Introdução: Durante as últimas décadas, a utilização de métodos moleculares como Hibridizacão in situ por fluorescência (FISH) e Hibridização Genômica Comparativa (array-CGH) mudou dramaticamente a perspectiva em relação à detecção de rearranjos genômicos submicroscópicos. O número de doenças identificadas como causada por microdeleções/microduplicações cromossômicas aumentou rapidamente, trazendo um papel crucial para a citogenética no diagnóstico destas condições. Objetivo: O objetivo deste estudo foi identificar e caracterizar microdeleções cromossômicas associadas a síndromes de malformações em um laboratório de citogenética de referência de um hospital público do sul do Brasil. Métodos: Estudo retrospectivo e prospectivo, em uma série consecutiva de amostras. O estudo foi baseado em registros hospitalares e laboratoriais de amostras de uma coorte de pacientes com suspeita clínica de microdeleção cromossômica. Foram selecionadas amostras de indivíduos em que o diagnóstico clínico proposto incluia uma suspeita de rearranjo nos cromossomos 4p16.3, 5p15.2, 5q35, 7q11.23, 8q24.12, 15q11-q12, 16p13.3, 17p13.3, 17p11. 2,2 e 22q11 que foram analisados por hibridização in situ por fluorescência (FISH). Em 11 amostras com microdeleções, hibridização genômica comparativa (array-CGH) foi realizada. Resultados: Um total de 504 amostras foram avaliadas, sendo as suspeitas mais comuns a deleção 22q11.2 (29,5%), a síndrome de Prader-Willi (21,6%), a síndrome de Williams-Beuren (15%) e da síndrome de Angelman (13 %). Em 120 deles (23,8%) desequilíbrios cromossómicas relacionadas com o diagnóstico clínico foram encontrados. A del7q11.23 foi a alteração mais frequente (8,5%) detectada, seguida por del22q11.2 (5,3%) e del15q11-q12 (4,5%). Conclusões: Nossos achados reforçam à estratégia de que um teste de citogenética molecular sensível associada com uma avaliação clínico qualificado são cruciais para a detecção e caracterização precisa de deleções cromossômicas submicroscópicas. Além disso, nosso estudo enfatiza a necessidade de educação continuada para o desenvolvimento e utilização de novas tecnologias para o diagnóstico citogenético, as quais, em nossa experiência, puderam ser introduzidas com sucesso em um hospital público do sul do Brasil. / Background: During the past decades, the widespread use of FISH and microarray-based technologies dramatically changed our perspective regarding detection of submicroscopic genomic rearrangements. The number of diseases identified as caused by chromosomal microdeletions/microduplications increased quickly, bringing a new and crucial role for cytogenetics in the diagnosis of these conditions. Objective: The purpose of this study was to identify and chraracterize chromosomal microdeletions associated with malformation syndromes in a reference cytogenetics laboratory from a public hospital of Southern Brazil. Methods: Using retrospective and prospective approaches, we evaluated a consecutive series of samples. The study was based in hospital and laboratorial records of samples from a cohort of subjects with clinical suspicion of a chromosomal microdeletion. We selected samples from subjects in whom a clinical diagnosis was proposed, which included deletion of chromosomes 4p16.3, 5p15.2, 5q35, 7q11.23, 8q24.12, 15q11-q12, 16p13.3, 17p13.3, 17p11.2,2 and 22q11 identified by fluorescence in situ hybridization (FISH) analysis. In 11 samples with microdeletions, array-based comparative genomic hybridization (array-CGH) was performed. Results: A total of 504 samples were evaluated, being the most common suspicions the 22q11.2 deletion (29.5%), the Prader-Willi syndrome (21.6%), the Williams-Beuren syndrome (15%) and the Angelman syndrome (13%). In 120 of them (23.8%) chromosomal imbalances related to the clinical diagnosis were found. The deletion 7q11.23 was the most frequently finding (8.5%), followed by del22q11.2 (5.3%) and del15q11-q12 (4.5%). Conclusions: Our findings provide support to the idea that a sensitive molecular cytogenetic test associated with a qualified clinical evaluation are crucial for the detection and precise characterization of submiscroscopic chromosome deletions. Additionally, our study emphasizes the need of continuing 6 education for the improvement of the cytogenetic diagnosis technology, which was successfully introduced in a public hospital of Southern Brazil.

