Mutações nos genes envolvidos na embriogênese hipofisária já foram descritas relacionadas a quadros isolados de deficiência hormonal múltipla e/ou associado a fenótipos extra-pituitários. As mutações encontradas em humanos foram descritas em genes envolvidos na embriogênese hipofisária e cujos fenótipos foram gerados em animais a partir de nocaute, servindo de ponto de partida para sua busca em pacientes com fenótipo similar. Essa estratégia é conhecida como busca por gene candidato, e é feita pela técnica de sequenciamento tradicional Sanger. Na última década, com o avanço de novas tecnologias de sequenciamento, diversos genes foram associados ao hipopituitarismo, principalmente utilizando-se a metodologia de exoma. Contudo, ainda há uma grande parcela dessa população sem diagnóstico molecular, como evidenciado em um levantamento na literatura por Fang e colaboradores e cuja tendência foi observada no ambulatório de Endocrinologia do Desenvolvimento do Hospital das Clínicas, onde apenas 14% dos pacientes tiveram o seu diagnóstico molecular determinado. Com isso, as tecnologias de sequenciamento de última geração, passaram a ser uma ferramenta promissora para determinação molecular dos fenótipos dos pacientes. Logo, alguns pacientes em seguimento no ambulatório de endocrinologia do desenvolvimento tiveram o exoma sequenciado, e uma análise das métricas do sequenciamento evidenciou regiões de cobertura muito baixa, o que não permitiu a conclusão sobre a presença ou ausência de variantes nessas regiões. Entre essas regiões estão os genes SOX2 e SOX3, os quais possuem variantes conhecidas causadoras do fenótipo. Esse trabalho tem como objetivo analisar a cobertura dos genes envolvidos na embriogênese hipofisária assim como os relacionados ao hipopituitarismo congênito em quatro diferentes kits de preparação de biblioteca para exoma, a fim de identificar a melhor metodologia para um diagnóstico molecular dos pacientes alem determinar variantes especificas da população brasileira na região de interesse através de busca no site ABraOM. Foram analisados 76 genes em um total de 119 amostras separadas em três grupos, sendo o primeiro grupo de amostras HapMap, o segundo de um paciente com hipopituitarismo e sua mãe e o terceiro de amostras brasileiras aleatórias. Os kits utilizados foram NimbleGen (Roche), Nextera (Illumina), SureSelect e SureSelect+UTR (Agilent). Para isso, foram utilizados diversos programas de bioinformática, tendo entre eles o FASTQC, BWA, GATK, Annovar, Qualimap e bedTools. Análises da qualidade do sequenciamento, assim como a taxa de mapeamento e duplicação mostraram que as amostras utilizadas apresentavam qualidades adequadas e similares entre si para a análise. De acordo com os resultados obtidos em relação a cobertura, o kit da NimbleGen apresenta uma queda em sua cobertura dos genes de interesse em relação a sua capacidade de cobertura do exoma global, algo que pode ser devido à alta taxa de GC na região de interesse, uma vez que a capacidade do kit nessas regiões é deficiente em relação aos demais. Os genes com piores coberturas em todas as quatro tecnologias foram os genes HES5, que apesar de fazer parte da embriologia hipofisária, não possui variante relacionada ao fenótipo em humanos, e o SOX3 que, apesar de ter muita baixa cobertura na NimbleGen, é bem coberto na SureSelect. Isso corrobora com a análise de capacidade de cobertura em regiões com alta taxa de GC. Somado a isso observou-se que a população brasileira tem 885 variantes únicas e exclusivas. Concluímos, portanto, que o kit SureSelect, da Agilent, tem o melhor desempenho na região de interesse, assim como no exoma global, sendo o indicado para estudos em coortes de hipopituitarismo e a população brasileira possui variantes únicas inerentes a ela / Mutations in the genes involved in pituitary embryogenesis have been described related to isolated cases of multiple hormonal deficiency and/or associated with extra-pituitary phenotypes. Mutations found in humans were described in genes involved in pituitary embryogenesis by generating phenotypes knockout animals, serving as the starting point for their search in patients with similar phenotype. This strategy is known as gene candidate search and is performed by the traditional Sanger sequencing technique. In the last decade, with the advancement of new sequencing technologies, several genes have been associated with hypopituitarism, mainly using the exome methodology. However, there is still a large portion of this population without molecular diagnosis, as evidenced by a survey in the literature by Fang et al., This trend was also observed in the outpatient clinic of Developmental Endocrinology of Hospital das Clínicas, where only 14% of the patients had their molecular diagnosis. With this, high throughput sequencing technologies have become a promising tool for the molecular determination of patients\' phenotypes. Therefore, we sequenced the exome of some of our patients, and an analysis of the sequencing quality showed very low coverage regions, which harms the researcher\'s ability to reach a conclusion regarding