Evaluation of mutant alleles of MYOC and CYP1B1 genes in patients with primary open-angle glaucoma

Author(s)

Carolina Ayumi Braghini

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2012-02-29

Examining board members

Mônica Barbosa de Melo; Edi Lúcia Sartorato; Cláudia Vianna Maurer Morelli

• Advisor: Mônica Barbosa de Melo

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 (AU)

• FAPESP's process: 09/15223-0 - Evaluation of mutant alleles of MYOC and CYP1B1 genes in patients with primary open-angle glaucoma
• Grantee: Carolina Ayumi Braghini
• Support Opportunities: Scholarships in Brazil - Master