The human genome is a dynamic structure, recently recognized to present with significant large-scale structural variation. DNA-copy number changes represent one common type of such variation and is found both between individuals and within the somatic cells of the same individual, especially in disease states like cancer.  Apart from DNA-rearrangements, epigenomic changes are increasingly acknowledged as important events in the maintenance of genomic integrity. In this thesis, different array-based methods have been applied for global genomic and epigenomic profiling of both normal and cancer cells. In paper I, a genomic microarray was established and used to determine DNA-copy number variants (CNVs) in a cohort of 76 healthy individuals from three ethnic populations. We identified 315 CNV regions that in total encompassed ~3,5% of the genome. In paper II, the array was utilized to discover CNVs within several differentiated tissues from the same subject. Six variants were identified providing evidence for somatic mosaicism. In paper III and IV we studied pheochromocytomas and paragangliomas, rare endocrine tumours that most often present as benign and sporadic with unclear genetic/epigenetic cause. Genome-wide DNA-copy number analysis of 53 benign and malignant samples in paper III revealed numerous common and novel chromosomal regions of losses and gains. High frequencies of relatively small overlapping regions of deletions were detected on chromosome 1p arm, encompassing several candidate tumour suppressor genes. In paper IV, an epigenomic map for two histone modifications associated with silent (H3K27me3) or active (H3K4me3) gene transcription, was generated for one malignant pheochromocytoma. Integrated analysis of global histone methylation, copy number alterations and gene expression data aided in the identification of candidate tumour genes. In conclusion, the performed studies have contributed to gain knowledge of CNVs in healthy individuals, and identified regions and genes which are likely associated with the development and progression of pheochromocytoma/paraganglioma.

Gene activity is regulated at two separate layers. Through structural and chemical properties of DNA – the primary layer of encoding – local signatures may enable, or disable, the binding of proteins or complexes of them with regulatory potential to the DNA. At a higher level – the structural layer of encoding – gene activity is regulated through the properties of higher order DNA structure, chromatin, and chromosome organization. Cells with abnormal chromosome compaction or organization, e.g. cancer cells, may thus have perturbed regulatory activities resulting in abnormal gene activity. Hence, there is a great need to decode the transcriptional regulation encoded in both layers to further our understanding of the factors that control activity and life of a cell and, ultimately, an organism. Modern genome-wide studies with those aims rely on data-intense experiments requiring sophisticated computational and statistical methods for data handling and analyses. This thesis describes recent advances of analyzing experimental data from quantitative biological studies to decipher the structural layer of encoding in human cells. Adopting an integrative approach when possible, combining multiple sources of data, allowed us to study the influences of chromatin (Papers I and II) and chromosomal aberrations (Paper IV) on transcription. Combining chromatin data with chromosomal aberration data allowed us to identify putative driver oncogenes and tumor-suppressor genes in cancer (Paper IV). Bayesian approaches enabling the incorporation of background information in the models and the adaptability of such models to data have been very useful. Their usages yielded accurate and narrow detection of chromosomal breakpoints in cancer (Papers III and IV) and reliable positioning of nucleosomes and their dynamics during transcriptional regulation at functionally relevant regulatory elements (Paper II). Using massively parallel sequencing data, we explored the chromatin landscapes of human cells (Papers I and II) and concluded that there is a preferential and evolutionary conserved positioning at internal exons nearly unaffected by the transcriptional level. We also observed a strong association between certain histone modifications and the inclusion or exclusion of an exon in the mature gene transcript, suggesting a functional role in splicing.

