Thèse d'exercice : Médecine. Médecine générale : Paris 12 : 2005. / Titre provenant de l'écran-titre. Bibliogr. f. 71-82. Glossaire.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2005. / Härtill 6 uppsatser.

No description available.

<p>Genomic imprinting is the parent-of-origin dependent monoallelic expression of select developmentally important genes that are regulated by epigenetic mechanisms. It is believed to have co-evolved with placentation in the Therian lineage, but it is unclear whether this phenomenon arose in a convergent or divergent manner in the Metatherians (those with a rudimentary placenta) and Eutherians (true placental mammals). Moreover, the precise epigenetic mechanisms involved in establishing genomic imprinting (DNA methylation or histone modifications) are still poorly defined. Thus, I studied Metatherian orthologues of Eutherian imprinted loci using Monodelphis domestica as a model organism. L3MBTL and HTR2A were monoallelically expressed; PEG1/MEST had one imprinted and one non-imprinted transcript, while IMPACT, COPG2 and PLAGL1 were not imprinted, thus revealing that this phenomenon is conserved at some, but not all loci between the two groups of Therians. Moreover, differential methylation patterns and the associated regulatory non-coding RNA are also not conserved amongst them, exemplified by the novel DMR identified within IGF2R which had no associated anti-sense transcript. However, histone modifications, specifically the activating H3 Lysine 4 dimethylation mark at the active allele's promoter seems to be important in both lineages and probably serves as the primordial imprint mark. Although the evidence does not resolve the issue of convergence or divergence, it raises the intriguing possibility that both forms of evolution occurred during establishment of imprinting in these mammals.</p> <p>The imposition of functional haploidy in the genome by such epigenetic mechanisms necessarily makes imprinted genes more susceptible to deleterious mutations and regulatory perturbations. Thus, imprinting is implicated in a number of developmental disorders, but its role in the etiology of complex human diseases and neurological disorders, like autism and schizophrenia, remains to be determined. I chose to investigate the imprint status of the duplicated locus DGCR6/DGCR6L lying within the 22q11.2 microdeletion causative of DiGeorge Syndrome (DGS), because our lab previously predicted genes at this genomic location to be imprinted. My studies revealed that both genes DGCR6 and DGCR6L are monoallelically expressed in the primate lineage, but not in a parent-of-origin dependent manner. Interestingly, DGCR6L is not present in the mouse, and Dgcr6 is expressed from both parental alleles.</p> <p>Although DGS primarily manifests as facial, limb and heart abnormalities in children, a number of these patients also ultimately present with variable neurocognitive defects. Thus, I focused my studies on determining the effect of the microdeletion at this chromosomal region on DGCR6 and DGCR6L expression because of their potential role in neural crest cell migration. This revealed that DGS subjects have a highly dysregulated pattern of DGCR6 and DGCR6L expression as compared to that in controls. Moreover, increased expression of these genes correlated significantly with decreased performance in sustained-attention tests. This provides the first evidence that disruption of the normal monoallelic expression pattern of DGCR6 and DGCR6L by hemizygous deletion is involved in the variability in neurocognitive symptoms associated with DiGeorge Syndrome. The results of my studies highlight the importance of searching for novel imprinted domains to better understand not only their evolution, but also the potential role of such epigenetically labile regions in modulating complex human diseases and neurological disorders.</p> / Dissertation

No description available.

