Molecular Cytogenetics - Most accessed articles

Selection of single blastocysts for fresh transfer via standard morphology assessment alone and with array CGH for good prognosis IVF patients: results from a randomized pilot study

Zhihong Yang — 2012-05-02T00:00:00Z

Background: Single embryo transfer (SET) remains underutilized as a strategy to reduce multiple gestationrisk in IVF, and its overall lower pregnancy rate underscores the need for improvedtechniques to select one embryo for fresh transfer. This study explored use of comprehensivechromosomal screening by array CGH (aCGH) to provide this advantage and improvepregnancy rate from SET. Methods: First-time IVF patients with a good prognosis (age <35, no prior miscarriage) and normalkaryotype seeking elective SET were prospectively randomized into two groups: In Group A,embryos were selected on the basis of morphology and comprehensive chromosomalscreening via aCGH (from d5 trophectoderm biopsy) while Group B embryos were assessedby morphology only. All patients had a single fresh blastocyst transferred on d6. Laboratoryparameters and clinical pregnancy rates were compared between the two groups. Results: For patients in Group A (n = 55), 425 blastocysts were biopsied and analyzed via aCGH (7.7blastocysts/patient). Aneuploidy was detected in 191/425 (44.9%) of blastocysts in thisgroup. For patients in Group B (n = 48), 389 blastocysts were microscopically examined (8.1blastocysts/patient). Clinical pregnancy rate was significantly higher in the morphology +aCGH group compared to the morphology-only group (70.9 and 45.8%, respectively; p =0.017); ongoing pregnancy rate for Groups A and B were 69.1 vs. 41.7%, respectively (p =0.009). There were no twin pregnancies. Conclusion: Although aCGH followed by frozen embryo transfer has been used to screen at risk embryos(e.g., known parental chromosomal translocation or history of recurrent pregnancy loss), thisis the first description of aCGH fully integrated with a clinical IVF program to select singleblastocysts for fresh SET in good prognosis patients. The observed aneuploidy rate (44.9%)among biopsied blastocysts highlights the inherent imprecision of SET when conventionalmorphology is used alone. Embryos randomized to the aCGH group implanted with greaterefficiency, resulted in clinical pregnancy more often, and yielded a lower miscarriage ratethan those selected without aCGH. Additional studies are needed to verify our pilot data andconfirm a role for on-site, rapid aCGH for IVF patients contemplating fresh SET.

Exosome-delivered microRNAs of "chromosome 19 microRNA cluster" as immunomodulators in pregnancy and tumorigenesis

Jörn Bullerdiek — 2012-05-06T00:00:00Z

Background: Structural rearrangements of chromosomal band 19q13 are a non-random cytogenetic abnormality in thyroid adenomas and adenomatous goiters and lead to an expression of miRNAs of the chromosome 19 microRNA cluster C19MC. Normally, expression of these miRNAs is silenced except for embryonic stem cells and the placenta where they represent the majority of miRNAs not only in the trophoblast but also in exosomes derived from it.Presentation of the hypothesisWe have advanced the hypothesis that as part of the feto-maternal communication miRNAs of C19MC serve immunomodulatory functions in the placenta and confer a growth advantage to thyroid nodules by protecting them against autoimmune attacks. More precisely, the exosomes containing these miRNAs may specifically target immune cells in their local environment as well as systemically by transferring their cargo to recipient cells. Within these target cells the transferred miRNAs can interact with mRNAs of the recipient cells thereby suppressing their immune-specific functions.Testing the hypothesisExperiments used to demonstrate the immunomodulatory capacity of placenta-derived exosomes can be modified by transfecting the target cells with those miRNAs of C19MC represented in placental exosomes.Implications of the hypothesisMimics of C19MC-derived miRNAs might develop to useful drug candidates for the treatment of autoimmune disease as e.g. rheumatoid arthritis and Sjogren's syndrome and for the prevention of transplant rejection. In case of tumor entities with elevated expression of C19MC miRNAs these miRNAs may be interesting targets for treatment with appropriate antagonists.

