Biomedical subjects

G H Vance

Publications and source records attributed to G H Vance.

At least 19 recordsLinked to original sources

PubMed2006

Redefining the risks of prenatally ascertained supernumerary marker chromosomes: a collaborative study.

BACKGROUND: A marker chromosome is defined as a structurally abnormal chromosome that cannot be identified by routine cytogenetics. The risk for phenotypic abnormalities associated with a marker chromosome depends on several factors, including inheritance, mode of ascertainment, chromosomal origin, and the morphology, content, and structure of the marker. METHODS: to understand the karyotype-phenotype relationship of prenatally ascertained supernumerary de novo marker chromosomes, we combined data from prenatal cases obtained from 12 laboratories with those from studies in the literature. We were able to obtain cytogenetic and phenotypic data from 108 prenatally ascertained supernumerary de novo marker chromosomes to refine the phenotypic risk associated with these markers. Because of the growing number of cases and because more techniques are available to delineate marker morphology, we have been able to group risk estimates into subcategories, such as by marker type and whether there are ultrasound abnormalities. RESULTS: If a de novo supernumerary marker chromosome is found prenatally, our data suggest there is a 26% risk for phenotypic abnormality when there is no other information defining the marker (such as chromosomal origin or information about the existing phenotype). However, if high resolution ultrasound studies are normal, this risk reduces to 18%. CONCLUSIONS: Our findings strongly support the value of additional genetic studies for more precisely defining the risk in individual cases involving marker chromosomes.

Chromosome Aberrations↗

PubMed2005

Genetic diagnosis of PLP gene duplications/deletions in patients with Pelizaeus-Merzbacher disease.

Genetic diagnosis of PLP gene duplications/deletions in patients with Pelizaeus-Merzbacher disease.PMD is an X-linked recessive disorder due to a proteolipid protein (PLP) deficiency. Duplications of PLP gene were shown to be the principle cause of the disorder, accounting for an estimated 50-70% of cases. To define a simple and reliable method for genetic diagnosis of PMD, a group of 42 patients with clinical manifestation of PMD was analyzed by means of real-time quantitative PCR. Parallel fluorescence in situ hybridization (FISH) analysis was performed on the same group of patients. Real-time PCR found seventeen samples had increased gene dosage, whereas FISH detected sixteen duplicated samples. Both methods identified a sample with PLP gene deletion. Our results indicate that real-time PCR is a sensitive and reliable method for the detection of gene duplications/deletions. We further discussed the advantages and limitations of each method in clinical diagnosis of PMD.

DNA Mutational Analysis↗

PubMed2002

HER-2/neu expression in germ cell tumours.

AIMS: To determine the rate of HER-2/neu positivity of germ cell tumours by immunohistochemistry (IHC) and by fluorescence in situ hybridisation (FISH). PATIENTS/METHODS: Ninety six archival, paraffin wax embedded pathology specimens were chosen from four groups of germ cell tumours. IHC for HER-2/neu was performed with the HercepTest kit; FISH analysis was performed with the INFORM assay and confirmed with a centromere 17 probe. RESULTS: Twenty two of 96 specimens overexpressed the HER-2/neu protein when measured by IHC. Only three specimens showed HER-2/neu gene amplification by FISH. There was no correlation between the results obtained by IHC and FISH. CONCLUSIONS: The lack of concordance between IHC and FISH makes it unlikely that overexpression of the HER-2/neu protein in germ cell tumours is of prognostic or therapeutic relevance. Because of the low rate of HER-2/neu gene amplification in germ cell tumours, a clinical trial of trastuzumab treatment in patients with germ cell tumours is not warranted.

Gene Expression↗

PubMed2001

Improvements in cytogenetic slide preparation: controlled chromosome spreading, chemical aging and gradual denaturing.