presence or lack of variants in these regions. Among these regions are the SOX2 and SOX3 genes, which have many variants that are known to cause the phenotype. This work aims to analyze the coverage of the genes involved in pituitary embryogenesis as well as those related to congenital hypopituitarism in four different exome library preparation kits in order to identify the best methodology for a molecular diagnosis of the patients and to determine specific variants of the Brazilian population in the region of interest by searching the ABraOM website. A total of 76 genes were analyzed in a total of 119 samples in three groups: the first group of HapMap samples, the second of a patient with hypopituitarism and his mother, and the third group of random Brazilian samples. The kits used were NimbleGen (Roche), Nextera (Illumina), SureSelect and SureSelect + UTR (Agilent). For this, several bioinformatics programs were used, among them FASTQC, BWA, GATK, Annovar, Qualimap and bedTools. Sequencing quality analysis, as well as the mapping and duplication rate, showed that the samples used presented adequate and similar qualities for the comparison. According to the results obtained in relation to the coverage, the NimbleGen kit shows a drop in its coverage of the genes of interest in relation to its capacity to cover the global exome, something that may be due to the high GC rate in the region of interest, once the capacity of the kit in these regions is not as good as the others. The genes with the worst coverage in all four technologies were the HES5 gene, which despite being part of the pituitary embryology, have no phenotype-related variant in humans, and SOX3 which, despite having very low coverage in NimbleGen, is well covered on SureSelect. This corroborates the analysis of coverage capacity in regions with a high GC rate. In addition to this it was observed that the Brazilian population has 885 unique and exclusive variants. Therefore, we conclude that the Agilent\'s SureSelect kit has the best performance in the region of interest, as well as in the global exome, being recommended for studies in hypopituitarism cohorts, and that the Brazilian population has unique variants inherent to it

Le système immunitaire est particulièrement dépendant des mécanismes de réparation de l’ADN, en effet le développement du système immunitaire adaptatif nécessite certains mécanismes de réparation de l’ADN, lors de la recombinaison V(D)J et lors de la commutation de classe des immunoglobulines. De plus, le système hématopoïétique est par sa nature très sensible aux lésions spontanées de l’ADN. Il existe chez l’homme de nombreux déficits immunitaires directement liés à un défaut de réparation de l’ADN. L’identification du gène responsable est importante pour un conseil génétique familial approprié et pour la prise en charge médicale. Nous avons accès aujourd’hui à de puissants outils de dépistage génétique grâce au séquençage à haut débit et la liste des gènes responsables d’un déficit immunitaire s’allonge de plus en plus en rapidement. La première partie de ce travail porte sur la mise au point d’un nouvel outil de dépistage rapide des déficits de la réparation de l’ADN, en particulier dans le cas de déficit immunitaires. Ce test est fondé sur l’observation d’un biais du répertoire du TCRdes lymphocytes T circulants lorsque les thymocytes ont une durée de vie diminuée, or un défaut de réparation de l’ADN entraîne une diminution de la survie thymocytaire. Nous avons mis au point deux techniques, par biologie moléculaire et par cytométrie en flux, pour détecter un éventuel biais du répertoire du TCRα et évaluer la pertinence de ce test dans les déficits immunitaires liés à un défaut de réparation de l’ADN. Un biais a notamment été détecté dans les cas de déficit en facteur du NHEJ et en ATM. Nous avons également établi en collaboration avec le service d’Immunologie Clinique de l’hôpital Saint-Louis une cohorte de patients atteints de déficit immunitaire commun variable (DICV) dont la présentation clinique est évocatrice d’un défaut de réparation de l’ADN. Une série de test fonctionnels de dépistages de déficit de la réparation de l’ADN ainsi que des analyses génétiques (CGH array, séquençage complet de l’exome) ont été fait chez ces patients afin d’identifier de nouveaux gènes impliqués dans les DICV. Parmi les 18 patients analysés, dans 5 cas on retrouve une sensibilité cellulaire accrue aux agents génotoxiques et chez 15 patients, un gène candidat a été identifié. Ces résultats sont encore préliminaires et la caractérisation génétique et fonctionnelle des mutations identifiées sera poursuivie par notre équipe. Pour finir, nous avons entrepris l’exploration génétique et fonctionnelle de deux mutations identifiées chez une jeune patiente atteinte de déficit immunitaire combiné (CID) associé à un syndrome lymphoprolifératif et une auto-immunité, et chez qui une hypersensibilité cellulaire à la Mitomycine C, agent pontant de l’ADN, a été détectée. La première mutation a été identifiée dans le gène ELKS qui code pour un facteur impliqué dans la réparation de