Human interphase chromosomes: a review of available molecular cytogenetic technologies

Svetlana Vorsanova — 2010-01-11T00:00:00Z

Human karyotype is usually studied by classical cytogenetic (banding) techniques. To perform it, one has to obtain metaphase chromosomes of mitotic cells. This leads to the impossibility of analyzing all the cell types, to moderate cell scoring, and to the extrapolation of cytogenetic data retrieved from a couple of tens of mitotic cells to the whole organism, suggesting that all the remaining cells possess these genomes. However, this is far from being the case inasmuch as chromosome abnormalities can occur in any cell along ontogeny. Since somatic cells of eukaryotes are more likely to be in interphase, the solution of the problem concerning studying postmitotic cells and larger cell populations is interphase cytogenetics, which has become more or less applicable for specific biomedical tasks due to achievements in molecular cytogenetics (i.e. developments of fluorescence in situ hybridization -- FISH, and multicolor banding -- MCB). Numerous interphase molecular cytogenetic approaches are restricted to studying specific genomic loci (regions) being, however, useful for identification of chromosome abnormalities (aneuploidy, polyploidy, deletions, inversions, duplications, translocations). Moreover, these techniques are the unique possibility to establish biological role and patterns of nuclear genome organization at suprachromosomal level in a given cell. Here, it is to note that this issue is incompletely worked out due to technical limitations. Nonetheless, a number of state-of-the-art molecular cytogenetic techniques (i.e multicolor interphase FISH or interpahase chromosome-specific MCB) allow visualization of interphase chromosomes in their integrity at molecular resolutions. Thus, regardless numerous difficulties encountered during studying human interphase chromosomes, molecular cytogenetics does provide for high-resolution single-cell analysis of genome organization, structure and behavior at all stages of cell cycle.

The genome diversity and karyotype evolution of mammals

Alexander Graphodatsky — 2011-10-12T00:00:00Z

The past decade has witnessed an explosion of genome sequencing and mapping in evolutionary diverse species. While full genome sequencing of mammals is rapidly progressing, the ability to assemble and align orthologous whole chromosome regions from more than a few species is still not possible. The intense focus on building of comparative maps for companion (dog and cat), laboratory (mice and rat) and agricultural (cattle, pig, and horse) animals has traditionally been used as a means to understand the underlying basis of disease-related or economically important phenotypes. However, these maps also provide an unprecedented opportunity to use multispecies analysis as a tool for inferring karyotype evolution. Comparative chromosome painting and related techniques are now considered to be the most powerful approaches in comparative genome studies. Homologies can be identified with high accuracy using molecularly defined DNA probes for fluorescence in situ hybridization (FISH) on chromosomes of different species. Chromosome painting data are now available for members of nearly all mammalian orders. In most orders, there are species with rates of chromosome evolution that can be considered as 'default' rates. The number of rearrangements that have become fixed in evolutionary history seems comparatively low, bearing in mind the 180 million years of the mammalian radiation. Comparative chromosome maps record the history of karyotype changes that have occurred during evolution. The aim of this review is to provide an overview of these recent advances in our endeavor to decipher the karyotype evolution of mammals by integrating the published results together with some of our latest unpublished results.

Analysis of ZAP70 expression in adult acute lymphoblastic leukaemia by real time quantitative PCR

Geothy Chakupurakal — 2012-05-01T00:00:00Z

Background: ZAP70 gene expression is associated with poor prognosis in B-cell lymphoproliferativedisorders especially chronic lymphocytic leukaemia (CLL) but its role in adult B-ALL hasnot been established. On diagnostic samples from 76 patients with adult ALL (65 with BALLand 11 with T-ALL) ZAP70 mRNA expression levels were studied by real timequantitativePCR (RT-qPCR) analysis.FindingsA broad distribution of ZAP70 expression was observed in ALL, ranging from 0.002 to 5.3fold that of the ZAP70 positive Jurkat reference cell line. No association was observedbetween expression levels and the presence of specific cytogenetic abnormalities. Five cases,including one case of T-ALL, had ZAP70 expression above the level of the Jurkat referencecell line. Conclusions: Our results confirm the frequent expression of ZAP70 in adult ALL. Limited comparisonsmade did highlight poor-risk patients with high ZAP70 expression, but due to lack of clinicalinformation on patient samples we were unable to directly assess the impact on diseaseprognosis. ZAP-70 may be an important laboratory assay in adult ALL and further studies arewarranted to study a potential correlation with cytogenetic and other genetic markers.

Chromosomal mosaicism goes global

Ivan Iourov — 2008-11-25T00:00:00Z

Intercellular differences of chromosomal content in the same individual are defined as chromosomal mosaicism (alias intercellular or somatic genomic variations or, in a number of publications, mosaic aneuploidy). It has long been suggested that this phenomenon poorly contributes both to intercellular (interindividual) diversity and to human disease. However, our views have recently become to change due to a series of communications demonstrated a higher incidence of chromosomal mosaicism in diseased individuals (major psychiatric disorders and autoimmune diseases) as well as depicted chromosomal mosaicism contribution to genetic diversity, the central nervous system development, and aging. The later has been produced by significant achievements in the field of molecular cytogenetics. Recently, Molecular Cytogenetics has published an article by Maj Hulten and colleagues that has provided evidences for chromosomal mosaicism to underlie formation of germline aneuploidy in human female gametes using trisomy 21 (Down syndrome) as a model. Since meiotic aneuploidy is suggested to be the leading genetic cause of human prenatal mortality and postnatal morbidity, these data together with previous findings define chromosomal mosaicism not as a casual finding during cytogenetic analyses but as a more significant biological phenomenon than previously recognized. Finally, the significance of chromosomal mosaicism can be drawn from the fact, that this phenomenon is involved in genetic diversity, normal and abnormal prenatal development, human diseases, aging, and meiotic aneuploidy, the intrinsic cause of which remains, as yet, unknown.

