Thèse (M.Sc.)--Université Laval, 2004. / Bibliogr.: f. 86-100. Publié aussi en version électronique.

Le glaucome primaire à angle ouvert (GPAO), caractérisé par une dégénérescence du nerf optique, est une maladie complexe et génétiquement hétérogène. La grande famille canadienne française CA, où la mutation myociline K423E cause le GPAO selon un mode autosomique dominant, présente une très grande variabilité de l'âge au diagnostic (AAD) pour la maladie. Pour déterminer si WDR36, le troisième gène identifié pour le GPAO, est aussi un gène modificateur altérant la sévérité du glaucome, nous avons fait une étude de corrélations génotype-phénotype chez 142 porteurs hétérozygotes de myociline K423E. Nous avons comparé l'AAD des doubles-porteurs de myociline K423E et de variations non-synonymes dans WDR36 avec la médiane de l'AAD de leurs proches parents porteurs seulement de myociline K423E. La majorité des dix-huit porteurs WDR36 satisfaisant les critères d'analyse avait un AAD plus jeune que la médiane de leurs proches parents. Quatre des cinq porteurs WDR36 D658G furent diagnostiqués de 9 à 15 ans plus jeune que leur médiane. En conclusion, notre étude suggère que WDR36 pourrait être un gène modificateur du glaucome puisque certains variants diminuent l' AAD lorsque le GPAO est causé par une mutation myociline.

Orientador: Mônica Barbosa de Melo / Dissertação (mestrado - Universidade Estadual de Campinas, Intituo de Biologia / Made available in DSpace on 2018-08-20T18:09:19Z (GMT). No. of bitstreams: 1 Braghini_CarolinaAyumi_M.pdf: 2316733 bytes, checksum: 1031a8585bbf2541b2b39db621d9f45d (MD5) Previous issue date: 2012 / Resumo: O glaucoma compreende um grupo heterogêneo de neuropatias ópticas, caracterizadas pela escavação do disco óptico e perda progressiva do campo visual, representando uma das maiores causas mundiais de perda irreversível da visão. Em 1997, o gene Myocilin (MYOC) foi descoberto, e mutações neste gene foram envolvidas no desenvolvimento do glaucoma primário de ângulo aberto (GPAA) e do GPAA do tipo juvenil (GPAA-J). No Brasil, 35,7% e 3,85% dos pacientes com GPAA-J e GPAA, respectivamente, são portadores de mutações no gene MYOC. O gene citocromo P450, família 1, subfamília B, polipeptídeo 1 (CYP1B1), primeiramente associado ao glaucoma congênito primário, tem sido apontado como modulador do fenótipo do GPAA na presença de alterações no gene MYOC. Recentemente, observaram-se mutações no gene CYP1B1 associadas ao GPAA e GPAA-J, independentemente da presença de alterações estruturais no gene MYOC, em diferentes populações. Este projeto se propôs a avaliar mutações nos genes MYOC e CYP1B1, utilizando técnicas de PCR e sequenciamento direto, em 100 indivíduos pertencentes a famílias com GPAA ou GPAA-J e 43 pacientes não relacionados portadores de GPAA-J, bem como avaliar a possível modulação do gene CYP1B1 no fenótipo da doença. Uma nova mutação no gene MYOC, c.1187_1188insCCCAGA, foi identificada segregando com a doença em três gerações de uma família. De acordo com análises in silico, esta mutação pode alterar os contatos internos da proteína, além de comprometer um sítio de fosforilação de caseína quinase II. Nas demais três famílias foi detectada a mutação C433R, já descrita anteriormente. Como os membros das famílias apresentavam fenótipos bastante variados, foi realizada a análise da possível modulação do fenótipo da doença pelo gene CYP1B1. Contudo, as análises mostraram a não associação de variantes deste gene na modulação do fenótipo do glaucoma nestas famílias. Nos casos não relacionados de GPAA-J, foram observadas as mutações P370L, Q368X e C433R. Nenhuma mutação no gene CYP1B1 foi identificada nestes casos, mas somente polimorfismos: R48G, A119S, V243V, V432L, A443G, D449D e N453S. De acordo com este e outros estudos, é possível concluir que mutações no gene MYOC tem papel importante no desenvolvimento do GPAA e GPAA-J, sendo a mutação C433R a mais frequente na população brasileira. Além disso, o gene CYP1B1 parece ter menor contribuição no desenvolvimento destes tipos de glaucoma em nossa população / Abstract: Glaucoma comprises a group of heterogeneous optic neuropathies characterized by excavation of the optic disc and progressive loss of visual field, representing a major global cause of irreversible blindness. In 1997, the Myocilin gene (MYOC) was discovered, and mutations in this gene were involved in the development of primary open-angle glaucoma (POAG) and juvenile-onset of POAG (JOAG). In Brazil, 35.7% and 3.85% of patients with POAG and JOAG, respectively, are carriers of mutations in the MYOC gene. The gene cytochrome P450, family 1, subfamily B, polypeptide 1 (CYP1B1), primarily associated with primary congenital glaucoma, has been related to phenotypic modulation of POAG in the presence of MYOC gene mutations. Recently, mutations in the CYP1B1 gene associated with POAG and JOAG were observed, regardless the presence of structural alterations in the MYOC gene in different populations. This project proposed to evaluate mutations in the MYOC and CYP1B1 genes using PCR and direct sequencing, in 100 individuals belonging to families with JOAG or POAG and 43 unrelated JOAG patients, and assess the possible role of the CYP1B1 gene in modulating the disease phenotype. A novel mutation in the MYOC gene, c.1187_1188insCCCAGA, was detected, segregating with the disease in three generations of one family. According to in silico analysis, this mutation can change the internal contacts of the protein, and has altered a phosphorylation site of casein kinase II. In the other three families the C433R mutation was detected, as described earlier. As family members presented with very different phenotypes, the CYP1B1 gene was evaluated as a possible modulator of the disease. However, the analysis showed no association of variants in CYP1B1 gene in modulating the glaucoma phenotype in these families. In unrelated cases of JOAG, the mutations P370L, Q368X and C433R were detected. No mutation in the CYP1B1 gene was observed in these cases, but only polymorphisms: R48G, A119S, V243V, V432L, A443G, D449D, and N453S. According to the present and other studies, we conclude that mutations in the MYOC gene play an important role in the development of POAG and JOAG, and the C433R mutation is the most frequent MYOC alteration in the Brazilian population. Furthermore, the CYP1B1 gene seems to have less contribution to the development of these types of glaucoma in our population / Mestrado / Genetica Animal e Evolução / Mestre em Genética e Biologia Molecular

