<p><strong>Abstract</strong></p> <p>Sandhoff disease (SD) is a monogenic lysosomal storage disorder caused by a lack of a functional β-subunit of the beta-hexosaminidase A and B enzymes. The clinical phenotype of <em>Hexb</em>^-/-mouse model recapitulates the symptoms and signs of Tay-Sachs and Sandhoff diseases in human. To gain insight into the neuropathology of Sandhoff disease, we defined the role of TNFα in the development and progression of Sandhoff disease pathology in mice, by generating a <em>Hexb^-/-Tnf</em><em>a</em><em>^-/-</em> double knock-out mouse. Behavioural testing and immunostaining data revealed the neurodegenerative role of TNFα in disease pathology. Double knock-out mice showed ameliorated clinical course, with prolonged life span. TNFα-deficient Sandhoff mice also demonstrate decreased levels of astrogliosis, and reduced neuronal cell death. Deletion of <em>Tnfα</em> in Sandhoff mice inhibited JAK2/STAT3 pathway, implicating its role in glia cell activation. This result points to TNFa as a potential therapeutic target to attenuate neuro-pathogenesis.</p> <p>To investigate whether blood-derived or CNS-derived TNFα has the major impact on neurological function, we transplanted <em>Hexb^-/-Tnfα^+/+</em> with bone marrow from either <em>Hexb^-/-Tnfα^-/-</em>or <em>Hexb^-/-Tnf</em><em>a</em><em>^+/+</em> mice donors. Neurological tests shows a significant clinical improvement for Hexb<em>^-/-Tnfα^-/-</em> compared to <em>Hexb^-/-Tnf</em><em>a</em><em>^+/+</em> recipient, regardless the genotype of donor cells. These findings highlight the importance of resident-derived TNFα during the robust neurodegenerative consequences in Sandhoff disease. To understand of the role of microRNAs in Sandhoff pathology, we investigated the miRNA profile in Sandhoff brains. A pattern of dys-regulated microRNAs was evident in Sandhoff CNS. Microarray identified miR-210 and miR-96 dys-regulated pattern in the CNS of Sandhoff mice. Strikingly, neuronal pentraxin, a putative target gene for miR-210, was induced in Sandhoff brains.</p> <p>Taken together, this work establishes the proinflammatory role of TNFα in Sandhoff pathology, leading to massive neuro-apoptosis. Importantly, our studies propose that neuronal pentraxin as a novel target gene for microRNA-210 in Sandhoff brain samples, providing a potential modulator of neurodegeneration.</p> / Doctor of Philosophy (PhD)

Intrdodução: As terapias com anticonvulsivantes de anel aromático (ACA) são freqüentemente associadas a reações adversas. No entanto, reações de hipersensibilidade (RH) não-imediatas (tardias) a estes fármacos são raras, imprevisíveis e geralmente relacionadas à alta morbidade e mortalidade. Foi demonstrado que estas RH aos ACA estão fortemente associadas ao Antígenio de Leucócitos Humanos (HLA)-B*1502 em pacientes chineses e ao HLA-A*3101 em caucasianos. Polimorfismos de genes do metabolismo do Citocromo P450 (CYP)2C9 foram mais associados a estas reações em pacientes orientais. Objetivo: Nosso objetivo é analisar a associação das reações de hipersensibilidade a anticonvulsivantes de anel aromático com os polimorfismos descritos e de interesse, bem como realizar a tipificação de HLA em uma população de São Paulo, Brasil. Métodos: Estudo tipo caso-controle com genotipagem dos polimorfismos de interesse por reação em cadeia da polimerase (PCR) em tempo real e tificação de HLA A, B, C, DRB, DQA, DQB por PCR seguido de deteção utilizando método LuminexR. A avaliação fenotípica se baseou em sistemas de escores padronizados, utilizando um questionário adaptado da ENDA (Rede Européia de Alergia a Medicamentos), em registros médicos e no acompanhamento clínico. O teste de contato com o medicamento suspeito foi realizado de acordo com as recomendações da ENDA, nos pacientes que apresentaram reação. Resultados: Foram estudados 506 pacientes, 65% do gênero feminino e a idade média foi de 43,6 anos. Oitenta por cento era de etnia mista. Polimorfismos de HLA-A*3101, HLA-B*1502, CYP2C9, CYP2C19 e CYP3A5 foram analisados de 55 indivíduos com reações de hipersensibilidade (RH) a antiepilépticos, de 85 tolerantes e de 366 controles sadios. Dos 55 casos foram validados como RH, 32 apresentaram Reação a Drogas com eosinofilia e sintomas sistêmicos (DRESS), 12 Síndrome de Stevens-Johnson (SSJ) e 11 exantema maculo-papular. De todos os 46 testes de contato com medicamento, 29 (63%) foram positivos, tanto em SSJ como em DRESS. Houve associação significativa entre polimorfismo de HLA-A*1502 e casos. Nenhum de nossos grupos de estudo apresentou associação positiva com