La déficience intellectuelle (DI) touche 1 à 3% de la population générale avec un excès de sujets de sexe masculin. Cette affection est caractérisée par une extrême hétérogénéité clinique et génétique rendant son élucidation complexe. La révolution technologique des outils permettant l’analyse du génome intervenue depuis les années 2000 avec l’analyse chromosomique sur microréseau et singulièrement depuis 2010 avec les applications du séquençage à haut débit a considérablement facilité l’identification de nouveaux gènes. Nous avons tiré avantage de ce phénomène pour identifier trois affections neurologiques à caractère familial Nous avons procédé selon une méthodologie structurée pour conduire, grâce à la mise en place d’un réseau de collaborations, à la découverte ou à la confirmation de l’existence de nouvelles formes de DI. 1.Séquençage de l'exome couplé à la recherche de variations du nombre de copies 2. Mise à jour d’une altération de séquence génique potentiellement causale retrouvée chez le cas index et chez les autres sujets atteints de la famille 3.Extension des résultats à d’autres familles par la constitution d’une cohorte de réplication 4.Élaboration d’une série d’études fonctionnelles venant conforter l’hypothèse de causalité par la création d’un modèle animal et/ou la réalisation d’études biochimiques spécifiquesL’application de cette méthodologie nous a permis de conduire à terme trois projets : L’individualisation d’une forme syndromique de DI récessive autosomique associée à une malformation du rachis cervical et liée aux mutations bi-alléliques de CDK10. La caractérisation d’une encéphalopathie récessive autosomique létale associée à une hypertonie sévère et à une arthrogrypose distale liée aux mutations bi-alléliques d’ATAD1. L’implication de FRMPD4 dans une nouvelle forme de DI non syndromique liée à l’X / Intellectual disability (ID) impacts 1 to 3% of the general population with an excess of affected males. This condition is characterized by an extreme clinical and genetic heterogeneity making the deciphering of its causes more complex. The technological revolution that took place in the study of the genome over the last two decades has provided a useful tool for identification of new genetic entities. This is particularly true for chromosomal micro-array analysis since early 2000s and for next generation sequencing since 2011. We took advantage of this by identifying the molecular basis of three singular conditions. We applied a structured methodology and created a network of collaborations to define or confirm these new ID syndromes. 1. Whole exome sequencing alongside with array-CGH 2.Identification of a candidate gene sequence alteration in the index case and other affected patients of the family 3.Constitution and study of a replication cohort 4.Biochemical studies and/or animal models in order to support the assumption of causalityBased on this research strategy, we were able to complete the following projects : Discovery of a syndromic form of autosomal recessive ID associated with cervical spine defects due to bi-allelic CDK10 mutations. Identification of an ATAD1-related profound and lethal autosomal recessive encephalopathy with stiffness and distal arthrogryposis. Characterization of a FRMPD4-related X-linked non-syndromic ID

Introdução: Durante as últimas décadas, a utilização de métodos moleculares como Hibridizacão in situ por fluorescência (FISH) e Hibridização Genômica Comparativa (array-CGH) mudou dramaticamente a perspectiva em relação à detecção de rearranjos genômicos submicroscópicos. O número de doenças identificadas como causada por microdeleções/microduplicações cromossômicas aumentou rapidamente, trazendo um papel crucial para a citogenética no diagnóstico destas condições. Objetivo: O objetivo deste estudo foi identificar e caracterizar microdeleções cromossômicas associadas a síndromes de malformações em um laboratório de citogenética de referência de um hospital público do sul do Brasil. Métodos: Estudo retrospectivo e prospectivo, em uma série consecutiva de amostras. O estudo foi baseado em registros hospitalares e laboratoriais de amostras de uma coorte de pacientes com suspeita clínica de microdeleção cromossômica. Foram selecionadas amostras de indivíduos em que o diagnóstico clínico proposto incluia uma suspeita de rearranjo nos cromossomos 4p16.3, 5p15.2, 5q35, 7q11.23, 8q24.12, 15q11-q12, 16p13.3, 17p13.3, 17p11. 