BACKGROUND: Metaphase spreading is an essential technique for clinical and molecular cytogenetics. Results of classical banding techniques as well as complex fluorescent in situ hybridization (FISH) applications, such as comparative genomic hybridization (CGH) or multiplex FISH (M-FISH), are greatly influenced by the quality of chromosome spreading and pretreatment of the slide prior to hybridization. Materials and Methods Using hot steam and a metal plate with a temperature gradient across its surface, a reproducible protocol for slide preparation, aging, and hybridization was developed. RESULTS: This protocol yields good chromosome spreads from even the most difficult cell suspensions and is unaffected by the environmental conditions. Chromosome spreads were suitable for both banding and FISH techniques common to the cytogenetic laboratory. Chemical aging is a rapid slide pretreatment procedure for FISH applications, which allows freshly prepared cytogenetic slides to be used for in situ hybridization within 30 min, thus increasing analytical throughput and reducing benchwork. Furthermore, the gradually denaturing process described allows the use of fresh biologic material with optimal FISH results while protecting chromosomal integrity during denaturing. CONCLUSION: The slide preparation and slide pretreatment protocols can be performed in any laboratory, do not require specialized equipment, and provide robust results.

Cell Line↗

PubMed2001

Distal 13q Deletion Syndrome and the VACTERL association: case report, literature review, and possible implications.

We present a case of a child with del(13) (q31.1qter), VACTERL association, and penoscrotal transposition. Deletion of the distal long arm of chromosome 13 is associated with variable phenotypes. These phenotypes are divided into three clusters; each cluster represents a specific deleted segment of 13q. Individuals with deletions of a critical region at 13q32 have multiple congenital malformations that include components of the VACTERL association. Our patient had all six manifestations of VACTERL association. In addition, he had complete penoscrotal transposition, a unique malformation reported rarely in VACTERL association and only twice previously in deletion of distal 13q. We reviewed all reported cases of distal 13q deletions to date. Of these 137 patients, 15 could be classified into the VACTERL association. Ours was the only patient with distal 13q deletion and all VACTERL association features and also the only one with tracheoesophageal fistula. Neither holoprosencephaly nor the other central nervous system malformations that have been seen in individuals with distal 13q deletions were apparent in him. The patient presented here appears to be unique among individuals with distal 13q deletion. His cluster of malformations strengthens the argument that distal 13q deletion is a cause for VACTERL association, and that this causal relationship implies a syndromic form of VACTERL. In addition, this case and those ascertained from the literature suggest that penoscrotal transposition should be considered part of both the distal 13q-deletion syndrome and some forms of VACTERL association.

Abnormalities, Multiple↗

PubMed2001

Cytogenetic analysis and construction of a BAC contig across a common neocentromeric region from 9p.

Over 40 cases of neocentric marker chromosomes, without detectable alpha-satellite DNA, have been reported. Although these have originated from many different chromosomes, a few of these chromosomes have been involved in multiple cases of marker formation. In this study, two different markers originating from the short arm of chromosome 9 were analyzed, identifying a common neocentromeric region. A bacterial artificial chromosome (BAC) contig extending over more than 900 kb has been assembled across this neocentromeric region. Fluorescent in situ hybridization and immunofluorescence assays (CENP-C and CENP-E) have localized the neocentromere to a 500 kb region. Preliminary analysis of DNA sequences in this neocentromere revealed a highly AT-rich region, which also has an increase in the level of retroviral elements compared with the average levels in the genome.

Animals↗

PubMed2001

Small marker chromosome identification in metaphase and interphase using centromeric multiplex fish (CM-FISH).