l’ADN. La complémentation fonctionnelle de ce gène prouve l’implication de cette mutation dans l’hypersensibilité des cellules de la patiente à la MMC. Nous avons développé un modèle murin KO conditionnel de ce gène dans les cellules hématopoïétiques qui n’a pas montré de défaut de développement du système immunitaire. La deuxième mutation identifiée se situe dans le gène BACH2 codant pour un répresseur transcriptionnel très impliqué dans le développement du système immunitaire. Les souris KO pour ce gène ont un phénotype proche du déficit immunitaire décrit chez cette patiente. Les investigations de cette mutation sont en cours chez elle et chez les membres de sa famille également porteurs de la mutation. / The immune system is particularly dependent on DNA damage response (DDR) pathways. The development of the adaptive immune system requires certain DDR mechanisms, in particular during the V(D)J recombination and during class switch recombination (CSR), furthermore, the hematopoietic system is very sensitive to spontaneous DNA lesions. Therefore, there are many immune deficiencies in human directly related to a DDR deficiency. The identification of the responsible gene is important for appropriate genetic counseling. Today, we have access to powerful genetic screening tools, in particular next generation sequencing (NGS) and the list of genes responsible for immune deficiency is growing rapidly. The first part of this work focuses on the development of a new screening tool for DDR defects, in particular in the case of immune deficiency, and evaluation of clinical interest. This test is based on the observation of a bias of the TCRα repertoire in circulating T lymphocytes when thymocytes lifespan is diminished and we know that DDR defect causes decreased thymocyte survival. We have developed two techniques, by molecular biology and by flow cytometry, to detect a potential bias of the TCRα repetoire and assess the suitability of this test in some immunodeficiencies linked to a DDR defect. A significant bias was detected in the case of ATM and NHEJ factor deficiency. Furthermore, we have established a cohort of patients suffering from common variable immunodeficiency (CVID) with a clinical presentation highly suggestive of DDR defect, in collaboration with the Clinical Immunology Service of Hôpital Saint-Louis (Paris). Functional test for DDR defect and genetic analysis (CGHarray, whole exome sequencing) were performed in these patients to identify new genes involved in CVID. Among the 18 patients analyzed until now, five cases of cellular sensitivity to genotoxic agents have been detected and a candidate gene was identified in 15 of them. These results are still preliminary and our team will pursue genetic and functional characterization of the identified mutations. Finally, we undertook genetic and functional exploration of two mutations identified in a young patient with combined immunodeficiency (CID) associated with a lymphoproliferative disease and autoimmunity, and in whom a cellular hypersensitivity to mitomycin C, a DNA crosslinking agent, was detected. The first mutation was identified in the ELKS gene, which codes for a factor involved in DNA repair. Functional complementation of this gene demonstrates the involvement of this mutation in the hypersensitivity of patient’s cells to MMC. We have developed a conditional knockout mouse model of this gene in hematopoietic cells that did not show any defect in development of the immune system. The second mutation was identified in BACH2 gene encoding a transcriptional repressor involved in the development of the immune system. Knockout mice for this gene have a similar phenotype to the immune deficiency described in this patient. Investigations on this mutation are ongoing in the patient and among family members that also carry the mutation.

Submitted by Sara Ribeiro (sara.ribeiro@ucb.br) on 2017-04-20T13:30:09Z No. of bitstreams: 1 FelipeAlbuquerqueMarquesTese2015.pdf: 5827285 bytes, checksum: 3dfbabb913ebff137b6f41b2cd1ba5fc (MD5) / Approved for entry into archive by Sara Ribeiro (sara.ribeiro@ucb.br) on 2017-04-20T13:30:28Z (GMT) No. of bitstreams: 1 FelipeAlbuquerqueMarquesTese2015.pdf: 5827285 bytes, checksum: 3dfbabb913ebff137b6f41b2cd1ba5fc (MD5) / Made available in DSpace on 2017-04-20T13:30:28Z (GMT). No. of bitstreams: 1 FelipeAlbuquerqueMarquesTese2015.pdf: 5827285 bytes, checksum: 3dfbabb913ebff137b6f41b2cd1ba5fc (MD5) Previous issue date: 2015-09-25 / Genetic diseases of the skeleton affect the genesis of skeletal system. They are caused by mutations in genes which act on the cartilage and/or growth plate. The current classification of skeletal anomalies describes more than 456 distinct phenotypes organized into 40 groups. Of this total, 360 phenotypes are associated with defects in 336 genes (thus, 90 diseases remain to have their cause elucidated). The development of high resolution techniques for genomic analysis has enabled more genetic diseases, including skeletal phenotypes, to have molecular basis clarified. This research aimed to identify genes or regions in the human genome associated with genetic diseases of the skeleton. To this end, a pipeline was developed involving experiments and data analysis. Investigation of single nucletoide variation (SNV) was carried out using whole exome sequencing (WES) and submicroscopic structural variations were analyzed by Chromossomal Microarray Analysis (CMA). Moreover, Sanger sequencing, Fluorescence in situ Hybridization, in vitro functional tests (cell culture, qRT-PCR, Western Blot, Immunofluorescence and transcriptome), Immunohistochemistry and histochemistry were employed. 