2,2 e 22q11 que foram analisados por hibridização in situ por fluorescência (FISH). Em 11 amostras com microdeleções, hibridização genômica comparativa (array-CGH) foi realizada. Resultados: Um total de 504 amostras foram avaliadas, sendo as suspeitas mais comuns a deleção 22q11.2 (29,5%), a síndrome de Prader-Willi (21,6%), a síndrome de Williams-Beuren (15%) e da síndrome de Angelman (13 %). Em 120 deles (23,8%) desequilíbrios cromossómicas relacionadas com o diagnóstico clínico foram encontrados. A del7q11.23 foi a alteração mais frequente (8,5%) detectada, seguida por del22q11.2 (5,3%) e del15q11-q12 (4,5%). Conclusões: Nossos achados reforçam à estratégia de que um teste de citogenética molecular sensível associada com uma avaliação clínico qualificado são cruciais para a detecção e caracterização precisa de deleções cromossômicas submicroscópicas. Além disso, nosso estudo enfatiza a necessidade de educação continuada para o desenvolvimento e utilização de novas tecnologias para o diagnóstico citogenético, as quais, em nossa experiência, puderam ser introduzidas com sucesso em um hospital público do sul do Brasil. / Background: During the past decades, the widespread use of FISH and microarray-based technologies dramatically changed our perspective regarding detection of submicroscopic genomic rearrangements. The number of diseases identified as caused by chromosomal microdeletions/microduplications increased quickly, bringing a new and crucial role for cytogenetics in the diagnosis of these conditions. Objective: The purpose of this study was to identify and chraracterize chromosomal microdeletions associated with malformation syndromes in a reference cytogenetics laboratory from a public hospital of Southern Brazil. Methods: Using retrospective and prospective approaches, we evaluated a consecutive series of samples. The study was based in hospital and laboratorial records of samples from a cohort of subjects with clinical suspicion of a chromosomal microdeletion. We selected samples from subjects in whom a clinical diagnosis was proposed, which included deletion of chromosomes 4p16.3, 5p15.2, 5q35, 7q11.23, 8q24.12, 15q11-q12, 16p13.3, 17p13.3, 17p11.2,2 and 22q11 identified by fluorescence in situ hybridization (FISH) analysis. In 11 samples with microdeletions, array-based comparative genomic hybridization (array-CGH) was performed. Results: A total of 504 samples were evaluated, being the most common suspicions the 22q11.2 deletion (29.5%), the Prader-Willi syndrome (21.6%), the Williams-Beuren syndrome (15%) and the Angelman syndrome (13%). In 120 of them (23.8%) chromosomal imbalances related to the clinical diagnosis were found. The deletion 7q11.23 was the most frequently finding (8.5%), followed by del22q11.2 (5.3%) and del15q11-q12 (4.5%). Conclusions: Our findings provide support to the idea that a sensitive molecular cytogenetic test associated with a qualified clinical evaluation are crucial for the detection and precise characterization of submiscroscopic chromosome deletions. Additionally, our study emphasizes the need of continuing 6 education for the improvement of the cytogenetic diagnosis technology, which was successfully introduced in a public hospital of Southern Brazil.

Introdução: Durante as últimas décadas, a utilização de métodos moleculares como Hibridizacão in situ por fluorescência (FISH) e Hibridização Genômica Comparativa (array-CGH) mudou dramaticamente a perspectiva em relação à detecção de rearranjos genômicos submicroscópicos. O número de doenças identificadas como causada por microdeleções/microduplicações cromossômicas aumentou rapidamente, trazendo um papel crucial para a citogenética no diagnóstico destas condições. Objetivo: O objetivo deste estudo foi identificar e caracterizar microdeleções cromossômicas associadas a síndromes de malformações em um laboratório de citogenética de referência de um hospital público do sul do Brasil. Métodos: Estudo retrospectivo e prospectivo, em uma série consecutiva de amostras. O estudo foi baseado em registros hospitalares e laboratoriais de amostras de uma coorte de pacientes com suspeita clínica de microdeleção cromossômica. Foram selecionadas amostras de indivíduos em que o diagnóstico clínico proposto incluia uma suspeita de rearranjo nos cromossomos 4p16.3, 5p15.2, 5q35, 7q11.23, 8q24.12, 15q11-q12, 16p13.3, 17p13.3, 17p11. 