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Inherited retinal and corneal dystrophies represent a group of disorders with great genetic heterogeneity. Over 250 genes are associated with retinal diseases and 16 genes are causative of corneal dystrophies. This thesis is focused on finding the genetic causes of corneal dystrophy, Leber congenital amaurosis (LCA), Stargardt disease and retinitis pigmentosa in families from northern Sweden.  By whole exome sequencing a novel mutation, c.2816C>T, p.Thr939Ile, in Collagen Type XVII, Alpha 1 chain, COL17A1, gene was identified in several families with epithelial recurrent erosion dystrophy (ERED). We showed that the COL17A1 protein is expressed in the basement membrane of the cornea, explaining the mutation involvement in the corneal symptoms. We could link all the families in this study to a couple born in the late 1700s confirming a founder mutation in northern Sweden. Our finding highlights role of COL17A1 in ERED and suggests screening of this gene in patients with similar phenotype worldwide. Furthermore the genetic causes in several retinal degenerations were identified. In one family with two recessive disorders, LCA and Stargardt disease, a novel stop mutation, c.2557C>T, p.Gln853Stop, was detected in all LCA patients. In the Stargardt patients two intronic variants, the novel c.4773+3A>G and c.5461-10T>C, were detected in the ABCA4 gene. One individual was homozygous for the known variant c.5461-10T>C and the other one was compound heterozygote with both variants present. Both variants, c.4773+3A>G and c.5461-10T>C caused exon skipping in HEK293T cells demonstrated by in vitro splice assay, proving their pathogenicity in Stargardt disease. Finally, in recessive retinitis pigmentosa, Bothnia Dystrophy (BD), we identified a second mutation in the RLBP1 gene, c.677T>A, p.Met226Lys. Thus, BD is caused not only by common c.700C>T variant but also by homozygosity of c.677T>A or compound heterozygosity. Notably, known variant, c.40C>T, p.R14W in the CAIV gene associated with a dominant retinal dystrophy RP17 was detected in one of the compound BD heterozygote and his unaffected mother. This variant appears to be a benign variant in the population of northern Sweden. In conclusion, novel genetic causes of retinal dystrophies in northern Sweden were found demonstrating the heterogeneity and complexity of retinal diseases. Identification of the genetic defect in COL17A1 in the corneal dystrophy contributes to understanding ERED pathogenesis and encourages refinement of IC3D classification. Our results provide valuable information for future molecular testing and genetic counselling of the families.

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Orientador: Anibal Eugenio Vercesi / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-19T05:29:39Z (GMT). No. of bitstreams: 1 Figueira_TiagoRezende_D.pdf: 22742066 bytes, checksum: dd66394fba07238337b8c5a2eeb0c858 (MD5) Previous issue date: 2011 / Resumo: A analbuminemia congênita é uma doença autossômica recessiva caracterizada por níveis traços de albumina plasmática (< 1 mg/mL) e sintomas clínicos leves. Entre as comorbidades apresentadas pelos indivíduos e ratos analbuminêmicos (ratos Nagase - NAR), os distúrbios no metabolismo/transporte de lipídeos plasmáticos são as mais marcantes. A dislipidemia associada à analbuminemia é caracterizada por níveis aumentados de colesterol e triglicérides, e déficit de ácidos graxos livres (FFA). Nesta tese, são apresentados três estudos independentes sobre a analbuminemia, os quais objetivaram investigar: 1) os mecanismos da hipertrigliceridemia e do déficit de FFA plasmático do NAR; 2) o metabolismo de carboidratos no NAR; 3) as funções mitocondriais no NAR. Também é apresentado um quarto estudo (aspectos metodológicos) sobre o uso do probe safranina para avaliar o potencial elétrico transmembrana mitocondrial. Os principais resultados destes estudos foram: Estudo um: as taxas de lipogênese (596 ± 40 vs. 929 ± 124 ?mol 3H2O/g/h) e de secreção de triglicérides para o plasma (4,25 ± 1,00 vs. 7,04 ± 1,68 mg/dL/min) foram mais lentas (P ? 