<p>Glaucoma is one of the leading causes of visual impairment in the world. In glaucoma, the patient’s peripheral vision is lost due to progressive and irreversible deterioration of the retinal ganglion cells and atrophy of the optic nerve. The effect on the visual field is gradual and painless, and the progression so slow, that the patient may not notice until a substantial part of the visual field is lost. If left untreated, glaucoma can lead to blindness.</p><p>In this thesis, genes associated to glaucoma have been analysed in Swedish patients with primary open angle and exfoliative glaucoma. The genes studied were <i>MYOC</i>, <i>oculomedin,</i> <i>GSTM1</i> and <i>OPTN</i>.</p><p>The coding sequence of <i>MYOC</i> was analysed and mutations were found in 1% of the primary open angle glaucoma patients. Additionally, a predisposing variant was found in 1% of the patients as well as in 0.5% of the controls. No disease-associated variation was found in the exfoliative glaucoma cases. Mutations were also found in two families affected by glaucoma. The coding sequence of <i>oculomedin</i> was analysed, but none of the variants found were classified as disease causing in either patient group. <i>GSTM1</i> was analysed for its presence in the patients. No association could be found for either hetero- or homozygous deletions. The coding sequence and haplotype distribution of <i>OPTN</i> was analysed. None of the variants found were classified as disease causing and none of the haplotypes were associated to the disease in either patient group.</p><p>There are just a few per cent of the Swedish primary open angle glaucoma patients with genetic variation associated to disease, in the genes analysed in this study. No association to exfoliative glaucoma was found. This indicates heterogeneity in the genetics of glaucoma when different subtypes and different populations are compared. Likely, there are genes still to be identified.</p>

Glaucoma is one of the leading causes of visual impairment in the world. In glaucoma, the patient’s peripheral vision is lost due to progressive and irreversible deterioration of the retinal ganglion cells and atrophy of the optic nerve. The effect on the visual field is gradual and painless, and the progression so slow, that the patient may not notice until a substantial part of the visual field is lost. If left untreated, glaucoma can lead to blindness. In this thesis, genes associated to glaucoma have been analysed in Swedish patients with primary open angle and exfoliative glaucoma. The genes studied were MYOC, oculomedin, GSTM1 and OPTN. The coding sequence of MYOC was analysed and mutations were found in 1% of the primary open angle glaucoma patients. Additionally, a predisposing variant was found in 1% of the patients as well as in 0.5% of the controls. No disease-associated variation was found in the exfoliative glaucoma cases. Mutations were also found in two families affected by glaucoma. The coding sequence of oculomedin was analysed, but none of the variants found were classified as disease causing in either patient group. GSTM1 was analysed for its presence in the patients. No association could be found for either hetero- or homozygous deletions. The coding sequence and haplotype distribution of OPTN was analysed. None of the variants found were classified as disease causing and none of the haplotypes were associated to the disease in either patient group. There are just a few per cent of the Swedish primary open angle glaucoma patients with genetic variation associated to disease, in the genes analysed in this study. No association to exfoliative glaucoma was found. This indicates heterogeneity in the genetics of glaucoma when different subtypes and different populations are compared. Likely, there are genes still to be identified.