polimorfismos de HLAA* 3101. Verificamos uma forte associação entre a atividade normal do CYP3A5 e indivíduos tolerantes quando comparado com casos (p = 0,0002, OR = 4,8). A tipificação de HLA demonstrou associação significante de HLA-A*31, HLA-A*74, HLA-B*35 e HLA-B*53 com reações graves aos ACA e de HLA-B*44 e HLA-C*03 com indivíduos tolerantes. Conclusão: Estes resultados sugere fortemente a existência de fatores genéticos de risco e/ou de proteção a RH a ACA em indivíduos brasileiros, mas não devem ser considerados de forma isolada. Assim, a relevância deste estudo extrapola o objetivo de estudo caso-controle e sugere um modelo como forma de prevenção primária às RH aos ACA. / Background: Antiepileptics with aromatic ring (AAR) therapies are frequently associated with adverse reactions. Nevertheless non-immediate (late) hypersensitivity reactions (HR) to these drugs are rare, unpredictable and usually related with high morbidity and mortality. A strong pharmacogenetic association has been reported in Chinese patients with these HR and Human Leukocyte Antigen (HLA)-B*1502 and with HLA- A*3101 in caucasians. Polymorphism of genes of P450 Cytocrome (CYP)2C9 has been related to these reactions in patients of oriental origin. Objective: Our aim is to analyze the association between hypersensitivity reactions due to AAR and the described polymorphisms, as well as perform the typification of HLA in a population of São Paulo, Brazil. Methods: Case-control study genotyping the polymorphisms of interest by polymerase chain reaction (PCR) real time and typifying HLA A, B, C, DRB, DQA, DQB by PCR followed by LuminexR .The phenotype evaluation was based on standardized scoring systems using an adapted ENDA (European Network of Drug Allergy) questionnaire, medical records and on the clinical follow-up in our Allergy Clinic. The patch test with the culprit drug was performed in patients who experienced HR according to the ENDA recommendations. Results: We studied 506 subjects, 65% female and mean age was 43,6 years. Eighty percent had mixed ethnicity. Polymorphisms of HLA-B*1502, HLA- A*3101, CYP2C9, CYP2C19 e CYP3A5 were studied in 55 subjects with antiepileptics HR, 85 tolerants, and 366 control subjects. Of 55 cases were validated as AHR, 32 presented Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), 12 Stevens-Johnson Syndrome (SJS) and 11 maculopapular exanthema. Of all 46 drug patch tests, 29 (63%) were positive, in both SJS and DRESS. A significant association between polymorphism of HLA-A*1502 and cases was found. None of our study groups presented positive association with HLA-A*3101 polymorphisms. We found a strong association between the normal activity of CYP3A5 and tolerants subjects when compared to HR (p=0.0002, OR=4.8). The HLA typification showed a significant association between HLA-A*31, HLA-A*74, HLAB* 35 e HLA-B*53 and severe AAR reactions and HLA-B*44 and HLA-C*03 in tolerants subjects. Conclusion: These results strongly suggests the existence of genetic risk and/or protective factors to the development of HR to AAR AAR in Brazilian subjects, but it should not be considered in a isolated manner. So, the relevance of this study extrapolates the aim of a case-control study and suggests a system of primary prevention to HR due to AAR

Genomic instability, in the form of gene mutations, insertions/deletions, and gene amplifications, is one of the hallmarks in many types of cancers and other inheritable genetic disorders. Trinucleotide repeat (TNR) disorders, such as Huntington’s disease (HD) and Myotonic dystrophy (DM) can be inherited and repeats may be extended through subsequent generations. However, it is not clear how the CAG repeats expand through generations in HD. Two possible repeat expansion mechanisms include: 1) polymerase mediated repeat extension; 2) persistent TNR hairpin structure formation persisting in the genome resulting in expansion after subsequent cell division. Recent in vitro studies suggested that a family A translesion polymerase, polymerase θ (Polθ), was able to synthesize DNA larger than the template DNA. Clinical and in vivo studies showed either overexpression or knock down of Polθ caused poor survival in breast cancer patients and genomic instability. However, the role of Polθ in TNR expansion remains unelucidated. Therefore, we hypothesize that Polθ can directly cause TNR expansion during DNA synthesis. The investigation of the functional properties of Polθ during DNA replication and TNR synthesis will provide insight for the mechanism of TNR expansion through generations.