14 patients with rare diseases of skeleton (Craniosynostosis, s. FATCO sindrome, Catel-Manzke-like sindrome, Nager Syndrome and Rodriguez Syndrome) were selected. Craniosynostosis: of three patients, two had their molecular diagnoses elucidated, one with mutation in FGFR3 and the other with a translocation involving chromosomes 17q and 20q. s. FATCO: it wasn't possible to identify the causative mutation for this disease. Catel-Manzke-like Syndrome: initially this patient was diagnosed as Catel-Manzke Syndrome, and there was found a mutation in EXT2. Thus, this patient was reclassified as a new syndrome recently reported as seizures-scoliosis-macrocephaly. Nager and Rodriguez Syndrome: two of four have been diagnosed with mutation in SF3B4. For these patients, the results of qRT-PCR, Western Blot and Immunofluorescence together suggested that the phenotype is caused by SF3B4 haploinsuficiency. Immunohistochemistry and Histochemistry showed the expression of SF3B4 in cartilage tissue and the disorganization of hypertrophic cells in growth plate, respectively. The transcriptome result from cartilage tissue of one patient with SF3B4 mutation showed 12 underexpressed genes involved in skeletogeneses. The combination of techniques like classical cytogenetics and molecular cytogenetics as well as sequencing and in vitro assays were effective to achieve a diagnosis. Although there was an investigative core common to all diseases, investigations were customized to each case, seeking greater efficiency in the detection of the molecular basis and cost optimization of molecular research. / As doen??as gen??ticas do esqueleto s??o anomalias que envolvem a g??nese do sistema esquel??tico, causadas por altera????es em genes que atuam principalmente na cartilagem e/ou no n??cleo de crescimento. Na classifica????o atual h?? 456 doen??as do esqueleto categorizadas em 40 grupos. Destes, 360 patologias esquel??ticas est??o associadas a defeitos em 336 genes (portanto, existem 90 displasias esquel??ticas sem causa definida). O surgimento de t??cnicas de alta resolu????o de an??lise gen??mica tem permitido que cada vez mais doen??as gen??ticas, incluindo as doen??as gen??ticas do esqueleto, possam ter suas bases moleculares elucidadas. Esta pesquisa teve como objetivo a identifica????o e caracteriza????o de genes e regi??es do genoma humano associado a doen??as gen??ticas raras do esqueleto. Para isso, implantou-se um pipeline envolvendo experimentos e an??lise de dados. Esta tese investigou varia????es de nucleot??deo ??nico (SNVs) pelo uso Whole Exome Sequencing (WES) e varia????es estruturais submicrosc??picas, pelo uso Chromossomal Microarray Analysis (CMA). Al??m disso, fez-se uso de Sequenciamento de Sanger, Fluorescence in situ Hybridization, testes funcionais in vitro (cultura celular, qRT-PCR, Western Blot, Imunofluoresc??ncia e Transcritoma), Imunohistoqu??ca e histoqu??mica. Foram selecionados 14 pacientes com doen??as raras do esqueleto (Craniossinostose, s??ndrome FATCO, s??ndrome Catel-Manzke-like, s??ndrome de Nager e s??ndrome Rodriguez). Craniossinostose: dos quatro pacientes, dois foram diagnosticados com muta????o em FGFR3 e outro com uma transloca????o envolvendo os cromossomos 17q e 20q. S??ndrome de FATCO: n??o foi poss??vel identificar as bases moleculares da doen??a. ???Catel-Manzke-Like???: inicialmente diagnosticado com Sindrome de Catel-Manzke, o paciente teve uma muta????o detectada em EXT2, sendo reclassificado como uma nova s??ndrome (S??ndrome Convuls??o-Escoliose-Microcefalia). S??ndromes de Nager e Rodriguez: foram diagnosticado muta????es no gene SF3B4 em dois dos quatro pacientes. Nestes mesmos pacientes foram realizados qTR-PCR, Western Blot e Imunofluoresc??ncia que juntos sugeriram que estas patologias sejam causadas pela haploinsufici??ncia do SF3B4. A imunohistoqu??mica e histoqu??mica mostraram a express??o de SF3B4 na placa de crescimento e desorganiza????o de condr??citos hipertr??ficos, respectivamente. O transcritoma de um dos pacientes, com muta????o em SF3B4, evidenciou 12 genes ligados a esqueletog??nese com express??o diminu??da no tecido cartilaginoso. A combina????o de t??cnicas seja citogen??tica cl??ssica, citogen??tica molecular, sequenciamento, bem como an??lises in vitro se mostraram eficientes para se alcan??ar o diagn??stico. Embora houvesse um cerne investigativo em comum a todas as doen??as, as investiga????es foram personalizadas para cada caso, visando maior efici??ncia na detec????o das bases moleculares e otimiza????o dos custos da investiga????o molecular.