Multicolor karyotyping procedures, such as multiplex fluorescence in situ hybridization (M-FISH), spectral karyotyping, or color-changing karyotyping, can be used to detect chromosomal rearrangements and marker chromosomes in prenatal diagnosis, peripheral blood cultures, leukemia, and solid tumors, especially in cases where G-banding is not sufficient. A regular M-FISH analysis requires relatively large amounts of labeled DNA (microgram quantities), is not informative in interphase nuclei, hybridization can take up to 2 to 3 days, and unlabeled human chromosome-painting probes are not available commercially. Unique probes (plasmids, PAC), specific for centromeric or subtelomeric chromosomal regions, can replace the painting probes in M-FISH to address specific issues, such as the identification of marker chromosomes and aneuploidies. A set of plasmid probes carrying repetitive sequences specific for the alpha-satellite region of all human chromosomes were combined in a metaphase assay and an interphase assay, allowing identification of aneuploidies in one hybridization step, on a single cytogenetic slide. The fluorophore-dUTP and the labeled antibodies required to label and detect the DNA probes can be prepared in any laboratory. All DNA probes can be easily isolated and labeled using common molecular cytogenetic procedures. Because of the repetitive nature of the probes, hybridization time is short, usually less than 1 hour, and the analysis can be performed with nonspecialized image-processing software.

Aneuploidy↗

PubMed2001

Cryptic translocation identification in human and mouse using several telomeric multiplex fish (TM-FISH) strategies.

Experimental data published in recent years showed that up to 10% of all cases of mild to severe idiopathic mental retardation may result from small rearrangements of the subtelomeric regions of human chromosomes. To detect such cryptic translocations, we developed a "telomeric" multiplex fluorescence in situ hybridization (M-FISH) assay, using a set of previously published and commercially available subtelomeric probes. This set of probes includes 41 cosmid/PAC/P1 clones located from less than 100 kilobases to approximately 1 megabase from the end of the chromosomes. Similarly, a published mouse probe set, comprised of BACs hybridizing to the closest known marker toward the centromere and telomere of each mouse chromosome, was used to develop a mouse-specific "telomeric" M-FISH. Three different combinatorial labeling strategies were used to simultaneously detect all human subtelomeric regions on one slide. The simplest approach uses only three fluors and can be performed in laboratories lacking sophisticated imaging equipment or personnel highly trained in cytogenetics. A standard fluorescence microscope equipped with only three filters is sufficient. Fluor-dUTPs and labeled probes can be custom made, thus dramatically reducing costs. Images can be prepared using imaging software (Adobe Photoshop) and analysis performed by simple visual inspection.

Animals↗

PubMed2001

Costimulatory molecules in the developing human gastrointestinal tract: a pathway for fetal allergen priming.

BACKGROUND: Antigen-specific responses can be detected in umbilical cord blood mononuclear cells. The fetal immune system must therefore attain a level of maturity compatible with the initiation of such responses as well as be exposed to antigen. OBJECTIVE: We sought to assess the expression of costimulatory molecules in fetal gut and the presence of cytokines in amniotic fluid at this time as a preliminary analysis of the suitability of the fetal gut as a site of antigen priming during intrauterine life. METHODS: Human fetal gut was analyzed for cells expressing costimulatory molecules through use of immunohistochemistry. Amniotic fluid was studied by ELISA, for cytokines regulating the nature of the response, and as a source of the common dietary antigen ovalbumin. RESULTS: MHC class II--positive cells were abundant over the period examined (11-24 weeks of gestation), other surface antigens showing spatial and temporal variation in expression. From 11 to 14 weeks of gestation, CD68-positive and CD40-positive cells, like MHC class II--positive cells, were present throughout the lamina propria; few CD3-positive cells (T cells) were observed. With the emergence of lymphoid aggregates (14-16 weeks), CD83-positive cells (dendritic cells) and CD20-positive cells (B cells) could be detected in fetal gut; however, expression was restricted to the lymphoid aggregates. In contrast, MHC class II, CD40, and CD68 continued to be expressed in the lamina propria. CD28-positive cells were also evident from 14 weeks of gestation, occurring throughout the lamina propria and lymphoid aggregates; this corresponded to the increasing numbers of CD3-positive cells. The occasional CD86-positive, CD40L-positive, or CTLA4-positive cell could be seen in or around lymphoid aggregates after 14 weeks of gestation. Lymphoid follicles forming after 16 weeks of gestation contained MHC class II--positive, CD83-positive, CD20-positive, CD40-positive, CD86-positive, CD3-positive, CD28-positive, CD40L-positive, and CTLA4-positive cells. MHC class II--positive, CD40-positive, CD68-positive, CD3-positive, and CD28-positive cells continued to be present in the lamina propria at this time. At all times studied, CD14 was not expressed in the lamina propria or lymphoid follicles. Prostaglandin E(2), TGF beta(1), and IL-10 dominated the amniotic fluid cytokine milieu, and ovalbumin was also detectable in amniotic fluid from 3 of 26 women who had detectable circulating levels. CONCLUSION: Of the costimulatory molecules studied, CD40 was the most abundant. However, both of the ligand families studied (CD40-CD40L and CD86-CD28/CD152) could provide the costimulatory signals required for the initiation of antigenspecific reactivity in the gastrointestinal tract of the human fetus as early as 16 weeks of gestation. The cytokine milieu would favor the development of T(H)2-type reactivity to antigens, such as ovalbumin, that are present at this time.