Intrdodução: As terapias com anticonvulsivantes de anel aromático (ACA) são freqüentemente associadas a reações adversas. No entanto, reações de hipersensibilidade (RH) não-imediatas (tardias) a estes fármacos são raras, imprevisíveis e geralmente relacionadas à alta morbidade e mortalidade. Foi demonstrado que estas RH aos ACA estão fortemente associadas ao Antígenio de Leucócitos Humanos (HLA)-B*1502 em pacientes chineses e ao HLA-A*3101 em caucasianos. Polimorfismos de genes do metabolismo do Citocromo P450 (CYP)2C9 foram mais associados a estas reações em pacientes orientais. Objetivo: Nosso objetivo é analisar a associação das reações de hipersensibilidade a anticonvulsivantes de anel aromático com os polimorfismos descritos e de interesse, bem como realizar a tipificação de HLA em uma população de São Paulo, Brasil. Métodos: Estudo tipo caso-controle com genotipagem dos polimorfismos de interesse por reação em cadeia da polimerase (PCR) em tempo real e tificação de HLA A, B, C, DRB, DQA, DQB por PCR seguido de deteção utilizando método LuminexR. A avaliação fenotípica se baseou em sistemas de escores padronizados, utilizando um questionário adaptado da ENDA (Rede Européia de Alergia a Medicamentos), em registros médicos e no acompanhamento clínico. O teste de contato com o medicamento suspeito foi realizado de acordo com as recomendações da ENDA, nos pacientes que apresentaram reação. Resultados: Foram estudados 506 pacientes, 65% do gênero feminino e a idade média foi de 43,6 anos. Oitenta por cento era de etnia mista. Polimorfismos de HLA-A*3101, HLA-B*1502, CYP2C9, CYP2C19 e CYP3A5 foram analisados de 55 indivíduos com reações de hipersensibilidade (RH) a antiepilépticos, de 85 tolerantes e de 366 controles sadios. Dos 55 casos foram validados como RH, 32 apresentaram Reação a Drogas com eosinofilia e sintomas sistêmicos (DRESS), 12 Síndrome de Stevens-Johnson (SSJ) e 11 exantema maculo-papular. De todos os 46 testes de contato com medicamento, 29 (63%) foram positivos, tanto em SSJ como em DRESS. Houve associação significativa entre polimorfismo de HLA-A*1502 e casos. Nenhum de nossos grupos de estudo apresentou associação positiva com polimorfismos de HLAA* 3101. Verificamos uma forte associação entre a atividade normal do CYP3A5 e indivíduos tolerantes quando comparado com casos (p = 0,0002, OR = 4,8). A tipificação de HLA demonstrou associação significante de HLA-A*31, HLA-A*74, HLA-B*35 e HLA-B*53 com reações graves aos ACA e de HLA-B*44 e HLA-C*03 com indivíduos tolerantes. Conclusão: Estes resultados sugere fortemente a existência de fatores genéticos de risco e/ou de proteção a RH a ACA em indivíduos brasileiros, mas não devem ser considerados de forma isolada. Assim, a relevância deste estudo extrapola o objetivo de estudo caso-controle e sugere um modelo como forma de prevenção primária às RH aos ACA. / Background: Antiepileptics with aromatic ring (AAR) therapies are frequently associated with adverse reactions. Nevertheless non-immediate (late) hypersensitivity reactions (HR) to these drugs are rare, unpredictable and usually related with high morbidity and mortality. A strong pharmacogenetic association has been reported in Chinese patients with these HR and Human Leukocyte Antigen (HLA)-B*1502 and with HLA- A*3101 in caucasians. Polymorphism of genes of P450 Cytocrome (CYP)2C9 has been related to these reactions in patients of oriental origin. Objective: Our aim is to analyze the association between hypersensitivity reactions due to AAR and the described polymorphisms, as well as perform the typification of HLA in a population of São Paulo, Brazil. Methods: Case-control study genotyping the polymorphisms of interest by polymerase chain