Este estudo investigou a prevalência de disgenesias dentárias, alterações de tecido mole e características cefalométricas em pacientes com síndrome velocardiofacial e síndrome G/BBB. A presença de disgenesias dentárias foi avaliada em pacientes acima de seis anos de idade; para a análise cefalométrica, foram avaliadas telerradiografias laterais obtidas antes de qualquer intervenção ortodôntica. A amostra de estudo para a síndrome velocardiofacial incluiu 26 pacientes para análise de disgenesias dentárias e alterações de tecido mole e 18 pacientes para análise cefalométrica. Para a síndrome G/BBB, foram analisados 21 pacientes quanto à presença de disgenesias dentárias e alterações de tecido mole, e 23 pacientes para a análise cefalométrica. Foram incluídos apenas pacientes de etnia branca. A ocorrência de agenesias dentárias e dentes supranumerários foi comparada a pacientes sem nenhuma alteração morfofuncional, pareados para gênero e idade. Para a análise cefalométrica, as telerradiografias foram traçadas manualmente; os traçados foram digitalizados e as variáveis foram medidas com auxílio do software Dentofacial Planner 7.0. Nesta análise, os pacientes também foram comparados a pacientes sem nenhuma alteração morfofuncional, pareados para gênero e idade. Para a síndrome velocardiofacial, 76,92% dos pacientes apresentaram pelo menos uma disgenesia dentária, com predominância de alterações hipoplasiantes, principalmente representadas por hipodesenvolvimento da cúspide lingual do primeiro pré-molar inferior e opacidades de esmalte; a ocorrência de agenesias dentárias e dentes supranumerários foi semelhante à observada no grupo controle. Na análise cefalométrica, observou-se menor comprimento da base do crânio (total e da parte posterior); retrusão e redução da altura posterior da maxila; aumento do ângulo goníaco; aumento do ângulo interincisal; maior inclinação lingual dos incisivos inferiores; redução do ângulo nasolabial; e redução da profundidade nasal, comparado ao grupo controle. Com relação à síndrome G/BBB, 95,23% dos pacientes apresentaram pelo menos uma disgenesia dentária, com predominância de alterações hipoplasiantes; a freqüência de agenesias dentárias e dentes supranumerários foi significativamente maior comparada ao grupo controle. Foi observada anquiloglossia em 11 de 21 pacientes. A análise cefalométrica revelou aumento do ângulo da base do crânio; maior retrusão dos ossos nasais; encurtamento do ramo, redução do comprimento, e retrusão da mandíbula; maior discrepância maxilomandibular, com maior convexidade facial; maior inclinação lingual dos incisivos inferiores e superiores; padrão de crescimento mais vertical; nariz mais achatado, ponte nasal mais curta, maior retrusão nasal e redução da profundidade nasal, comparado ao grupo controle. Em conclusão, na avaliação de pacientes com hipótese diagnóstica das referidas síndromes, sugere-se investigar a anatomia oclusal de pré-molares inferiores no caso da síndrome velocardiofacial, e a presença de dentes supranumerários anteriores inferiores e anquiloglossia para a síndrome G/BBB. A análise cefalométrica também indicou diferenças significativas em diversas variáveis, simultaneamente servindo como parâmetro na descrição das síndromes e exigindo protocolo de tratamento diferenciado para estes pacientes. / This study investigated the prevalence of tooth abnormalities, soft tissue changes and cephalometric analysis in patients with velocardiofacial syndrome and G/BBB syndrome. The presence of tooth abnormalities was evaluated in patients older than six years; cephalometric analysis was conducted on lateral cephalograms obtained before any orthodontic intervention. The study sample for the velocardiofacial syndrome included 26 patients for analysis of tooth abnormalities and soft tissue changes, and 18 patients for cephalometric analysis. For the G/BBB syndrome, 21 patients were analyzed as to the presence of tooth abnormalities and soft tissue changes, and 23 patients for cephalometric analysis. Only white patients were included. The occurrence of tooth abnormalities and supernumerary teeth was compared to patients without any morphofunctional alterations, matched for gender and age. For cephalometric analysis, the lateral cephalograms were manually traced; tracings were digitized and the variables were measured on the software Dentofacial Planner 7.0. For this analysis, patients were also compared to individuals without malformations, matched for gender and age. For the velocardiofacial syndrome, 76.92% of patients presented at least one tooth abnormality, with predominance of hypoplastic alterations, especially represented by hypodevelopment of the lingual cusp of mandibular first premolars and enamel opacities; the occurrence of tooth agenesis and supernumerary teeth was similar to that observed in the control group. Cephalometric analysis revealed reduced length of the skull base (total and of the posterior portion); retrusion and reduction of posterior height of the maxilla; increased gonial angle; increased interincisal angle; greater lingual inclination of mandibular incisors; reduced nasolabial angle; and reduced nasal depth, compared to the control group. Concerning the G/BBB syndrome, 95.23% of patients presented at least one tooth abnormality, with predominance of hypoplastic alterations; the frequency of tooth agenesis and supernumerary teeth was significantly higher compared to the control group. Ankyloglossia was observed in 11 of 21 patients. Cephalometric analysis revealed increased cranial base angle; greater retrusion of nasal bones; shortening of mandibular ramus, reduced mandibular length, and mandibular retrusion; greater maxillomandibular discrepancy, with greater facial convexity; greater lingual inclination of maxillary and mandibular incisors; more vertical growth pattern; more flattened nose, shorter nasal bridge, greater nasal retrusion and reduced nasal depth, compared to the control group. In conclusion, during evaluation of patients with suspected diagnosis of the syndromes, investigation of the occlusal anatomy of mandibular premolars in case of velocardiofacial syndrome, and of the presence of mandibular anterior supernumerary teeth and ankyloglossia for the G/BBB syndrome are suggested. Cephalometric analysis also indicated significant differences in several variables, simultaneously serving as parameter for description of syndromes and requiring a customized treatment protocol for these patients.

