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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
101

Microarray-Based Comparative Genomic Hybridization in Neurofibromatoses and DiGeorge Syndrome

Mantripragada, Kiran K. January 2005 (has links)
Microarray-based comparative genomic hybridization (array-CGH) has emerged as a versatile platform with a wide range of applications in molecular genetics. This thesis focuses on the development of array-CGH with a specific aim to approach disease-related questions through improved strategies in array construction and enhanced resolution of analysis. In <b>paper I</b>, we applied an array covering 11 Mb of 22q, encompassing the NF2 locus, for deletion detection in sporadic schwannoma. Hemizygous deletions and tumor heterogeneity were identified. Array-CGH was established as a reliable platform for detection of DNA dosage alterations. <b>Paper II</b> described the construction of the NF2 gene-specific microarray for high-resolution scanning of deletions in the NF2 locus. We report a novel PCR-based non-redundant strategy for microarray fabrication, which considerably improved the sensitivity and reliability of deletion detection. <b>Paper III</b> reported the first tiling-path array comprehensively covering a human chromosome. The usefulness of the 22q-array was demonstrated by applying it to detect DNA dosage-alterations in 22q-associated disorders. In <b>paper IV</b>, we optimized array-CGH protocols for deletion detection in 22q11 deletion-syndrome. We showed that genomic and cDNA clones are not optimal for analysis of 22q11 locus and that PCR-based non-redundant strategy is reliable for deletion detection in such regions. In <b>paper V</b>, we utilized the 22q-array for understanding the genetic basis of schwannomatosis. Two commonly deleted regions were identified within the IGL and the GSTT1/CABIN1 loci. Further investigations using high-resolution arrays, bioinformatic analysis and mutational screening were performed. Missense mutations, specific to the schwannomatosis- and NF2 samples, were identified in the CABIN1 gene. <b>Paper VI</b> described the first array-CGH study for comprehensive and high-resolution profiling of deletions spanning the 17q11 locus. Both typical and atypical deletions were identified in NF1 samples. Bioinformatic analysis revealed novel segmental duplications, which can potentially mediate 17q11 deletions.
102

Development and Application of Human Chromosome 22 Genomic Microarray : Chromosome 22-Associated Disorders Analyzed by Array-Based Comparative Genomic Hybridization

Benetkiewicz, Magdalena January 2006 (has links)
The array-based form of comparative genomic hybridization (array-CGH) is a new methodology that has shown to be of significant importance. This thesis focuses on the development of array-CGH with the aim to define candidate regions/genes on chromosome 22 in a wide spectrum of cancer-related conditions. In <b>paper I</b>, we developed and applied the first comprehensive genomic microarray, representing human chromosome 22, for analysis of DNA copy number. Using this array-based approach, we identified gene copy number alterations, including heterozygous/homozygous deletions, amplifications, IGLV/IGLC locus instability and the breakpoints of imbalanced translocation, in several 22q-associated disorders. In <b>paper II</b>, we applied the same array to perform DNA copy number profiling of a series of ovarian carcinoma. cDNA arrays were also used in this study to correlate gene expression levels with DNA-copy number. In the course of this analysis, we determined a small 3.5 Mb candidate 22q telomeric region and suggested a number of specific candidate genes. <b>Paper III</b> described the comprehensive and high-resolution analysis of chromosome 22 in a large set of various stage breast cancers. Multiple distinct patterns of genetic aberrations were observed. The smallest identified candidate locus was 220 kb in size and mapped to a gene-rich region in the vicinity of telomere of 22q. Intriguing result of this study was the detection of high frequency (26.6%) of intra-tumoral clonal variation in gene copy number profiles, which should be viewed as a high number, considering that we study in detail only a single human chromosome. In <b>paper IV</b>, we profiled a series of 28 Wilms tumor samples using 22q-array in order to assess specific regions affected with DNA dosage-alterations. The distribution of aberrations defined a complex amplifier genotype and delimited two tumor suppressor/oncogene candidate loci. These results open up for several avenues for continued research of these tumor forms. These findings also demonstrate the power of array-CGH in the precise determination of minute DNA copy number alterations and strengthen the notion that further studies, preferentially in the context of the entire human genome, are needed.
103