2,2 e 22q11 que foram analisados por hibridização in situ por fluorescência (FISH). Em 11 amostras com microdeleções, hibridização genômica comparativa (array-CGH) foi realizada. Resultados: Um total de 504 amostras foram avaliadas, sendo as suspeitas mais comuns a deleção 22q11.2 (29,5%), a síndrome de Prader-Willi (21,6%), a síndrome de Williams-Beuren (15%) e da síndrome de Angelman (13 %). Em 120 deles (23,8%) desequilíbrios cromossómicas relacionadas com o diagnóstico clínico foram encontrados. A del7q11.23 foi a alteração mais frequente (8,5%) detectada, seguida por del22q11.2 (5,3%) e del15q11-q12 (4,5%). Conclusões: Nossos achados reforçam à estratégia de que um teste de citogenética molecular sensível associada com uma avaliação clínico qualificado são cruciais para a detecção e caracterização precisa de deleções cromossômicas submicroscópicas. Além disso, nosso estudo enfatiza a necessidade de educação continuada para o desenvolvimento e utilização de novas tecnologias para o diagnóstico citogenético, as quais, em nossa experiência, puderam ser introduzidas com sucesso em um hospital público do sul do Brasil. / Background: During the past decades, the widespread use of FISH and microarray-based technologies dramatically changed our perspective regarding detection of submicroscopic genomic rearrangements. The number of diseases identified as caused by chromosomal microdeletions/microduplications increased quickly, bringing a new and crucial role for cytogenetics in the diagnosis of these conditions. Objective: The purpose of this study was to identify and chraracterize chromosomal microdeletions associated with malformation syndromes in a reference cytogenetics laboratory from a public hospital of Southern Brazil. Methods: Using retrospective and prospective approaches, we evaluated a consecutive series of samples. The study was based in hospital and laboratorial records of samples from a cohort of subjects with clinical suspicion of a chromosomal microdeletion. We selected samples from subjects in whom a clinical diagnosis was proposed, which included deletion of chromosomes 4p16.3, 5p15.2, 5q35, 7q11.23, 8q24.12, 15q11-q12, 16p13.3, 17p13.3, 17p11.2,2 and 22q11 identified by fluorescence in situ hybridization (FISH) analysis. In 11 samples with microdeletions, array-based comparative genomic hybridization (array-CGH) was performed. Results: A total of 504 samples were evaluated, being the most common suspicions the 22q11.2 deletion (29.5%), the Prader-Willi syndrome (21.6%), the Williams-Beuren syndrome (15%) and the Angelman syndrome (13%). In 120 of them (23.8%) chromosomal imbalances related to the clinical diagnosis were found. The deletion 7q11.23 was the most frequently finding (8.5%), followed by del22q11.2 (5.3%) and del15q11-q12 (4.5%). Conclusions: Our findings provide support to the idea that a sensitive molecular cytogenetic test associated with a qualified clinical evaluation are crucial for the detection and precise characterization of submiscroscopic chromosome deletions. Additionally, our study emphasizes the need of continuing 6 education for the improvement of the cytogenetic diagnosis technology, which was successfully introduced in a public hospital of Southern Brazil.

Ce travail de thèse a permis, dans un premier temps, de mettre en évidence de nouveaux grandsréarrangements dans trois pathologies étudiées au laboratoire : la mucoviscidose, la pancréatitechronique et l’hémochromatose. En particulier, ces travaux ont permis de trouver de nouveaux CNVs(Copy Number Variations) pathologiques dans le gène CFTR (Cystic Fibrosis Transmembraneconductance Regulator), de mieux comprendre les mécanismes d’un remaniement complexe dansPRSS1 (Protease Serine 1) et d’aider à caractériser finement un réarrangement dans HFE(Hemochromatosis). Ces études ont donc servi de preuve de concept pour l’utilisation de puces à ADN àl’échelle d’un gène et dans des zones difficiles car riches en séquences répétées.Dans un second temps, la recherche de facteurs de susceptibilité génétiques aux infarctus cérébraux(AICs) du sujet jeune a été réalisée chez 168 cas et 200 témoins âgés de moins de 40 ans. Dans notrepopulation, l’hypertension, les migraines, le tabac, et la prise de stupéfiants sont des facteurs de risqueimportants, multipliant respectivement par 35, 3,8, 4 et 2,8 le risque d’AIC. Notre étude pangénomiquepar CGH-array (Comparative Genomic Hybridization-array) a mis en évidence 98 régionspolymorphiques dans le génome humain. Parmi elles, la