A imunodeficiência combinada grave (SCID) é uma doença caracterizada por profunda deficiência de células T, que afeta as imunidades celular e humoral e gera anormalidades graves no desenvolvimento e funções do sistema imune. Recém-nascidos com SCID apresentam a doença nos primeiros meses de vida e tem grande susceptibilidade a infecções. Sem tratamento, essas condições são invariavelmente fatais, porém se reconhecidas precocemente, há a possibilidade da realização do transplante de células-tronco hematopoiéticas, o tratamento curativo, o que torna a SCID uma emergência pediátrica. A investigação do defeito genético é uma prerrogativa para o condicionamento adequado do transplante, a terapia gênica, o aconselhamento genético e o diagnóstico pré-natal. No Brasil, o conhecimento sobre SCID é incipiente e não existem dados moleculares sobre pacientes com a doença. Sendo assim, este estudo teve por objetivo investigar defeitos genético-moleculares de pacientes brasileiros com SCID. Foram incluídos 13 pacientes, todos com início precoce dos sintomas e manifestações clínicas esperadas em SCID (principalmente infecções respiratórias, de pele, diarreia crônica e atraso de crescimento). Os patógenos isolados foram vírus, bactérias e fungos oportunistas comumente encontrados em pacientes SCID. A partir da quantificação de TRECS e KRECs e imunofenotipagem de linfócitos, foi montado o perfil imunológico de cada paciente, que guiou o sequenciamento direto de Sangerdos genes mais frequentemente mutados em cada imunofenótipo de SCID. Mutações em 3 pacientes foram identificadas por Sanger e, posteriormente, 8 pacientes cujas mutações não foram encontradas no Sanger foram encaminhados para o sequenciamento completo de exoma, que resultou na identificação do gene afetado em 62,5% dos casos. Ao todo, foram identificadas mutações patogênicas em 8 dos 13 pacientes. Os resultados revelaram 6 alterações em 5 genes de SCID clássica (IL7R, RAG2, DCLRE1C, JAK3, IL2RG), 1 mutação no gene CD3G e 2 alterações em CECR1. Das 9 mutações encontradas, 5 não possuíam registro na literatura. O estudo genético de SCID em nosso país é problemático, principalmente porque ainda hoje, a esmagadora maioria dos pacientes não é diagnosticada. A implementação da quantificação de TRECs e KRECs como triagem neonatal para linfopenias graves é uma ferramenta fundamental para que os pacientes SCID possam ser identificados, investigados e tratados adequadamente. / Primary immunodeficiencies are a heterogeneous group of genetic diseases that lead to increased susceptibility to infections and affect mostly children. Severe Combined Immunodeficiency (SCID) is the most severe of all these diseases and is characterized by profound T cell deficiency, which affects cellular and humoral immunities and leads to severe abnormalities in the development and function of the immune system. Newborns with SCID present the disease in the first months of life and are highly susceptible to infections. Without treatment, these conditions are invariably fatal, but if recognized early, there is the possibility of hematopoietic stem cell transplantation, the curative treatment, which makes SCID a pediatric emergency. Identifying the genetic defect of SCID patients is a prerequisite for proper transplant conditioning, gene therapy, genetic counseling and prenatal diagnosis. Knowledge about SCID is still incipient in Brazil, and there are virtually no molecular data on patients with the disease. Therefore, this study aimed to investigate genetic-molecular defects of Brazilian patients with SCID. Thirteen patients were recruited, all with early onset of symptoms and clinical manifestations expected of classic SCIDs (mainly respiratory and skin infections, chronic diarrhea and failure to thrive). The pathogens isolated were opportunistic viruses, bacteria and fungi often reported in SCID patients. The immunological profile from each patient was defined by the quantification of TRECS and KRECs and lymphocyte immunophenotyping, which was meant to guide direct sequencing by Sanger of the most frequently mutated genes of each SCID immunophenotype. Mutations in 3 patients were identified by Sanger and, subsequently, 8 patients whose mutations were not identified by Sanger were referred for whole exome sequencing, which resulted in the identification of the affected gene in 62,5% of cases. Pathogenic mutations were identified in 8 of the 13 patients. The results revealed 6 mutations in 5 genes associated to classical SCID genes (IL7R, RAG2, DCLRE1C, JAK3, IL2RG), 1 mutation in the CD3G gene, and 2 mutations in CECR1. Five of the 9 mutations found had no record in the literature. SCID genetic investigation in our country is troublesome, mainly because even nowadays, the vast majority of patients are not diagnosed properly. Newborn screening for SCID and other severe lymphopenias by the quantification of TRECs and KRECs is key for the identification, investigation and proper treatment of SCID patients.

No description available.