Le syndrome de DiGeorge ou microdélétion 22q11.2, est la délétion chromosomique la plus fréquente chez les êtres humains. Cette délétion est liée à la recombinaison homologue non-allélique au cours de la méiose induisant la perte d’en moyenne 40 gènes. Les études de corrélation génotype/phénotype chez les patients ont révélé des différences phénotypiques entre individus et cela indépendamment de la taille des microdélétions. L’hypothèse de l’implication des mécanismes épigénétiques dans la variabilité phénotypique observée a été soulevée mais reste encore inexplorée. C’est dans ce contexte que nous nous intéressons à l’étude des mécanismes épigénétiques au cours du développement, dans cette pathologie à travers l’utilisation d’un modèle de cellules souches pluripotentes induites humaines (hiPSs). En particulier, nous avons ciblé nos travaux sur le rôle de la chaperonne d’histone HIRA dont le gène est localisé dans la région délétée. HIRA est impliquée dans la déposition du variant d’histone H3.3, une histone majeure dans le cerveau. Afin de comprendre l’implication de HIRA dans les manifestations neurologique du syndrome de DiGeorge et en particulier dans la schizophrénie, nous avons développé et optimisé un nouveau protocole pour la différenciation de cellules hiPSCs en progéniteurs neuronaux, neurones corticaux et neurones dopaminergiques. L’ensemble de ces travaux ouvre donc de nouvelles perspectives pour la modélisation d’un grand nombre de pathologies, et dans le contexte du laboratoire, pour l’exploration des mécanismes épigénétiques associés à la variabilité phénotypique dans différentes maladies génétiques. / The DiGeorge syndrome also known as 22q11.2 microdeletion syndrome, is the most common deletion in humans. This deletion is linked to a non-allelic homologous recombination that occurs during meiosis and involves sequences called LCRs for "Low Copy Repeats". Depending on the LCRs involved, different deletions are observed, inducing the loss of approximately 40 genes. The absence of genotype/phenotype correlation in patients and the phenotypical differences regardless of the size of the microdeletion suggests the involvement of additional parameter. The hypothesis of epigenetic changes associated with the onset or variability of symptoms has been suggested but never investigated. In order to tackle this question, we decided to focus our attention of the role of the HIRA histone chaperone encoded by a gene located in the 22q11.2-deleted region. HIRA is involved in the deposition of the H3.3 histone variant, one of the main histone in the brain. In order to determine whether HIRA is implicated in the neurological manifestations in DiGeorge patients and particularly in schizophrenia, we developed and optimized a new protocol for the direct differentiation of human induced pluripotent stem cell (hiPSCs) into neural progenitors, cortical and dopaminergic neurons. In parallel, we developed a new protocol for hiPSCs differentiation toward the skeletal muscle lineage and the production of multinucleated muscle fibers. Altogether, these results open new perspectives for the modeling of a large number of pathologies, and in the context of our laboratory, the exploration of epigenetic mechanisms associated with phenotypic variability in different genetic diseases.