délétion d’une partie du gène NOTCH2, pourraitjouer un rôle protecteur dans la survenue des AICs (OR=0,11 [0,01-0,87] ; p=0,013) mais qui ne dépassepas le seuil fixé par la correction de Bonferroni). Ce travail a également mis en évidence environ 400CNVs rares, dont deux récurrents chez les cas, l'un portant les gènes CRELD2 (cysteine-rich with EGFlikedomains 2) et AGL12 (asparagine-linked glycosylation 12, alpha-1, 6-mannosyltransferase) (p=0,02)et le deuxième situé en 5’ du gène VBP1 (von Hippel-Lindau binding protein 1) (p=0,04). Enfin, uneapproche gènes candidats a été effectuée sur les gènes NOTCH2 et ALOX5AP (5-lipoxygenaseactivating protein) sans donner de résultats significatifs. Ceci a également été réalisé sur les mutationsprincipales de trois gènes de la coagulation (Facteur II, Facteur V Leiden et MTHFR). Une associationsignificative a été mise en évidence entre la C677T du gène MTHFR (5,10-methyltetrahydrofolate) et lesinfarctus cérébraux du sujet jeune (OR=2,39, p=0,02 pour le génotype TT). Ce travail de thèse a permisde confirmer l’existence de facteurs de risque environnementaux et génétiques déjà connus mais surtoutd’émettre de nouvelles hypothèses génétiques dans la survenue des AICs du sujet jeune. / The use of locus-specific array-CGH (Comparative Genomic Hybridization) has allowed us to detect largerearrangements in three pathologies of our laboratory: cystic fibrosis, chronic pancreatitis andhemochromatosis. We successfully observed new pathological CNV (Copy Number Variations) in theCFTR (Cystic Fibrosis Transmembrane conductance Regulator) gene and characterized complex eventsin PRSS1 (Protease Serine 1) and HFE (Hemochromatosis) genes, showing that the use of thistechnique is possible even in regions with high sequence homologies.We also confirmed that hypertension, migraine, tobacco and drugs are high significant risk factors forischemic strokes (IS) in young population (under 40 years) (OR=35, 3.8, 4 and 2.8, respectively). Then,we tried to identify new genetic susceptibility loci using a pangenomic approach. Among the 98 copynumber polymorphisms (CNP) observed, an interstitial NOTCH2 deletion is candidate for a protective rolein IS (OR=0.11 [0.01-0.87] ; p=0.013 before Bonferonni correction). We also observed approximately 400uncommon CNV, two of them being particularly reccurent in patients: a 22q13.31 duplication containingCRELD2 (cysteine-rich with EGF-like domains 2) and AGL12 (asparagine-linked glycosylation 12, alpha-1, 6-mannosyltransferase) genes (p=0.02) and a Xq28 deletion localised in the 5’ region of the VBP1 (vonHippel-Lindau binding protein 1) gene (p=0.04). We also applied a candidate-gene approach onNOTCH2, ALOX5AP (5-lipoxygenase activating protein) and coagulation genes (Factor II, Factor VLeiden and MTHFR). A significant association was found for the C677T in the MTHFR gene (5,10-methyltetrahydrofolate) and young ischemic strokes (OR=2.39, p=0.02 for TT genotype). In conclusion,this study confirmed the implication of environmental and genetic factors in ischemic strokes before 40years and suggests new genetic risk factors for IS.

The thesis focuses mostly on discovering unrevealed causes of pathologic phenotype symptoms of patients with whom no pathologic changes in genetic material were detected by common cytogenetic methods. All samples were examined by a chip method array-CGH (comparative genomic hybridization) which detects aberrant spots without any knowledge of where they are located in the genome. In some cases the method was used to verify or specify the finding that was diagnosed during previous genetic testing. The patients were examined by this method in an accredited genetics laboratory GENvia, s.r.o. in 2013 and partly also in 2014. The theoretical part of the thesis focuses on the role of the common cytogenetic method and its diagnostic use. I also describe the basic principle of the array-CGH method and its use in prenatal and postnatal diagnostics. The practical part of the thesis describes results of all examined patients. But mostly it focuses on pediatric patients where the diagnosis correlates with their clinical symptoms. All the results were verified by another method used for the particular diagnosis. Some results were verified by FISH (fluorescence in situ hybridization) method, other ways of the results verification are described as well. In total 8 pathologic findings were discovered in patients up to 12...