L’Hypertension Hyperkaliémique Familiale (HHF) est une forme rare d’hypertension associée à une hyperkaliémie et une acidose métabolique hyperchlorémique, très sensible aux diurétiques thiazidiques. Les premières analyses génétiques ont permis d’identifier deux gènes responsables, WNK1 et WNK4, mais qui n’expliquaient que 8 % de notre cohorte. L’objectif de ma thèse était de rechercher de nouveaux gènes ou variants à l’origine de l’HHF. Notre stratégie initiale a été de combiner une analyse de liaison à un séquençage d’exome entier sur trois grandes familles atteintes. Nous avons ainsi identifié un nouveau gène responsable de la maladie codant pour un acteur jusque là insoupçonné, KLHL3 (Kelch-like 3), responsable de 39% des cas de notre cohorte. La majorité des mutations sont présentes à l’état hétérozygote entrainant un phénotype modéré, alors que les rares patients porteurs d’une mutation homozygote, tous issus de familles consanguines, présentent un phénotype plus marqué. Le spectre des mutations a montré l’importance des structures en boucles de cette protéine qui joue un rôle d’adaptateur de substrat dans un complexe d’ubiquitination (publié dans Nature Genetics, 2012). La découverte d’un type unique de mutations sur le gène CUL-3 par une équipe concurrente a été confirmée dans notre cohorte, entrainant un phénotype plus précoce et plus sévère. Ces mutations ont mis en lumière l’importance de ces deux protéines dans la constitution du complexe E3 ubiquitine-ligase et la dégradation des WNKs dans le néphron, par le protéasome après ubiquitination. Nous avons aussi identifié des mutations faux-sens dans le domaine acide de WNK1 très conservé chez des patients ayant un phénotype HHF mais sans hypertension artérielle. Ce motif, similaire à celui porteur de mutations sur WNK4 est responsable de la liaison à l’adaptateur de substrat KLHL3. Les sujets atteints présentent un âge plus précoce d’apparition de la maladie avec des valeurs de pression artérielle normales. La comparaison phénotypique avec les cas porteurs d’une mutation WNK4 et d’une délétion de l’intron 1 de WNK1 a montré des différences de pression artérielle significatives. La transfection d’ARNc mutés dans les œufs de Xénope, effectuées en collaboration, a permis de démontrer que ces nouvelles mutations faux-sens de WNK1 entrainent une accumulation de son isoforme rénale KS-WNK1 (soumis à J Am Soc Nephrol). L’ensemble de ces résultats ouvre une nouvelle voie de compréhension moléculaire de la régulation du transport des ions sodium, potassium et chlore au niveau du rein et par conséquence de la pression artérielle. / Familial Hyperkalemia Hypertension (FHHt), also known as Gordon syndrome is a rare form of hypertension associated with hyperkalemia and hyperchloremic metabolic acidosis, very sensitive to thiazide diuretics. In 2001, the first genetic analysis identified two genes, coding for two serine/threonine kinases WNK1 and WNK4, which explained only 8% of our cohort. The aim of my thesis was to search new genes or variants responsible for FHHt. We decided to combine a linkage analysis and a whole exome sequencing in three affected families. We identified a new gene responsible for the disease coding for an unsuspected actor KLHL3 (Kelch-like 3), responsible for 39% of our cohort. The majority of the mutations are present at a heterozygous state leading to a moderate phenotype, whereas patients with homozygous mutation, all from consanguineous families, displayed a stronger phenotype. The spectrum of mutations showed the importance of the loop structures of this protein playing an adaptor role in an ubiquitination complex (published in Nature Genetics, 2012). The discovery of a particular type of mutations in CUL-3 by another team was confirmed in our cohort, leading to an earlier and more severe phenotype. These changes have highlighted the importance of these two proteins in the formation of the E3 ubiquitin-ligase-complex and in the WNKs degradation in the nephron by the proteasome after ubiquitination. We have also identified missense mutations in the acidic motif of WNK1, highly conserved in patients with FHHt without hypertension. This pattern is similar to the WNK4 mutations and is responsible for the binding of the substrate adaptor KLHL3. Affected individuals have an earlier age of onset with normal blood pressure values for most of them. Phenotypic comparison with cases carrying WNK4 mutations and deletion of the intron 1 of WNK1 showed significant differences in blood pressure values. Transfection of mutated cRNA in Xenopus laevis oocyte demonstrated that these new WNK1 missense mutations result in the accumulation of the renal isoform KS-WNK1 (submitted to J Am Soc Nephrol). Taken together, these results open a new pathway for understanding the molecular regulation of ion transport and WNK kinases in the kidney and consequently the regulation of blood pressure.

La pratique du mariage entre apparentés au sein de la population libanaise, favorisée par des raisons sociales, religieuses, géographiques et aussi politiques, a vu apparaître des sous-groupes de populations de taille plus ou moins réduite, parfois à la limite d’isolats génétiques. Ceci a engendré une augmentation de la prévalence des maladies autosomiques récessives fréquentes mais aussi et surtout rares. Parmi ces dernières, les chondrodysplasies ont retenu notre attention. Elles sont caractérisées par un retard statural dû à un défaut du processus d’ossification endochondale, qui est responsable de la croissance des os longs. Au cours de ces dernières décennies, plus de 230 gènes responsables d’environ 400 maladies osseuses constitutionnelles ont été identifiés. Cependant, les bases moléculaires d'une centaine de dysplasies osseuses restent, à ce jour, inconnues. L’identification de gènes codant pour des protéines de nature extrêmement