Este estudo investigou a prevalência de disgenesias dentárias, alterações de tecido mole e características cefalométricas em pacientes com síndrome velocardiofacial e síndrome G/BBB. A presença de disgenesias dentárias foi avaliada em pacientes acima de seis anos de idade; para a análise cefalométrica, foram avaliadas telerradiografias laterais obtidas antes de qualquer intervenção ortodôntica. A amostra de estudo para a síndrome velocardiofacial incluiu 26 pacientes para análise de disgenesias dentárias e alterações de tecido mole e 18 pacientes para análise cefalométrica. Para a síndrome G/BBB, foram analisados 21 pacientes quanto à presença de disgenesias dentárias e alterações de tecido mole, e 23 pacientes para a análise cefalométrica. Foram incluídos apenas pacientes de etnia branca. A ocorrência de agenesias dentárias e dentes supranumerários foi comparada a pacientes sem nenhuma alteração morfofuncional, pareados para gênero e idade. Para a análise cefalométrica, as telerradiografias foram traçadas manualmente; os traçados foram digitalizados e as variáveis foram medidas com auxílio do software Dentofacial Planner 7.0. Nesta análise, os pacientes também foram comparados a pacientes sem nenhuma alteração morfofuncional, pareados para gênero e idade. Para a síndrome velocardiofacial, 76,92% dos pacientes apresentaram pelo menos uma disgenesia dentária, com predominância de alterações hipoplasiantes, principalmente representadas por hipodesenvolvimento da cúspide lingual do primeiro pré-molar inferior e opacidades de esmalte; a ocorrência de agenesias dentárias e dentes supranumerários foi semelhante à observada no grupo controle. Na análise cefalométrica, observou-se menor comprimento da base do crânio (total e da parte posterior); retrusão e redução da altura posterior da maxila; aumento do ângulo goníaco; aumento do ângulo interincisal; maior inclinação lingual dos incisivos inferiores; redução do ângulo nasolabial; e redução da profundidade nasal, comparado ao grupo controle. Com relação à síndrome G/BBB, 95,23% dos pacientes apresentaram pelo menos uma disgenesia dentária, com predominância de alterações hipoplasiantes; a freqüência de agenesias dentárias e dentes supranumerários foi significativamente maior comparada ao grupo controle. Foi observada anquiloglossia em 11 de 21 pacientes. A análise cefalométrica revelou aumento do ângulo da base do crânio; maior retrusão dos ossos nasais; encurtamento do ramo, redução do comprimento, e retrusão da mandíbula; maior discrepância maxilomandibular, com maior convexidade facial; maior inclinação lingual dos incisivos inferiores e superiores; padrão de crescimento mais vertical; nariz mais achatado, ponte nasal mais curta, maior retrusão nasal e redução da profundidade nasal, comparado ao grupo controle. Em conclusão, na avaliação de pacientes com hipótese diagnóstica das referidas síndromes, sugere-se investigar a anatomia oclusal de pré-molares inferiores no caso da síndrome velocardiofacial, e a presença de dentes supranumerários anteriores inferiores e anquiloglossia para a síndrome G/BBB. A análise cefalométrica também indicou diferenças significativas em diversas variáveis, simultaneamente servindo como parâmetro na descrição das síndromes e exigindo protocolo de tratamento diferenciado para estes pacientes. / This study investigated the prevalence of tooth abnormalities, soft tissue changes and cephalometric analysis in patients with velocardiofacial syndrome and G/BBB syndrome. The presence of tooth abnormalities was evaluated in patients older than six years; cephalometric analysis was conducted on lateral cephalograms obtained before any orthodontic intervention. The study sample for the velocardiofacial syndrome included 26 patients for analysis of tooth abnormalities and soft tissue changes, and 18 patients for cephalometric analysis. For the G/BBB syndrome, 21 patients were analyzed as to the presence of tooth abnormalities and soft tissue changes, and 23 patients for cephalometric analysis. Only white patients were included. The occurrence of tooth abnormalities and supernumerary teeth was compared to patients without any morphofunctional alterations, matched for gender and age. For cephalometric analysis, the lateral cephalograms were