Chromosomal aberrations are common causes of abnormal development of fetuses leading to the birth of malformed indvidual or to the intrauterine death. Half of miscarriages in the first trimester and a third in the second trimester are caused by fetal chromosomal abnormalities, mainly aneuploidies. If fetus is abnormally developed, invasive prenatal cytogenetic diagnosis should be recommended. Positive cytogenetic finding can be reason for induced abortion till the end of 24th week of gestation. We investigated 81 miscarriages, 46 fetuses from induced abortions and 80 fetuses with abnormal development from ongoing pregnancies. G-banding analysis was used as the main method for investigating miscarriages. Genomic DNA isolated from abnormally developed fetuses was screened by array CGH technique. We found 43,75 % chromosomal abnormal miscarried fetuses, majority of them with numerical aberrations (91,4 %). In group of induced abortions, 25,71 % fetuses carried chromosomal abnormality. The lowest rate 11,67 % of chromosoal aberrations was detected in group of prenatally diagnosed fetuses from ongoing pregnancies. Array CGH detected submicroscopic aberrations in 13,41 % fetuses with ultrasound findings. All together 25,74 % microscopic and causal submicroscopic chromosomal abnormalities were found to be...

Notre travail s’est intéressé à l’albinisme oculocutané en étudiant ses aspects clinico- moléculaires. Malgré l’analyse approfondie des gènes connus d’albinisme oculocutané, 15 % des patients restent sans mutation identifiée indiquant que les mutations sont situées dans des régions géniques non analysées par les techniques classiques de diagnostic moléculaire, ou qu’il existe d’autres gènes d’albinisme oculocutané. Nous avons établi une base de données clinico- biologiques décrivant les caractéristiques de plus de 400 patients analysés. Des outils de diagnostic moléculaire ont été développés à la recherche de mutations situées dans les introns et les régions régulatrices et de réarrangements géniques. Différentes stratégies ont également été utilisées pour rechercher des gènes candidats. La puce à façon a permis l’identification de grands réarrangements dans les gènes TYR, OCA2 et SLC45A2 et un réarrangement complexe du gène OCA2 chez 2 patients non apparentés. L'analyse de gènes candidats nous a permis d'identifier, chez 5 patients non apparentés présentant un albinisme oculocutané non syndromique, des mutations dans le gène SLC24A5, très récemment associé à l’AOC6. Le séquençage d’exome de 6 patients a mis en évidence des gènes candidats pour lesquels des analyses complémentaires sont poursuivies afin de confirmer leur implication dans la pathogenèse de l’AOC.Les résultats de ce travail permettent de redéfinir les aspects cliniques et moléculaires de l’AOC, d’identifier de nouveaux mécanismes moléculaires à l’origine de l’AOC ainsi que des gènes candidats dont la fonction dans le développement pigmentaire reste à élucider. L’identification de nouveaux gènes impliqués dans l’AOC pourrait permettre de mieux comprendre et de mieux prendre en charge les patients avec un AOC. / Our work focused on oculocutaneous albinism (OCA) by studying its clinical and molecular aspects. Despite a thorough analysis of the known genes involved in oculocutaneous albinism, 15% of patients remain without diagnostic at the molecular level indicating that mutations are located in unexplored regions and are undetected by standard techniques or that other genes are involved in albinism. We established a clinicomolecular database describing more than 400 patients and developped molecular tools in order to improve molecular diagnostic including a custom high resolution array-CGH dedicated to the four OCA genes (TYR, OCA2, TYRP1 and SLC45A2). We also used different strategies to identify new genes. Array-CGH allows us to detect large deletion in TYR, OCA2 and SLC45A2 and a complexe rearrangement in OCA2 in 2 unrelated patients. We identified, in 5 patients presenting with a non syndromic OCA, mutations in SLC24A5, recently associated with OCA6. Exome sequencing of 6 different patients allows us to identify candidate genes, for which further studies are required to confirm their involvement in OCA pathogenesis. The results of this work allowed us to delineate clinical and genetics aspects of more than 400 OCA patients and to identify new molecular mechanisms leading to OCA and candidates genes for which exact nature of their functions has to be understood. Giving the complexity of pigmentary system development and its regulation, identification of new genes leading to OCA could help to better understand OCA and take care of patients