0,05) no NAR do que no rato controle Sprague-Dawley (SDR). As injeções de heparina ou de albumina no NAR promoveram um aumento de FFA plasmático em função do tempo. Noventa minutos após a injeção de albumina, os níveis de FFA plasmáticos nos NAR se elevaram de 0,36 ± 0,05 para 1,34 ± 0,16 mEq/L (P ? 0,05), atingindo os níveis do SDR. Estes resultados indicam que a falta de albumina plasmática inibe a lipólise intravascular e causa o déficit de FFA plasmático na analbuminemia, e que a produção hepática de triglicérides não contribui para a hipertrigliceridemia no NAR. Estudo dois: a concentração de glicose plasmática foi similar entre os NAR e os SDR alimentados ou em jejum, porém a insulinemia no estado alimentado foi maior nos NAR do que nos SDR (P ? 0,05). O NAR apresentou maior tolerância à glicose quando comparado ao SDR (P ? 0,05). Esta maior tolerância a glicose está associada à maior resposta insulinêmica à administração de glicose. Não houve diferença entre os grupos para a sensibilidade periférica a insulina. Apesar do conteúdo similar de glicogênio hepático no estado alimentado, o NAR apresentou menor conteúdo de glicogênio (40% do SDR) após 6 h de jejum. A injeção de piruvato (substrato neoglicogênico) promoveu um aumento mais rápido na glicemia do NAR em comparação ao SDR. Deste modo, os resultados indicam que o NAR apresenta metabolismo de glicose acelerado. Estudo três: a capacidade de retenção de Ca2+ pelas mitocôndrias isoladas do fígado do NAR aos três meses de idade foi ~50% daquela do SDR. Esta variável não se diferiu entre os grupos quando avaliada aos 21 dias de vida dos ratos. Foi observada uma depleção de ~20% no conteúdo de nitrosotiol e um aumento de ~30% na expressão de ciclofilina D nas mitocôndrias de fígado do NAR. Nenhuma das variáveis relacionadas ao estado redox mitocondrial diferiu entre NAR e SDR, tais como: o conteúdo de tióis reduzidos, de glutationa total, a taxa de liberação de H2O2, e o estado reduzido de NAD(P)H. Com isso, conclui-se que a maior expressão de ciclofilina D, um componente importante no processo de transição de permeabilidade mitocondrial, e o menor conteúdo de nitrosotiol nas mitocôndrias dos NAR podem explicar a sua menor capacidade de retenção de Ca2+ / Abstract: Congenital analbuminemia is a rare autosomal recessive disorder characterized by a trace level of albumin in blood plasma and mild clinical symptoms. Analbuminemic patients and rats (Nagase analbuminemic rats - NAR) present associated abnormalities, among which the disturbances in plasma lipid metabolism and transport are hallmarks. The dyslipidemia associated with analbuminemia comprises a unique plasma lipid profile (i.e. high cholesterol and triglycerides, but a severe free-fatty acids deficiency). Three independent works on analbuminemia are presented in this PhD thesis, whose aims were: 1) to investigate the mechanisms of NAR hypertriglyceridemia and plasma free-fatty acids deficiency; 2) to study carbohydrate metabolism in NAR; 3) to evaluate mitochondrial (dys)function in NAR. Also, a methodological study about the use of the dye safranine as a fluorescent probe for the assessment of mitochondrial transmembrane electrical potential is presented in this thesis. The main results from these studies were: Study one: lipogenesis (596 ± 40 vs. 929 ± 124 ?mol 3H2O/g/h) and triglyceride secretion rates (4.25 ± 1.00 vs. 7.04 ± 1.68 mg/dL/min) were slower (P ? 0.05) in fasted NAR than in control Sprague-Dawley rats (SDR). The injection of either heparin or albumin elicited an increase in NAR plasma FFA levels over time. FFA levels reached control levels 90 min after the albumin administration into NAR, increasing from 0.36 ± 0.05 to 1.34 ± 0.16 mEq/L (P ? 