Analysis of Genetic Alterations in Patients Affected with Neurofibromatosis Type 2 and its Associated Tumors

Hansson, Caisa Marie January 2006 (has links)
Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder with the clinical hallmark of bilateral vestibular schwannomas (VS). Patients affected by a severe NF2 phenotype also presents with peripheral schwannomas, meningiomas and ependymomas. The closely related disorder schwannomatosis also displays multiple schwannomas, but never VS. Mutation screening of the NF2 gene in the above mentioned tumors did not identify mutations in numerous of cases. We analyzed the DNA sequence covering the NF2 locus in order to identify evolutionarily conserved non-genic sequences (CNGs) with unknown regulatory function (paper I). The aim was to analyze CNGs for mutations in DNA derived from patients affected by NF2 associated tumors. During mutation analysis of the coding part of NF2 and within the CNGs defined in paper I, were mutations detected in 39% of sporadic meningiomas (paper II). Two candidate regions were identified on 22q using array-CGH. Methylation profiling did not identify methylation of the NF2 promoter in these tumors. Sporadic schwannomas were profiled for CNV using a 22q genomic array in the search for putative gene(s) that in addition to NF2 could be involved in the development of schwannoma and/or schwannomatosis (paper III). The predominant aberration identified was monosomy 22. Terminal and interstitial deletions encompassing the NF2 gene were detected in tumor DNA and eight loci affected by CNV in constitutional DNA. Some of these CNVs are unlikely to be phenotypically neutral, considering their size and gene content. Two schwannomatosis candidate regions were identified on 22q using array-CGH (paper IV). These regions were further characterized by a PCR-product based array with higher resolution. Rearrangements of the immunoglobulin lambda (IGL) locus detected were restricted to schwannomatosis patients. In the second candidate region spanning GSTT1 and CABIN1 genes, was frequent copy number polymorphism at the GSTT1 locus identified. We further describe missense mutations in the CABIN1 gene, making this gene a plausible candidate which may contribute to the pathogenesis of these disorders.
104

Etude des relations génotype/phénotype dans le rétinoblastome

Castéra, Laurent 22 November 2012 (has links) (PDF)
Le rétinoblastome est une tumeur rare qui touche la rétine du jeune enfant. L'inactivation bi-allélique du gène RB1 est à l'origine du développement tumoral. RB1 est le premier gène suppresseur de tumeur qui ait été identifié et la prédisposition au rétinoblastome constitue un véritable paradigme de la prédisposition aux cancers. Dans les formes non prédisposées génétiquement, les deux mutations apparaissent dans une cellule rétinienne unique ; le rétinoblastome est alors unilatéral. Dans les formes à prédisposition génétique, la première mutation est constitutionnelle et la deuxième est somatique. La mutation constitutionnelle est une néo-mutation pré- ou post- zygotique dans les formes sporadiques, alors qu'elle est héritée dans les formes familiales. Dans les formes avec prédisposition génétique, le diagnostic est plus précoce que dans les formes sans prédisposition et la bilatérisation du rétinoblastome est généralement la règle. Néanmoins, de rares familles présentent une pénétrance réduite et une variabilité phénotypique se traduisant par la coexistence de patients atteints de rétinoblastome bilatéral ou unilatéral, d'apparentés porteurs sains et d'apparentés présentant des rétinomes. Les mécanismes responsables de la variabilité phénotypique intrafamiliale sont inconnus et l'existence de facteurs génétiques modulant le phénotype tumoral est probable.L'origine de la variabilité de l'expression phénotypique du rétinoblastome peut être la résultante (i) de l'existence de mutations en mosaïque, (ii) de mutations de RB1 et (iii) de facteurs modificateurs génétiques indépendants du locus de RB1. Trois axes distincts et originaux basés sur ces origines possibles de variabilité phénotypique ont été développés pour caractériser les relations génotype/phénotype dans le rétinoblastome. Premièrement, les conséquences d'une mosaïque somatique ont été illustrées grâce à l'étude d'une famille ayant bénéficié de cinq diagnostics prénatals. Dans ces familles, certains fœtus porteurs de l'allèle à risque identifié par une approche indirecte basée sur l'étude de microsatellites au locus de RB1, n'étaient pas porteurs de la mutation du parent atteint, lui-même atteint d'un rétinoblastome bilatéral. Ainsi, nous avons démontré la présence d'une mosaïque somatique et gonadique chez ce parent lourdement atteint. La conséquence de l'existence de patients présentant une mosaïque dans le cadre du conseil génétique a été discutée. La suite de nos travaux a pris en compte ces résultats afin de limiter les biais que pourrait induire la présence de mutations en mosaïque dans des études de corrélation génotype/phénotype dans le rétinoblastome. Deuxièmement, l'association de grandes délétions emportant RB1 avec des retards psychomoteurs chez des patients atteints de rétinoblastome a été étudiée. Une approche de CGH hautement résolutive, ciblée sur le locus de RB1, a été mise en place afin de caractériser le rôle des gènes contigus de RB1 dans ce syndrome. Ainsi, cette approche a permis de définir une zone à risque de retard psychomoteur que nous proposons comme seuil d'alerte pour le généticien. Cette zone définit un gène, PCDH8 d'expression cérébrale exclusive, comme un excellent candidat au retard psychomoteur. Enfin, troisièmement, une approche " gène candidat " reposant sur l'étude du SNP309 du promoteur de MDM2, a été mise en œuvre.
105