reaction (PCR) real time and typifying HLA A, B, C, DRB, DQA, DQB by PCR followed by LuminexR .The phenotype evaluation was based on standardized scoring systems using an adapted ENDA (European Network of Drug Allergy) questionnaire, medical records and on the clinical follow-up in our Allergy Clinic. The patch test with the culprit drug was performed in patients who experienced HR according to the ENDA recommendations. Results: We studied 506 subjects, 65% female and mean age was 43,6 years. Eighty percent had mixed ethnicity. Polymorphisms of HLA-B*1502, HLA- A*3101, CYP2C9, CYP2C19 e CYP3A5 were studied in 55 subjects with antiepileptics HR, 85 tolerants, and 366 control subjects. Of 55 cases were validated as AHR, 32 presented Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS), 12 Stevens-Johnson Syndrome (SJS) and 11 maculopapular exanthema. Of all 46 drug patch tests, 29 (63%) were positive, in both SJS and DRESS. A significant association between polymorphism of HLA-A*1502 and cases was found. None of our study groups presented positive association with HLA-A*3101 polymorphisms. We found a strong association between the normal activity of CYP3A5 and tolerants subjects when compared to HR (p=0.0002, OR=4.8). The HLA typification showed a significant association between HLA-A*31, HLA-A*74, HLAB* 35 e HLA-B*53 and severe AAR reactions and HLA-B*44 and HLA-C*03 in tolerants subjects. Conclusion: These results strongly suggests the existence of genetic risk and/or protective factors to the development of HR to AAR AAR in Brazilian subjects, but it should not be considered in a isolated manner. So, the relevance of this study extrapolates the aim of a case-control study and suggests a system of primary prevention to HR due to AAR

Genome-wide association studies have greatly improved our understanding of the contribution of common variants to the genetic architecture of complex traits. However, two major limitations have been highlighted. First, common variant associations typically do not identify the causal variant and/or the gene that it is exerting its effect on to influence a trait. Second, common variant associations usually consist of variants with small effects. As a consequence, it is more challenging to harness their translational impact. Association studies of rare variants and complex traits may be able to help address these limitations. Empirical population genetic data shows that deleterious variants are rare. More specifically, there is a very strong depletion of common protein truncating variants (PTVs, commonly referred to as loss-of-function variants) in the genome, a group of variants that have been shown to have large effect on gene function, are enriched for severe disease-causing mutations, but in other instances may actually be protective against disease. This thesis is divided into three parts dedicated to the study of protein truncating variants, their medical relevance, and their functional consequences. First, I present statistical, bioinformatic, and computational methods developed for the study of protein truncating variants and their association to complex traits, and their functional consequences. Second, I present application of the methods to a number of case-control and quantitative trait studies discovering new variants and genes associated to breast and ovarian cancer, type 1 diabetes, lipids, and metabolic traits measured with NMR spectroscopy. Third, I present work on improving annotation of protein truncating variants by studying their functional consequences. Taken together, these results highlight the utility of interrogating protein truncating variants in medical and functional genomic studies.

No description available.