BCR-JAK2 fusion as a result of a translocation (9;22)(p24;q11.2) in a patient with CML-like myeloproliferative disease

Mohamed Elnaggar — 2012-05-01T00:00:00Z

Translocation (9;22)(q34;q11.2) resulting in BCR/ABL1 fusion at the molecular level is thehallmark of chronic myelogenous leukemia (CML). Variants of the Philadelphia translocationand complex translocations involving BCR have been reported in myeloproliferativedisorders (MPD). A rare translocation, t(9;22)(p24;q11.2), resulting in a novel BCR-JAK2fusion has been reported in a handful of cases of CML and acute myelogenous leukemia(AML). We present clinical-pathological and cytogenetic evaluation of a patient withPhiladelphia-chromosome negative CML/MPD harboring a t(9;22)(p24;q11.2) resulting inBCR-JAK2 fusion. Fluorescence in situ hybridization and molecular characterization of thetranslocation confirmed a BCR-JAK2 fusion and helped delineate the breakpoints upstreamof exon 1 of minor cluster region of BCR gene and likely intron 18 of the JAK2 gene,resulting in an in-frame transcript This case provides convincing support, along with twoprevious case-reports, for a role for activation of the Janus kinase 2 in evolution ofmyeloproliferative disease. The recurrent, albeit rare, nature of the breakpoints within BCRand JAK2 suggests a potential new diagnostic target that should be interrogated in PhnegativeCML/MPD patients.

Molecular cytogenetic characterization of undifferentiated embryonal sarcoma of the liver: a case report and literature review

Xiaoxia Hu — 2012-05-03T00:00:00Z

Undifferentiated embryonal sarcoma of the liver (UESL) represents a heterogeneous group of tumors derived from mesenchymal tissues. Earlier cytogenetic studies in limited cases demonstrated that UESL is associated with a recurrent translocation t(11;19)(q11;q13.3-q13.4) or add(19)(q13.4). In this report, we present our array comparative genomic hybridization (aCGH), fluorescence in situ hybridization (FISH) findings, and a missense mutation of TP53 gene by DNA sequencing in a 19-year-old patient with UESL. The data were compared to laboratory findings reported by previous studies.

Deletions in chromosome 6p22.3-p24.3, including ATXN1, are associated with developmental delay and autism spectrum disorders

Patricia Celestino-Soper — 2012-04-05T00:00:00Z

Interstitial deletions of the short arm of chromosome 6 are rare and have been associated with developmental delay, hypotonia, congenital anomalies, and dysmorphic features. We used array comparative genomic hybridization in a South Carolina Autism Project (SCAP) cohort of 97 subjects with autism spectrum disorders (ASDs) and identified an ~ 5.4 Mb deletion on chromosome 6p22.3-p23 in a 15-year-old patient with intellectual disability and ASDs. Subsequent database queries revealed five additional individuals with overlapping submicroscopic deletions and presenting with developmental and speech delay, seizures, behavioral abnormalities, heart defects, and dysmorphic features. The deletion found in the SCAP patient harbors ATXN1, DTNBP1, JARID2, and NHLRC1 that we propose may be responsible for ASDs and developmental delay.

A novel five-way translocation t(7;11;9;22;9)(q22;q13;q34;q11.2;q34) involving Ph chromosome in a patient of chronic myeloid leukemia: a case report

Sho Yokota — 2012-05-01T00:00:00Z

About 5-10 % of chronic myelogenous leukemia (CML) patients show variant Philadelphia (Ph) translocations. The formation mechanisms and clinical significance of variant Ph translocations remain unclear. We report a CML case with a novel five-way complex translocation. Although the result of initial G-banding was 46,XY,t(7;11;9)(q22;q13;q34),t(9;22)(q34;q11.2), fluorescence in situ hybridization (FISH) demonstrated t(7;11;9;22;9)(q22;q13;q34;q11.2;q34) consisting of sequential rearrangements involving five chromosomes. The patient was successfully treated by imatinib and obtained a major molecular response. To our knowledge, this is the tenth CML case with a complicated Ph translocation involving five chromosomes and the third one treated by imatinib. Good response with imatinib therapy suggested that a single-event rearrangement was involved in the chromosomal changes.