variée a contribué à la compréhension du mécanisme complexe d’ossification endochondrale. Mon travail de thèse, réalisé en cotutelle entre l’équipe de recherche « Bases moléculaires et physiopathologiques des chondrodysplasies » de l’hôpital Necker enfants-malades, à Paris en France et l’Unité de Génétique Médicale (UGM) de l’Université Saint-Joseph au Liban, a consisté à identifier des gènes impliqués dans des dysplasies osseuses autosomiques récessives dans quatre familles libanaises consanguines. Dans ce cadre, différentes stratégies ont été adoptées. La première a été une stratégie d’intersection des variations détectées par le séquençage de l’exome de deux patients, atteints d’une forme sévère de dysplasie spondylodysplastique létale et issus de deux familles libanaises consanguines et non apparentées (Familles A et B). Nous avons identifié une mutation homozygote du gène MAGMAS (NM_016069, p.Asn76Asp) (Mitochondria-associated granulocyte macrophage CSF-signaling molecule) à l’origine de la maladie dans les deux familles A et B. MAGMAS est une protéine associée à la mitochondrie et impliquée dans la régulation de l’import actif des protéines vers la matrice mitochondriale. Par immunohistochimie, nous avons montré que MAGMAS est spécifiquement exprimée au niveau de l’os et de la zone hypertrophique du cartilage. MAGMAS, ayant une fonction cruciale pour la survie, est très conservé entre les espèces. Après avoir généré des souches de levures exprimant une copie normale ou mutée du gène humain MAGMAS, nous avons validé l’effet délétère de la mutation p.Asn76Asp, i) sur la croissance des levures, en montrant que les souches portant le gène humain muté présentent un caractère thermosensible, ii) sur la fonction d’import des protéines vers la matrice mitochondriale, qui est altérée dans les souches mutées et iii) sur la stabilité de la protéine. Nous avons également observé un effet de la mutation sur la morphologie des mitochondries et des peroxysomes des cellules de levures, suggérant une induction de l’autophagie dans les souches de levures portant la mutation p.Asn76Asp. L’identification de mutations de MAGMAS dans une dysplasie osseuse sévère, permet d’attribuer à cette protéine un rôle spécifique dans le processus complexe d’ossification endochondrale. La deuxième stratégie a été une combinaison, au sein d’une même famille, d’une stratégie de cartographie par homozygotie et du séquençage de l’exome d’un seul patient. Cette approche a été utilisée dans une famille consanguine avec 3 enfants atteints porteurs d’une dysplasie rhizomélique (Famille C). Nous avons identifié une mutation homozygote du gène NWD1 (NACHT and WD repeat domain containing 1) (NM_001007525, p.Cys1376Tyr) responsable de la maladie dans cette famille C. Ce gène code pour une protéine ayant des domaines WD répétés qui lui confèrent un rôle dans divers mécanismes comme la transduction de signal, la régulation de la transcription, le transport vésiculaire et le contrôle du cycle cellulaire. (...) / Social, religious, geographic and political reasons have favored the consanguineous marriage in the Lebanese population. This led to an increase in the prevalence of autosomal recessive disorders, especially the rare entities including chondrodysplasias. This group of diseases is due to an impairment of the endochondral ossification process. Causative mutations have now been identified in over 230 different genes in more than 400 unique skeletal phenotypes. However, the genetic basis of over 100 different entities remains to be determined. My PhD research project, held between the research group « Bases moléculaires et physiopathologiques des chondrodysplasies » of Necker enfants-malades hospital (INSERM U781, PARIS, France) and the Medical Genetics Unit of Saint-Joseph University (Lebanon), aims to identify genes involved in autosomal recessive skeletal dysplasias in four consanguineous Lebanese families. Different strategies were carried out: the first consists in overlapping data from whole exome sequencing of two patients affected by a new lethal type of spondylodysplastic dysplasia and issued from two consanguineous unrelated Lebanese families (Families A and B). Here, we report a homozygous missense mutation in the Mitochondria-associated granulocyte macrophage CSF-signaling gene (MAGMAS: NM_016069, p.Asn76Asp) in this severe skeletal dysplasia. MAGMAS, also referred to as PAM16, is a mitochondria-associated protein, involved in pre-proteins import into mitochondria and essential for cell growth and development. We demonstrate that MAGMAS is expressed in trabecular bone and cartilage at early developmental stages underlining its specific role in skeletogenesis. We also give strong evidence of the deleterious effect of the identified mutation on the stability of the protein, its in-vivo activity and the viability of yeast strains. We also show that the mutation is able to induce autophagy in yeast cells. Reporting deleterious MAGMAS mutation in a skeletal dysplasia supports a key and specific role for this mitochondrial protein in ossification. Additional studies would be of interest to further understand the specific role of magmas in ossification. The second strategy was to combine, in a consanguineous family, homozygosity mapping with whole exome sequencing of one of the patients. This strategy was undertaken in family C with 3 patients affected by a rhizomelic dysplasia. It allowed us to identify a homozygous missense mutation in the NWD1 gene (NACHT and WD repeat domain containing 1: NM_001007525, p.Cys1376Tyr) as responsible for the skeletal dysplasia in this family. NWD1 belongs to a large group of WD-repeat domain-containing proteins that are involved in different physiological mechanisms such as signal transduction, transcription regulation, vesicular transport and cell cycle control. (...)