manually traced; tracings were digitized and the variables were measured on the software Dentofacial Planner 7.0. For this analysis, patients were also compared to individuals without malformations, matched for gender and age. For the velocardiofacial syndrome, 76.92% of patients presented at least one tooth abnormality, with predominance of hypoplastic alterations, especially represented by hypodevelopment of the lingual cusp of mandibular first premolars and enamel opacities; the occurrence of tooth agenesis and supernumerary teeth was similar to that observed in the control group. Cephalometric analysis revealed reduced length of the skull base (total and of the posterior portion); retrusion and reduction of posterior height of the maxilla; increased gonial angle; increased interincisal angle; greater lingual inclination of mandibular incisors; reduced nasolabial angle; and reduced nasal depth, compared to the control group. Concerning the G/BBB syndrome, 95.23% of patients presented at least one tooth abnormality, with predominance of hypoplastic alterations; the frequency of tooth agenesis and supernumerary teeth was significantly higher compared to the control group. Ankyloglossia was observed in 11 of 21 patients. Cephalometric analysis revealed increased cranial base angle; greater retrusion of nasal bones; shortening of mandibular ramus, reduced mandibular length, and mandibular retrusion; greater maxillomandibular discrepancy, with greater facial convexity; greater lingual inclination of maxillary and mandibular incisors; more vertical growth pattern; more flattened nose, shorter nasal bridge, greater nasal retrusion and reduced nasal depth, compared to the control group. In conclusion, during evaluation of patients with suspected diagnosis of the syndromes, investigation of the occlusal anatomy of mandibular premolars in case of velocardiofacial syndrome, and of the presence of mandibular anterior supernumerary teeth and ankyloglossia for the G/BBB syndrome are suggested. Cephalometric analysis also indicated significant differences in several variables, simultaneously serving as parameter for description of syndromes and requiring a customized treatment protocol for these patients.

<p>The two major contributing populations to the outflow tract of the heart are the secondary heart field and the cardiac neural crest. These two populations are responsible for providing the myocardium that supports the outflow tract valves, the smooth muscle that surrounds these valves and the outflow vessels themselves, and the septum that divides the primitive, single outflow tract into an aorta and pulmonary trunk. Because the morphogenesis of this region is so complex, its development is regulated by many different signaling pathways. One of these pathways is the Sonic hedgehog pathway. This thesis tests the hypothesis that Sonic hedgehog induces secondary heart field proliferation, which is necessary for normal outflow tract development. To address this hypothesis, I took advantage of small chemical antagonists and agonists to determine how too little or too much hedgehog signaling would affect the secondary heart field, both in in vitro explants and in vivo. I have determined that Sonic hedgehog signaling maintains proliferation in a subset of secondary heart field cells. This proliferation is essential for generating enough myocardium and smooth muscle and also for the cardiac neural crest to septate the outflow tract into two equal-sized vessels. Up-regulating hedgehog signaling induces proliferation, which is quickly down-regulated, showing that the embryo exhibits a great deal of plasticity. Together, these studies have shown that Sonic hedgehog promotes proliferation in a subset of the secondary heart field and that the level of proliferation must be tightly regulated in order to form a normal outflow tract.</p> / Dissertation