Abatacept↗

PubMed2000

Detection of house-dust-mite allergen in amniotic fluid and umbilical-cord blood.

Mononuclear cells in umbilical-cord blood display allergen-specific reactivity, but how allergen exposure occurs in utero is unknown. We investigated the presence of a common inhalant allergen (Der p 1), to which mothers are exposed throughout pregnancy, by ELISA in matched maternal blood and amniotic fluid samples at 16-17 weeks of gestation, and in matched maternal and umbilical-cord blood at term (> or =37 weeks of gestation). Der p 1 was detectable in 24 of 43 amniotic fluid samples where it was also present in maternal blood, and in 15 of 24 cord-plasma samples at significantly higher concentrations than in the maternal plasma (p=0.022). The detection of Der p 1 in the amniotic fluid and the fetal circulation provides direct evidence of transamniotic and transplacental allergen exposure.

Amniotic Fluid↗

PubMed2000

Pre-natal sensitization in humans.

Allergy has a very strong hereditary component but even in identical twins, concordance for the development of allergic disease can be as low as 50%. This suggests that there is a very strong environmental influence on manifestations of sensitization. To what extent environment might have an influence on the ontogeny of sensitization antenatally has hitherto not been a focus of much research. However, circumstantial evidence suggests that this may be important.

Allergens↗

PubMed1999

Detection of monosomy 7 in bone marrow by fluorescence in situ hybridization. A study of Fanconi anemia patients and review of the literature.

Monosomy 7 is frequently found in the bone marrow of patients with Fanconi anemia (FA), marrow myelodysplasia, or acute myelogenous leukemia and is associated with poor prognosis. In our laboratory, cytogenetic analysis of bone marrow from an FA patient found 2 of 30 cells with monosomy 7, but the results of fluorescence in situ hybridization (FISH) indicated that 83 of 207 cells (40%) had monosomy 7. FISH was then used to analyze two earlier samples from the index case, neither of which had monosomy 7 as determined by standard cytogenetics. The FISH analysis determined that the first sample, taken 19 months earlier, had 8 of 200 cells (4%) with monosomy 7 and the second sample. taken 7 months later, contained 43 of 200 cells (21.5%) with monosomy 7. These results indicate a slow evolution toward monosomy 7 in the patient's bone marrow. Standard metaphase chromosome analysis represents only spontaneously dividing cells, leading us to hypothesize that FISH was detecting monosomy 7 in nondividing cells and that it might be useful in the early detection of abnormal clones. To test this hypothesis, FISH was performed on 13 bone marrow samples from nine patients with FA who did not exhibit monosomy 7 by cytogenetic analysis. Monosomy 7 was detected in 3.44% of nuclei in FA patients and in 3% of nuclei in normal controls. To date, none of these nine FA patients have developed monosomy 7 or leukemia. They are being monitored by standard cytogenetics and by FISH to determine whether monosomy 7 develops and whether it can be detected by FISH prior to its detection by standard cytogenetics. As standard practice, we have adopted FISH analysis for monosomy 7 in all patients with FA.