Molekulární diferenciace pohlavních chromosomů předivek rodu \kur{Yponomeuta} / Molecular differentiation of sex chromosomes in ermine moths of genus \kur{ Yponomeuta}

VESELÁ, Jana January 2012 (has links)
Structure of the karyotype of three species in ermine moths (Yponomeuta: Yponomeutidae, Lepidoptera) was investigated by means of several cytogenetic methods (DAPI staining, orcein staining, CGH and GISH with telomeric probe) focusing on their sex chromosomes. Additionally, the origin of the Z2 chromosome in the WZ1Z2/Z1Z1Z2Z2 sex chromosome system (specific for this family of butterflies) was tested using southern hybridization.
106

Estudo genético-clínico e molecular da síndrome de Rokitansky-Mayer-Küster-Hauser e condições afins / Clinical, genetic and molecular study of Rokitansky-Mayer-Küster-Hauser syndrome and related conditions

Carola Cheroki 28 April 2008 (has links)
Introdução: A síndrome ou seqüência malformativa de Rokitansky-Mayer-Küster-Hauser (SR), de caráter geralmente esporádico, caracteriza-se por aplasia útero-vaginal, freqüentemente associada a anomalias esqueléticas e do trato urinário e a caracteres sexuais secundários, hormônios esteróides e cariótipo normais. A condição é claramente heterogênea, podendo fazer parte de outras seqüências e complexos mais abrangentes. Sua freqüência ao nascimento foi estimada em cerca de 1/5.000 meninas. O banco de dados OMIM (McKusick, 2005) classifica-a como autossômica recessiva e apenas um caso atípico, portador de virilização, foi atribuído a mutação descrita no gene WNT4 (Biason-Laubert e col.., 2004). A vitamina A e seus derivados ativos (ácidos retinóicos ou AR) desempenham papel importante nos processos de diferenciação, proliferação e apoptose celular. Mendelsohn e col. (1994) e Kastner e col. (1997) descreveram malformações congênitas semelhantes afins às da SR em camundongos portadores de mutações nos genes RAR-G e RXR-A dos receptores de AR. A região homóloga em humanos de um desses receptores corresponde exatamente à região descrita por Kucheria e col. (1988) em duas mulheres não aparentadas com agenesia mülleriana e portadoras de translocação (12;14)(q14;q31). Os fatores etiológicos responsáveis pelas anomalias müllerianas são ainda pouco conhecidos, mas o achado freqüente de afetadas com outros defeitos associados (renais, esqueléticos, cardíacos e auditivos) sugere o envolvimento de genes primordiais do desenvolvimento. Materiais e métodos: No total, 43 pacientes (todas com cariótipo 46,XX) e 21 familiares foram todos submetidos a exame clínico e ginecológico e de imagem (ultra-sonografia urogenital e raios-X de coluna) padronizados e à coleta de sangue para estudo cromossômico e molecular. O DNA foi extraído e amplificado por PCR Touch-Down; a triagem das mutações foi realizada em cinco genes (RARG, RXR-A, WNT-4, LHX-1 e KLHL-4) por eletroforese SSCP, dHPLC e de seqüenciamento (MegaBace). Quinze pacientes do total apresentando fenótipo mais grave foram triadas quanto a variações no número de cópias de DNA pela técnica de ~1 Mb array-CGH. As alterações detectadas foram validadas por FISH e MLPA. Foram excluídas alterações no número de cópias previamente descritas em indivíduos normais (DGV). Dois novos genes (LHX-1 e KLHL-4) surgiram como possíveis candidatos após a triagem com array- CGH e foram incluídos aos três genes candidatos previamente existentes. Resultados e conclusão: Trinta e nove pacientes possuíam quadro bastante típico de SR com agenesia útero-vaginal, em 