Made available in DSpace on 2015-07-22T20:50:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-22 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Introdução: A esquizofrenia é o transtorno mental mais grave e incapacitante entre os distúrbios psiquiátricos. Ela é uma doença complexa e com fenótipo heterogêneo. Dentre os fatores genéticos que parecem ter um papel na etiologia da esquizofrenia está a deleção 22q11.2. Objetivos: Investigar alterações cromossômicas, polimorfismos dos genes UFD1L e ZDHHC8, mutações no gene TBX1 e variações no número de cópias na esquizofrenia e na síndrome da deleção 22q11.2, e correlacionar com achados de avaliações genético-clínicas, psiquiátricas, neuropsicológicas e de neuroimagem. Métodos: Um total de 200 portadores de esquizofrenia, 200 indivíduos controles e 10 portadores do fenótipo clínico da síndrome da deleção 22q11.2, mas sem a deleção, participaram do presente estudo. Os pacientes com esquizofrenia foram estudados por citogenética clássica e Multiplex Ligation-dependent probe amplification. Os polimorfismos rs5992403 (gene UFD1L) e rs175174 (gene ZDHHC8) foram investigados em pacientes com esquizofrenia e controles por meio de PCR em tempo real com sonda TaqMan. Outros polimorfismos do gene UFD1L foram analisados, rs5746744 e rs1547931, por Restriction Fragment Length Polymorphism. Mutações no gene TBX1 foram investigadas em portadores do fenótipo clínico da síndrome da deleção 22q11.2, mas sem a deleção, por meio de sequenciamento genômico. As variações no número de cópias foram analisadas por meio da metodologia de array em pools. Os pacientes com esquizofrenia também foram avaliados por testes neuropsicológicos e por neuroimagem estrutural. Resultados: Todos os cariótipos estudados foram normais. Foi encontrada um paciente com a deleção de 1,5 megabases na região 22q11.2. Os polimorfismos rs5992403 (UFD1L) e rs175174 (ZDHHC8) foram associados com a idade de acometimento da esquizofrenia. Além disso, todos os polimorfismos investigados parecem desempenhar um papel na morfologia cerebral e em habilidades cognitvas. Nenhuma mutação foi encontrada no gene TBX1, apenas polimorfismos, em portadores do fenótipo clínico da 22q11DS. Foram encontradas três regiões amplificadas em pools de DNAs de portadores de esquizofrenia: 1p36.32, 2q37.3 e 22q11.21. Conclusões: O estudo permitiu avaliar a participação de fatores genéticos em determinadas características da esquizofrenia, propiciando um melhor entendimento sobre a etiologia e fisiopatologia dessa doença complexa. / Background: Schizophrenia is a severe, persistent, debilitating and poorly understood psychiatric disorder. It is a complex disease with heterogeneous fenotype. Among the genetic factors that might have a role in schizophrenia, it is included 22q11.2 deletion. Objectives: We aimed to investigate chromosomal abnormalities, UFD1L and ZDHHC8 polymorphisms, TBX1 mutations and copy number variations in schizophrenia and 22q11.2 deletion syndrome and associate them with clinical genetics, psychiatric, neuropsychological and neuroimaging data. Methodology: A total of 200 schizophrenia patients, 200 healthy controls and 10 patients who have the 22q11.2 syndrome phenotype but no detectable deletion were selected. Schizophrenia patients were investigated through classical karyotyping by G-banding and Multiplex Ligationdependent probe amplification. UFD1L rs5992403 and ZDHHC8 rs175174 polymorphisms were genotyped in schizophrenia patients and healthy controls by Real Time PCR using TaqMan. UFD1L rs5746744 and rs1547931 polymorphisms were genotyped by Restriction Fragment Length Polymorphism. Tbx1 mutations were investigated in patients who have the 22q11.2 syndrome phenotype but no detectable deletion by sequencing. Affymetrix 6.0 microarrays in a pool of DNA samples was used to detect copy number variations. Schizophrenia patients were evaluated by neuropsychological tests and structural neuroimaging. Results: All karyotypes were normal. One patient presented a 1.5 megabases deletion in 22q11.2 region. UFD1L rs5992403 and ZDHHC8 rs175174 polymorphisms were associated with age at onset of schizophrenia. Moreover, all studied polymorphisms may have a role in brain morphology and cognition. No mutation, only polymorphisms, in TBX1 gene was found in 22q11.2 patients. Three regions were amplified in DNA pools of schizophrenia patients: 1p36.32, 2q37.3 e 22q11.21. Conclusion: This study evaluated the role of genetic factors in some schizophrenia fenotypes, providing a better understanding of its etiology and pathophysiology. / FAPESP: 2008/56464-7 / TEDE / BV UNIFESP: Teses e dissertações