0.05). These results indicate that the lack of plasma albumin inhibits intravascular lipolysis and causes the FFA deficit observed in NAR. Moreover, hepatic triglyceride output seems not to contribute to NAR hypertriglyceridemia. Study two: plasma glucose levels were similar between fed and fasted NAR and SDR, but fed insulinemia was higher in NAR than in SDR (P ? 0.05). NAR displayed increased glucose tolerance compared to SDR (P ? 0.05). This enhanced glucose tolerance was associated with higher insulinemia after the glucose load, and with similar insulin sensitivity between the groups. Despite similar liver glycogen content in fully fed condition, NAR had lower glycogen content (40% of control) after 6-h fasting. The injection of pyruvate (gluconeogenic substrate) elicited a faster rise in glycemia of NAR than in SDR. Therefore, NAR display enhanced glucose metabolism. Study three: the Ca2+ retention capacity of the liver mitochondria isolated from 3-month-old NAR was about 50% that of the control. Interestingly, the assessment of this variable in 21-day-old NAR and SDR indicated that the mitochondrial Ca2+ retention capacity was preserved at this age. A 20% decrease in mitochondrial nitrosothiol content and a 30% increase in cyclophilin D expression were observed in NAR liver mitochondria. None of the variables related to mitochondrial redox state differed between the controls and NAR, i.e., namely the contents of reduced mitochondrial membrane protein thiol groups and total glutathione, H2O2 release rate, and NAD(P)H reduced state. We conclude that the higher expression of cyclophilin D, a major component in the mitochondrial permeability transition process, and decreased nitrosothiol content in NAR mitochondria may underlie their lower Ca2+ retention capacity / Doutorado / Biologia Estrutural, Celular, Molecular e do Desenvolvimento / Doutor em Ciências

Chondrodysplasia of Texel sheep is a newly described recessively inherited disorder distinct from other chondrodysplasias described in sheep. Phenotypically normal at birth, affected lambs develop microscopic lesions as early as 9 days of age, and usually demonstrate gross deformities and markedly reduced rates of bone growth by 2 to 3 weeks. Individual bone growth rates are most severely affected in the proximal bones of the forelimbs. Chondrodysplastic lambs typically have short stature, angular limb deformities, a barrel-shaped chest and a wide-based stance. Gross lesions include tracheal narrowing and contortion, enlarged costochondral junctions, and erosion of articular cartilage in major limb joints. Microscopic lesions are confined to hyaline cartilage, and are characterised by degeneration of the interterritorial matrix and dense perichondrocytic rings consisting predominantly of type VI collagen. These lesions are identical in appearance to those in achondrogenesis 1b and diastrophic dysplasia, two diseases caused by defects of the diastrophic dysplasia sulphate transporter (DTDST) in human beings. An investigation to measure the uptake of radiolabelled sulphate by dermal fibroblasts in vitro did not provide evidence of a defect in the DTDST in chondrodysplastic Texel sheep. A linkage disequilibrium study of ovine chromosomes 1, 5, 6, 13 and 22 using microsatellite DNA markers was unable to identify evidence of a mutation causing this form of chondrodysplasia. Capillary electrophoresis of unsaturated chondroitin sulphate disaccharides demonstrated a relative reduction in the ratio of chondroitin 4-sulphate to chondroitin 6-sulphate in affected animals of all ages. This biochemical feature enables the potential determination of the phenotype of newborn lambs prior to the emergence of gross or microscopic lesions. The pathology of the disease, combined with the findings of the genetic, biochemical and in vitro studies, suggest that a mutation may be present in the CHST11 gene. This gene is a good candidate for future studies aimed at discovering the genetic defect in chondrodysplasia of Texel sheep and developing a test to identify heterozygous animals.

