevic

A new chimerism analysis based on automated interphase fluorescence in situ hybridization (FISH) evaluation was established to detect residual cells after allogene sex-mismatched bone marrow or blood stem-cell transplantation.Cells of 58 patients were characterized as disease-associated due to presence of a bcr/abl-gene-fusion or a trisomy 8 and/or a simultaneous hybridization of gonosome-specific centromeric probes. The automatic slide scanning platform Metafer with its module MetaCyte was used to analyse 3,000 cells per sample. RESULTS: Overall 454 assays of 58 patients were analyzed. 13 of 58 patients showed residual recipient cells at one stage of more than 4% and 12 of 58 showed residual recipient cells less than 4%, respectively. As to be expected, patients of the latter group were associated with a higher survival rate (48 vs. 34 month). In only two of seven patients with disease-marker positive residual cells between 0.1-1.3% a relapse was observed. Besides, disease-marker negative residual cells were found in two patients without relapse at a rate of 2.8% and 3.3%, respectively. CONCLUSION: The definite origin and meaning of disease-marker negative residual cells is still unclear. Overall, with the presented automatic chimerism analysis of interphase FISH slides, a sensitive method for detection of disease-marker positive residual cells is on hand.

Mol Cytogenet, 2, 15

Application of molecular cytogenetic techniques to clarify apparentlybalanced complex chromosomal rearrangements in two patients withan abnormal phenotype: case report.

de Vree, Paula Jp, Marleen Eh Simon, van Dooren, Marieke F, Gerda Ht Stoevelaar, José Tw Hilkmann, Michel A Rongen, Gido Cm Huijbregts, Annemieke Jmh Verkerk, Pino J Poddighe

ABSTRACT: BACKGROUND: Complex chromosomal rearrangements (CCR) are rare cytogenetic findings that are difficult to karyotype by conventional cytogenetic analysis partially because of the relative low resolution of this technique. High resolution genotyping is necessary in order to identify cryptic imbalances, for instance near the multiple breakpoints, to explain the abnormal phenotype in these patients. We applied several molecular techniques to elucidate the complexity of the CCRs of two adult patients with abnormal phenotypes. RESULTS: Multicolour fluorescence in situ hybridization (M-FISH) showed that in patient 1 the chromosomes 1, 10, 15 and 18 were involved in the rearrangement whereas for patient 2 the chromosomes 5, 9, 11 and 13 were involved. A 250 k Nsp1 SNP-array analysis uncovered a deletion in chromosome region 10p13 for patient 1, harbouring 17 genes, while patient 2 showed no pathogenic gains or losses. Additional FISH analysis with locus specific BAC-probes was performed, leading to the identification of cryptic interstitial structural rearrangements in both patients. CONCLUSION: Application of M-FISH and SNP-array analysis to apparently balanced CCRs is useful to delineate the complex chromosomal rearrangement in detail. However, it does not always identify cryptic imbalances as an explanation for the abnormal phenotype in patients with a CCR.