27 delas acompanhado de manifestações extra-genitais como defeitos renais, ósseos, agenesia de ovários e surdez. Quatro pacientes apresentaram defeitos müllerianos isolados (agenesia de vagina) e uma outra era portadora da associação MURCS. A analise molecular por meio das técnicas de SSCP, dHPLC e seqüenciamentode todas as regiões codificados dos cinco genes candidatos permitiu identificar 95 alterações. A comparação com os bancos de dados (http://www.ensembl.org/) determinou que as alterações identificadas correspondem a variações populacionais polimórficas previamente descritas e sem efeito patogênico, uma vez que nenhuma delas altera a seqüência de aminoácidos das proteínas por elas codificadas. Mediante array-CGH foram identificadas, em 5 pacientes, um total de 7 alterações submicroscópicas (deleções e duplicações) comprometendo as regiões 1q21.1, 17q12, 22q11.21, 22q11.22, e Xq21.31. Alguns familiares das afetadas, também portadores dessas alterações, apresentavam manifestações leves, indicando que as alterações apresentam penetrância incompleta e expressividade variável. Nossos resultados afastam a RAR-G, RXR-A, WNT-4 como diretamente envolvidos na patogênese da síndrome de Rokitansky e sugerem a existência de variações no numero de copias de novas regiões cromossômicas como relevantes durante o desenvolvimento mülleriano, indicando especificamente os genes LHX1 e KLHL4 como candidatos. / Background: Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, comprising utero-vaginal atresia in otherwise phenotypically normal women with a normal karyotype (46,XX), has an incidence of about 1/5,000 among newborn girls. Anomalies of the genital tract range from upper vaginal atresia to total Müllerian agenesis (congenital absence of the Fallopian tubes, uterus, and upper vagina). Patients with müllerian aplasia (MA) often exhibit additional clinical features such as renal, vertebral and cardiac defects. A number of different syndromes have been associated with MA, and in most cases its aetiology remains poorly understood. We studied 43 women with the MRKH defect and 21 relatives presenting associated anomalies. The study included clinical and ultrasonographic examination of the urogenital system, radiographs of the vertebral column and sequencing of three candidate genes named RAR gama, RXR alpha and WNT-4. Fifteen of our patients, with more complex phenotypes (genital, renal, cardiac, and skeletal defects), were screened for DNA copy number changes by 1 Mb whole genome bacterial artificial chromosome (BAC) array based comparative genomic hybridization (CGH). The detected alterations were validated by an independent method and further mapped by high resolution oligo-arrays. Results: All patients had a normal 46,XX karyotype and were also normal to the RAR gama, RXR alpha and WNT-4 genes. Submicroscopic genomic imbalances affecting the 1q21.1, 17q12, 22q11.21, and Xq21.31 chromosome regions were detected in five probands. Presence of the alterations in the normal mother of one patient suggests incomplete penetrance and/or variable expressivity. Conclusion: 5 of the 15 patients were found to have cryptic genomic alterations. The imbalances on 22q11.21 support recent findings by us and others that alterations in this chromosome region may result in impairment of müllerian duct development. The remaining imbalances indicate involvement of previously unknown chromosome regions in MA, and point specifically to LHX1 and KLHL4 as candidate genes.
107