Chondrodysplasia of Texel sheep is a newly described recessively inherited disorder distinct from other chondrodysplasias described in sheep. Phenotypically normal at birth, affected lambs develop microscopic lesions as early as 9 days of age, and usually demonstrate gross deformities and markedly reduced rates of bone growth by 2 to 3 weeks. Individual bone growth rates are most severely affected in the proximal bones of the forelimbs. Chondrodysplastic lambs typically have short stature, angular limb deformities, a barrel-shaped chest and a wide-based stance. Gross lesions include tracheal narrowing and contortion, enlarged costochondral junctions, and erosion of articular cartilage in major limb joints. Microscopic lesions are confined to hyaline cartilage, and are characterised by degeneration of the interterritorial matrix and dense perichondrocytic rings consisting predominantly of type VI collagen. These lesions are identical in appearance to those in achondrogenesis 1b and diastrophic dysplasia, two diseases caused by defects of the diastrophic dysplasia sulphate transporter (DTDST) in human beings. An investigation to measure the uptake of radiolabelled sulphate by dermal fibroblasts in vitro did not provide evidence of a defect in the DTDST in chondrodysplastic Texel sheep. A linkage disequilibrium study of ovine chromosomes 1, 5, 6, 13 and 22 using microsatellite DNA markers was unable to identify evidence of a mutation causing this form of chondrodysplasia. Capillary electrophoresis of unsaturated chondroitin sulphate disaccharides demonstrated a relative reduction in the ratio of chondroitin 4-sulphate to chondroitin 6-sulphate in affected animals of all ages. This biochemical feature enables the potential determination of the phenotype of newborn lambs prior to the emergence of gross or microscopic lesions. The pathology of the disease, combined with the findings of the genetic, biochemical and in vitro studies, suggest that a mutation may be present in the CHST11 gene. This gene is a good candidate for future studies aimed at discovering the genetic defect in chondrodysplasia of Texel sheep and developing a test to identify heterozygous animals.

Chondrodysplasia of Texel sheep is a newly described recessively inherited disorder distinct from other chondrodysplasias described in sheep. Phenotypically normal at birth, affected lambs develop microscopic lesions as early as 9 days of age, and usually demonstrate gross deformities and markedly reduced rates of bone growth by 2 to 3 weeks. Individual bone growth rates are most severely affected in the proximal bones of the forelimbs. Chondrodysplastic lambs typically have short stature, angular limb deformities, a barrel-shaped chest and a wide-based stance. Gross lesions include tracheal narrowing and contortion, enlarged costochondral junctions, and erosion of articular cartilage in major limb joints. Microscopic lesions are confined to hyaline cartilage, and are characterised by degeneration of the interterritorial matrix and dense perichondrocytic rings consisting predominantly of type VI collagen. These lesions are identical in appearance to those in achondrogenesis 1b and diastrophic dysplasia, two diseases caused by defects of the diastrophic dysplasia sulphate transporter (DTDST) in human beings. An investigation to measure the uptake of radiolabelled sulphate by dermal fibroblasts in vitro did not provide evidence of a defect in the DTDST in chondrodysplastic Texel sheep. A linkage disequilibrium study of ovine chromosomes 1, 5, 6, 13 and 22 using microsatellite DNA markers was unable to identify evidence of a mutation causing this form of chondrodysplasia. Capillary electrophoresis of unsaturated chondroitin sulphate disaccharides demonstrated a relative reduction in the ratio of chondroitin 4-sulphate to chondroitin 6-sulphate in affected animals of all ages. This biochemical feature enables the potential determination of the phenotype of newborn lambs prior to the emergence of gross or microscopic lesions. The pathology of the disease, combined with the findings of the genetic, biochemical and in vitro studies, suggest that a mutation may be present in the CHST11 gene. This gene is a good candidate for future studies aimed at discovering the genetic defect in chondrodysplasia of Texel sheep and developing a test to identify heterozygous animals.