Adolescent↗

PubMed1999

Extensive analysis of mosaicism in a case of Turner syndrome: the experience of 287 cytogenetic laboratories. College of American Pathologists/American College of Medical Genetics Cytogenetics Resource Committee.

OBJECTIVE: To assemble and interpret karyotype data provided as part of the College of American Pathologists/American College of Medical Genetics Cytogenetics Proficiency Testing Program. DATA SOURCES, EXTRACTION, AND SYNTHESIS: The Cytogenetics Resource Committee requested data on all cells analyzed in a 1994 whole-blood specimen challenge. In that study, 287 participating laboratories analyzed a total of 14297 cells derived from a sample drawn from an adult donor with Turner syndrome. This individual had previously been found to have mosaicism, including cell lines with X structural anomalies along with monosomy X, making this an excellent challenge for a multicenter cytogenetic survey. RESULTS AND CONCLUSIONS: Analysis of the data from this extensive study revealed mosaicism of up to 10 different sex chromosome complements involving the X chromosome with and without a small ring X or a derivative X chromosome. In the routine cytogenetic analysis performed by the participating laboratories, cell lines observed, in decreasing order of prevalence, included 45,X (n = 8357 cells), 46,X,r(X) (n = 3597), 46,X,der(X)t(X;X) (n = 2237), 46,XX (n = 93), 47,X,r(X),r(X) (n = 5), 47,X,der (X)t(X;X),der(X)t(X;X) (n = 3), 47,XX,r(X) (n = 2), and one observation each of 47,XX,der(X)t(X;X), 47,X,der(X)t (X;X),r(X), and 47,XXX. Our molecular cytogenetic data, as well as detailed analysis of G-banded chromosomes, suggest the nomenclature for these 2 abnormal X chromosomes as r(X)(p11.3q21.3) and der(X)t(X;X)(p11.3;q21.3), and we discuss models for the concomitant formation of these 2 entities. Both the degree of analysis and the extensive mosaicism that was discovered in this study are exceptional, and similar reported cases as well as possible mechanisms for the observed X chromosome instability are reviewed.

Adult↗

PubMed1999

De novo 10q22 interstitial deletion.

We describe a 4 month old male with a de novo interstitial deletion of chromosome 10q22. His clinical features included growth deficiency, developmental delay, ocular hypertelorism, posteriorly rotated ears, retrognathia, and fifth finger clinodactyly. He later developed dental lamina cysts of the alveolar ridge. To our knowledge, this is the first reported case of an interstitial deletion of 10q22.

Abnormalities, Multiple↗

PubMed1998

Characterization of multiple 12p rearrangements in testicular germ cell tumor cell line 833K and its subclone 64CP by chromosome microdissection.

Rearrangements of chromosome arm 12p are known to be common in germ cell tumors (GCT). Previous studies, using fluorescence in situ hybridization (FISH) with a whole chromosome 12 painting probe, showed unusual distributions of chromosome 12-derived chromatin in GCT cell line 833K and its cisplatin-resistant subclone, 64CP, located next to AgNOR (silver staining nucleolus organizer regions), some of which were ectopic. In this study, the ectopic stalk regions were shown by FISH to be composed of 18s and 28s rDNA, but were flanked by beta-satellite DNA, which may form a barrier around the rDNA. In order to determine the specific origins of the rearranged chromosome 12 segments, three different derived chromosome 12 regions were isolated from 64CP, using chromosomal microdissection. The microdissected fragments were labeled and hybridized by FISH to normal human chromosomes. All three segments localized to distal 12p; 12p12-->12pter, but with apparently different breakpoints for each segment. Furthermore, three-color FISH experiments with 12p band-specific probes demonstrated that the derivative chromosome 12 regions in 833K also originate from distal 12p (12p12-->p13). These sequences now can be evaluated for degree of overlap or common breakpoints which may be of significance in the development or progression of GCT.