Záchyt submikroskopických aberací u fenotypově abnormálních nosičů zjevně balancovaných chromozomových přestaveb metodou array CGH / Detection of submicroscopic chromosomal aberrations in phenotypically abnormal carriers of apparently balanced rearrangements using array CGH

Slámová, Zuzana January 2020 (has links)
Carriers of apparently balanced chromosomal aberrations (BCA) are usually phenotypically normal. However, it has been estimated that up to 27% of these BCA may be associated with an abnormal phenotype, most often caused by cryptic imbalances at the breakpoints, gene disruption by the breakpoint or via the position effect. In contrast to conventional karyotyping, molecular cytogenetic techniques enable more detailed BCA characterization and better correlation between genotype and phenotype of the patient. The aim of this thesis was to evaluate the presence of copy number variants (CNVs) at breakpoints or elsewhere in the genome in patients with abnormal phenotype who carry de novo or inherited BCA. 54 BCA were investigated using array CGH (20 de novo cases, 27 inherited and 7 cases of unknown origin) including 32 reciprocal translocations, 6 robertsonian translocations, 12 inversions and 4 complex chromosomal rearrangements. If possible, the parents were also examined to ascertain the inheritance of the relevant CNVs. In order to specify microarray findings or exclude gene disruption, FISH was used in selected patients. Among the patients included, in 31,5% (17/54) at least one (in 8 patients more than one) significant CNV was detected. Four cases carried cryptic imbalances only at the breakpoints,...
108

Évaluation du caryotype moléculaire en tant qu’outil diagnostique chez les enfants avec déficience intellectuelle et/ou malformations congénitales

D'Amours, Guylaine 05 1900 (has links)
Le caryotype moléculaire permet d’identifier un CNV chez 10-14% des individus atteints de déficience intellectuelle et/ou de malformations congénitales. C’est pourquoi il s’agit maintenant de l’analyse de première intention chez ces patients. Toutefois, le rendement diagnostique n’est pas aussi bien défini en contexte prénatal et l’identification de CNVs de signification clinique incertaine y est particulièrement problématique à cause du risque d’interruption de grossesse. Nous avons donc testé 49 fœtus avec malformations majeures et un caryotype conventionnel normal avec une micropuce CGH pangénomique, et obtenu un diagnostic dans 8,2% des cas. Par ailleurs, des micropuces à très haute résolution combinant le caryotype moléculaire et le génotypage de SNPs ont récemment été introduites sur le marché. En plus d’identifier les CNVs, ces plateformes détectent les LOHs, qui peuvent indiquer la présence d’une mutation homozygote ou de disomie uniparentale. Ces anomalies pouvant être associées à la déficience intellectuelle ou à des malformations, leur détection est particulièrement intéressante pour les patients dont le phénotype reste inexpliqué. Cependant, le rendement diagnostique de ces plateformes n’est pas confirmé, et l’utilité clinique réelle des LOHs n’est toujours pas établie. Nous avons donc testé 21 enfants atteints de déficience intellectuelle pour qui les méthodes standards d’analyse génétique n’avaient pas résulté en un diagnostic, et avons pu faire passer le rendement diagnostique de 14,3% à 28,6% grâce à l’information fournie par les LOHs. Cette étude démontre l’utilité clinique d’une micropuce CGH pangénomique chez des fœtus avec malformations, de même que celle d’une micropuce SNP chez des enfants avec déficience intellectuelle. / Molecular karyotyping identifies a CNV in 10-14% of individuals affected with intellectual disability and/or congenital abnormalities. Therefore, it is now the first-tier analysis for these patients. However, the diagnostic yield is not as clear in the prenatal context, and the risk of pregnancy termination makes the detection of variants of uncertain clinical significance particularly problematic. We tested 49 fetuses with major malformations and a normal karyotype, using a pangenomic CGH array, and obtained a diagnosis in 8.2% of cases. Furthermore, high-resolution microarrays combining molecular karyotyping and SNP genotyping were recently introduced on the market. In addition to identifying CNVs, these platforms detect LOHs, which can indicate the presence of a homozygous mutation or of uniparental disomy. Since these abnormalities can be associated with intellectual disability or congenital abnormalities, their detection is of particular interest for patients whose phenotype remains unexplained. However, the diagnostic yield obtained with these platforms is not confirmed, and the real clinical value of LOH detection is not yet established. We tested 21 children affected with intellectual disability for whom standard genetic analyses failed to provide a diagnosis, and were able to increase the diagnostic yield from 14.3% to 28.6% as a result of the information provided by LOHs. This study shows the clinical usefulness of pangenomic CGH arrays in fetuses with malformation(s), as well as that of SNP arrays in children with intellectual disability.
109