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / In one research, cases of congenital lymphedema were observed affecting 17 Red Angus calves and their crosses from two farms in the central region of the state of Rio Grande do Sul, Brazil. Affected calves presented variable degrees of subcutaneous edema at birth, involving mainly the hind limbs, but also other body regions. The injection of methylene blue dye in a 5% solution into the interdigital space of the hind limbs of three affected calves and one normal control indicated an interruption of the lymph flow in the affected calves; this suggests a failure of the distal peripheral lymphatics to connect with the central trunks. At necropsy of three affected calves, subcutaneous edema was variably observed in the hind limbs, prepuce and ventral abdomen. Edema of body cavities was not observed. In two cases there was hipoplasia of the popliteal lymph nodes associated to dilatation of lymphatic vessels. DNA tests demonstrated that all affected calves were born from cows sired by the same bull suggesting an inherited basis for the disease. Furthermore unrelated cows of different breeds sired by Bull 1 delivered affected calves which suggest that condition is an autosomic dominant trait. Considering the large numbers of cows sired by Bull 1 relative few calves were affected; this could be explained by a low penetrance of the trait. In another research, cases of congenital defects (CDs) in cattle diagnosed at the Laboratory of Veterinary Pathology of the Federal University of Santa Maria from 1964 to 2010 were reviewed. During the studied period, tissues collected from the necropsy of 7,132 cattle were examined and 31 calves (0.4%) with CDs were found. These CDs were classified into 34 different types and ascribed to the body system primarily affected. The results of this survey indicate that the majority o CDs in cattle in the central Rio Grande do Sul are sporadic; nevertheless their continued study is important for determining the etiology and control. / Em uma pesquisa, casos de linfedema congênito foram observados acometendo 17 bezerros cruza Red Angus na região Central do Rio Grande do Sul. Os bezerros afetados apresentavam graus variáveis de edema subcutâneo ao nascimento, envolvendo principalmente os membros pélvicos, mas também outras regiões do corpo. A injeção de solução a 5% de azul de metileno no espaço interdigital dos membros pélvicos de três bezerros afetados e um controle, indicaram uma interrupção no fluxo da linfa, sugerindo uma falha dos linfáticos periféricos distais em conectar os troncos centrais. Na necropsia de três bezerros afetados, edema subcutâneo foi observado de modo variável nos membros pélvicos, prepúcio e abdômen ventral. Não foi observado edema nas cavidades orgânicas. Em dois casos, observou-se hipoplasia dos linfonodos poplíteos associadas à dilatação dos vasos linfáticos. Testes de DNA demonstraram que todos os bezerros afetados nasceram de vacas inseminadas pelo mesmo touro (Touro 1), sugerindo uma base genética para a doença. Além disso, vacas não relacionadas e de outras raças cobertas pelo Touro 1 pariram bezerros afetados indicando uma condição autossômica dominante. Considerando o grande número de vacas cobertas pelo Touro 1, relativamente poucos bezerros foram afetados; isso pode ser explicado por uma condição hereditária de baixa penetrância. Em outra pesquisa, foram revisados casos de defeitos congênitos (DCs) diagnosticados em bovinos no Laboratório de Patologia da Universidade Federal de Santa Maria entre 1964-2010. Durante o período estudado, foram examinados materiais provenientes da necropsia de 7.132 bovinos e foram encontrados 31 bezerros (0,4%) com DCs, os quais foram classificados em 34 tipos e alocados nos sistemas orgânicos primariamente afetados. Os resultados indicam que a maioria dos DCs em bovinos na Região Central do Rio Grande do Sul é esporádica. No entanto, seu estudo continuado é importante para o estabelecimento de sua etiologia e controle.