Chromosome Aberrations↗

PubMed1998

A multicenter investigation with interphase fluorescence in situ hybridization using X- and Y-chromosome probes.

Twenty-six laboratories used X and Y chromosome probes and the same procedures to process and examine 15,600 metaphases and 49,400 interphases from Phaseolus vulgaris-leucoagglutinin (PHA)-stimulated lymphocytes. In Part I, each laboratory scored 50 metaphases and 200 interphases from a normal male and a normal female from its own practice. In Part II, each laboratory scored 50 metaphases and 200 interphases on slides prepared by a central laboratory from a normal male and a normal female and three mixtures of cells from the male and female. In Part III, each laboratory scored 50 metaphases (in samples of 5, 10, 15, and 20) and 100 interphases (in samples of 5, 10, 15, 20, and 50) on new, coded slides of the same specimens used in Part II. Metaphases from male specimens were scored as 98-99% XY with no XX cells, and 97-98% of interphases were scored as XY with 0.04% XX cells. Metaphases from female specimens were scored as 96-97% XX with 0.03% XY cells, and 94-96% of interphases were scored as XX with 0.05% XY cells. Considering the data as a model for any probe used with fluorescence in situ hybridization (FISH), a statistical approach assessing the impact of analytical sensitivity on the numbers of observations required to assay for potential mosaicisms and chimerisms is discussed. The workload associated with processing slides and scoring 50 metaphases and 200 interphases using FISH averaged 27.1 and 28.6 minutes, respectively. This study indicates that multiple laboratories can test/develop guidelines for the rapid, efficacious, and cost-effective integration of FISH into clinical service.

Cytogenetics↗

PubMed1998

Molecular cytogenetic analysis of patients with holoprosencephaly and structural rearrangements of 7q.

The holoprosencephaly (HPE) sequence is a malformation complex with abnormal midline cleavage of the embryonic forebrain. HPE is genetically heterogeneous with at least 6 different chromosome regions containing genes involved in the expression of the phenotype. HPE3, recently identified as the human Sonic hedgehog gene, is localized to 7q36. We have used fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR) amplification in 5 cell lines from patients with HPE (3 cases), HPE and sacral agenesis (1 case), and microcephaly (1 case) to further define the structural rearrangements of the long arm of chromosome 7 in each case. All cell lines demonstrated loss of material in the critical region of HPE3 at band 7q36, which includes the Sonic hedgehog gene. We report here the analysis of these patient cell lines.

Cell Line↗

PubMed1998

Triple-color FISH analysis of 12p amplification in testicular germ-cell tumors using 12p band-specific painting probes.

Forty-nine surgical specimens and nine germ cell tumor lines were analyzed by triple-color FISH using microdissected probes for the cytogenetic bands of chromosome arm 12p (12p11.2, p12, and p13). FISH analysis demonstrated amplification of material from all three bands in all tumors. This amplification was in the form of increased copy number of 12p or i(12p) and/or 12p amplified regions (AMP12p). The number of copies of 12p was variable (4-11 copies) from case to case but tended to remain relatively constant in all clones of the same tumor, even when the amplification took the form of an amplified region composed of 12p material. In tumors with multiple clones, i(12p) and AMP12p were never found in the same cell. No correlation was found between 12p copy number and tumor type. We describe, for the first time, a relative overrepresentation of 12p13 or 12p12-p13 regions in six tumors (two surgical samples and four cell lines), either as "partial 12p" (five cases) or within a 12p amplified region (one case). The ubiquitous amplification of all three 12p bands in germ-cell tumors supports the hypothesis that 12p harbors more than one gene important for oncogenesis of adult male germ-cell tumors, and that these genes may be located in different areas of 12p.

Adult↗