Implication des remaniements géniques dans l'inactivation des gènes de prédisposition au cancer du sein / Germline large rearrangements in the inactivation of genes implied in breast cancer predisposition

Rouleau, Etienne 07 December 2011 (has links)
Parmi les cancers du sein, 5 à 10% serait associé à une prédisposition génétique familiale. La prise en charge des patients prédisposés nécessite une bonne définition des risques de cancer. L’identification de l’altération moléculaire causale dans chacune de ces familles est donc un enjeu essentiel dans la prise en charge médicale. Deux gènes, BRCA1 et BRCA2, sont associés à une prédisposition majeure au cancer du sein et de l’ovaire depuis le milieu des années 1990, expliquant environ 15% des formes héréditaires. L’analyse moléculaire de ces deux gènes est désormais réalisée en routine pour la recherche de variations nucléotidiques et plus récemment de remaniements géniques ce qui a permis d’améliorer le taux de détection de mutations délétères. Cependant, pour près de 85% des familles avec une agrégation familiale ou un âge anormalement jeune de cancer du sein, aucune mutation délétère n’a pu être mise en évidence. Dans ce contexte, mon travail de thèse a eu pour objectif de tester plusieurs hypothèses permettant d’expliquer les risques de cancer du sein observés chez des familles montrant l’absence de mutation des gènes BRCA1 et BRCA2. Nous avons ainsi recherché des mécanismes d’altération rarement explorés pour les gènes BRCA1 et BRCA2, et enfin analysé d’autres gènes candidats dont le gène CDH1 et huit autres gènes impliqués dans la réparation de l’ADN. Nous avons pu mieux caractériser des remaniements sur les gènes BRCA1 et BRCA2. Enfin, nous avons pu évaluer l’impact de variants de signification inconnue et des réarrangements détectés par l’étude de leurs transcrits. Dans un premier temps, nous avons mis en place et validé de nouvelles approches techniques de détection et de caractérisation : la CGH-array dédiée, la qPCR-HRM et le peignage moléculaire. Ces techniques ont ensuite été utilisées pour étudier les remaniements géniques et leur fréquence pour onze gènes candidats à la prédisposition au cancer du sein à partir de 472 familles négatives aux mutations délétères BRCA1 et BRCA2. Parmi ces 11 gènes, nous pouvons conclure que les remaniements géniques détectés concernent principalement les gènes BRCA1 et BRCA2, et à un moindre degré le gène CHEK2. En appliquant ces techniques, nous avons pu décrire de nouveaux événements, deux larges délétions et une duplication intronique, pour les gènes CDH1 et BARD1, ouvrant de nouvelles perspectives sur l’étude des transcrits alternatifs. Nous avons en particulier pu décrire la grande diversité des réarrangements délétères en 5’ du gène BRCA1. L’enjeu est ensuite l’interprétation de ces événements. Notre étude des transcrits a permis de décrire un variant exonique d’épissage entraînant une délétion de l’exon 23 au niveau du transcrit BRCA1. Nous avons aussi validé la pathogénicité d’un réarrangement en phase de l’exon 3 de BRCA2 par une étude quantitative du transcrit et une évaluation de la coségrégation. Au final, moins de 1% de nouveaux remaniements ont été mis en évidence. Ce travail est riche d’enseignement pour les nouvelles investigations à mettre en place pour les familles prédisposées. En dehors de la technique d’identification, il est nécessaire de développer des stratégies de validation basées principalement sur la quantification des effets de ces altérations au niveau de l’ARN et des protéines. Cependant, il manque encore de nombreux chaînons pour expliquer l’héritabilité des cancers du sein. Les études sur les nouveaux gènes candidats et l’avènement des techniques de séquençage pangénome à haut débit, devraient