La malformation anévrysmale de la veine de Galien (MAVG) est une malformation vasculaire cérébrale congénitale qui représente près d’un tiers des anomalies vasculaires pédiatriques. Au sein d’une cohorte de 51 patients atteints d’une MAVG, nous avons identifié 5 individus porteurs de mutations hétérozygotes pathogéniques d’EPHB4. Ces mutations incluent une mutation tronquante survenue de novo ainsi que des mutations d’épissage et faux-sens hétérozygotes délétères héritées d’un parent. L’invalidation d’EPHB4 chez les embryons de Danio rerio est à l’origine d’anomalies vasculaires cérébrales spécifiques impliquant la veine dorsale longitudinale, la veine orthologue médiane du prosencéphale (précurseur embryonnaire de la veine de Galien). La co-injection de l’ARNm tronqué a permis la restauration d’un phénotype sauvage démontrant que le phénotype vasculaire observé est la conséquence d’une perte de fonction d’EPHB4. L’ensemble de ces données indique qu’EPHB4 est un gène déterminant chez un sous-groupe de patients atteints d’une MAVG, comme chez Danio rerio. Les mutations perte de fonction d’EPHB4 sont à l’origine d’anomalies spécifiques du développement vasculaire cérébral. L’identification de mutations pathogéniques d’EPHB4 chez des patients présentant des malformations capillaires implique une surveillance attentive de la grossesse. Cette surveillance échographique renforcée pourrait permettre la détection précoce d’une MAVG et une prise en charge anténatale et néonatale optimale. / Vein of Galen aneurysmal malformation (VGAM) is one of the most common fetal brain vascular malformations. We conducted whole exome sequencing in 19 unrelated VGAM patients and subsequently screened candidate gene in a cohort of 32 additional patients. We found 5 affected individuals with heterozygous mutations in EPHB4 including de novo frameshift or inherited deleterious splice or missense mutations predicted to be pathogenic by in silico tools. Knockdown of EPHB4 in zebrafish embryos leads to specific anomalies of dorsal cranial vessels including dorsal longitudinal vein, the ortholog of the median prosencephalic vein, the embryonic precursor of the vein of Galen. This model allowed todemonstrate EPHB4 loss of function mutations in VGAM by the ability to rescue the brain vascular defect in knockdown zebrafish co-injected with wild type but not truncated EPHB4 mimicking the frameshift mutation. Our data showed that in both species, loss of function mutations of EPHB4 result in specific and similar brain vascular development anomaliesThe identification of EPHB4 pathogenic mutation in patients presenting capillary malformation or VGAM should lead to careful follow up of pregnancy of carriers for early detection of VGAM in order to propose optimal neonatal care. Endovascular embolization indeed greatly improved the prognosis of VGAM patients.

Breast cancer (BCa) is a leading cause of cancer-related female deaths worldwide and is a complex disease consisting of many different subtypes with varying clinical course and outcomes. Triple negative breast cancer (TNBC), an aggressive and highly metastatic subtype, is most prevalent in women of African ancestry (WAA) but the causes of this disparity are not fully understood. The goal of this study was to investigate the epidemiological and genetic profiles in ancestrally-related WAA in Barbados and Nigeria to advance knowledge and lay the foundation for development of improved or novel BCa therapeutics. To gain insight about TNBC across the African continent, a systematic review and meta-analysis was conducted. TNBC frequencies on average across Africa were estimated at 26.8% but were highest in West African countries (46.0%). We also sought to identify the epidemiological profile of BCa in Barbados—a Caribbean island with significant West African ancestry. We reviewed pathological reports for BCa from the sole public hospital in Barbados and compared those data with USA population-based data. We found a high prevalence of high prevalence of TNBC amongst women diagnosed with breast cancer in Barbados (25%), compared to 21% in non-Hispanic Black and 10% in non-Hispanic White women in the USA for the 2010-2016 period. We also investigated the somatic mutational profile of WAA with TNBC in Barbados and Nigeria using whole exome sequencing (WES) of formalin-fixed paraffinembedded TNBC tissues. This investigation revealed novel and pathogenic variants in well-known cancer-associated genes such as TP53, BRCA1 and MDC1. The somatic mutation signature in Nigerian tissues correlated with aflatoxin signature, implying a role for environmental factors influencing the genomics profile in this cohort. Copy number variants were revealed at high frequencies for PIK3CA, FGFR2 and HIF1AN genes. Collectively, these findings uncovered novel epidemiological and genetic trends in WAA with high prevalence of the aggressive TNBC subtype / Thesis / Doctor of Philosophy (PhD) / Breast cancer (BCa) is a leading cause of cancer-related death in women worldwide. Although Caucasian women are diagnosed with BCa more than women of African ancestry (WAA), more WAA unfortunately die from BCa. The reasons for this disparity are currently unknown, however, a higher proportion of WAA are diagnosed with an aggressive type of BCa called triple negative breast cancer (TNBC). This might partially explain the high cancer death rate in WAA. To understand this disparity in BCa incidence and outcomes, we investigated TNBC disease trends across the African continent and in Barbados (a Caribbean island with predominantly African ancestry) and found a high proportion of TNBC diagnoses in Barbados and West African countries. We also discovered a novel genetic profile within these groups that may be useful to develop new cancer therapies that would decrease TNBC aggressiveness and death in these populations.

Die Dissertationsarbeit untersucht genetische Varianten in Zellkulturmodellen des metastatischen und kastrationsresistenten Prostatakarzinoms. Außerdem werden Mechanismen der Chemoresistenz, insbesondere der Resistenz gegen Cisplatin und Docetaxel in diesen Zelllinien untersucht. / This Dissertation evaluates genetic variants found in cell culture models of metastatic castration resistant prostate cancer. Furthermore, mechanisms of resistance against the chemotherapeutic drugs cisplatin and docetaxel are investigated in these cell lines.