permettre d’avoir une meilleure vision des phénomènes pathobiologiques liés à la prédisposition au cancer du sein. / Five to 10% of breast cancers are linked to a genetic predisposition. The management of patients at risk requires a good definition in the risk of cancer. The identification of causal molecular alterations in each of these families is a key issue in medical care. Two genes, BRCA1 and BRCA2, are related with the greatest susceptibility to breast cancer and ovarian cancer since the mid-1990s, accounting for about 15% of hereditary forms. Molecular analysis of these two genes is now routinely performed for the detection of nucleotide variations and more recently large rearrangements which have improved the detection rate of deleterious mutations. However, for more than 85% of families, no mutation explains familial aggregation or unusual young age of breast cancer onset. In this context, my thesis aimed at testing several hypotheses to explain the risks of breast cancer observed in families without any identified mutations in the BRCA1 and BRCA2 genes. We investigated some mechanisms of genic rearrangements rarely explored for BRCA1 and BRCA2 genes, and finally investigated other candidate genes, especially CDH1 gene and eight other genes involved in double-strand DNA repair. We have better characterized some rearrangements in the BRCA1 and BRCA2 genes. Finally, we applied RNA quantitative approaches to better assess the impact from variants of unknown significance and detected rearrangements. Initially, we developed and validated new technical approaches for detection and characterization such as dedicated CGH-array, qPCR-HRM and molecular combing. Rare large germline rearrangements and their frequency in eleven candidate genes for susceptibility to breast cancer were studied among 472 families negative by routine testing for BRCA1 and BRCA2 genes. Of these 11 genes, we conclude that genic rearrangements are found then mainly in the BRCA1 and BRCA2 genes, and to a lesser extent in the CHEK2 gene. We were able to describe two large intronic deletions and one duplication for the CDH1 and BARD1 genes, opening new perspectives on the regulation of their alternative transcript. In particular, we described the wide diversity of new rearrangements involving the 5' region of the BRCA1 gene. Then, it is necessary to validate and interpret those new events. Our transcript analysis described a new exonic variant causing the splice deletion of exon 23 in BRCA1 gene. We have developed tools to validate an in-frame large rearrangement of BRCA2 exon 3 with some transcript quantitative approaches and disease cosegregation.Finally, less than 1% of new rearrangements have been identified. This work is instructive for further investigations to establish molecular etiology in those families with breast cancer predisposition. Not only by applying new technologies, it is necessary to develop other strategies based primarily on quantifying effects of these alterations on transcription and traduction. However, it still lacks many links to explain the heritability of breast cancer. The combination of new candidate genes studies and the advent of high-throughput sequencing are expected to give a better vision of pathobiological phenomena related to the breast cancer predisposition.
110

Zytogenetische Grundlage der malignen Progression anaplastischer Astrozytome: Chromosomale Aberrationen von Primärtumoren, Rezidiven und ihr Einfluss auf das Überleben / Cytogenetic basics of malignant progression of anaplastic astrocytoma: Chromosomal aberrations of primary and recurrent tumors and their influence on survival

Haupt, Jörn 02 November 2011 (has links)
No description available.

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