Study On The Gene Mutation Of TIGR In Primary Open Angle Glaucoma, Their Relatives And The Normal Control In Chongqing

It is not yet wholly understood the mechanism of glaucoma, which is the second eye disease leading to blindness. A lot of efforts have been made on trabecular-meshwork inducible glucocorticoid response (TIGR) gene mutations, since TIGR gene located on chromosome 1q23-24 was selected as a gene causing primary open angle glaucoma (POAG). TIGR gene contains more than 30 sorts of DNA sequence variants including at least 16 variants closely related to POAG. Studies on people from different human races or from different living regions have reported there were varied mutation sites and prevalence of TIGR gene. Besides, it is still not known about the role of TIGR gene mutation in the occurrence of POAG among Chinese. The purpose of our study was to investigate the relationship between TIGR gene mutation and POAG in Chongqing where inheriting informations in population were stable. It will help us to understand the role of TIGR gene mutation in the occurrence of POAG among Chinese. Furthermore, with development of the human genome project and by advanced technique of modern molecular biology and molecular genetics, a new way for effective prevention and treatment of POAG might be found by deeply understanding the molecular mechanism of POAG.METHODS:In this study, genomic DNA was extracted from 1 ml whole blood of patients with POAG, their relatives and normal controls. The coding sequence of TIGR was screened for sequence alterations using polymerase chain reaction(PCR) followed by single-strand conformation polymorphism (SSCP).Samples corresponding to bands of altered mobility were sequenced.The sequence alterations were analyzed by bioinformatics.RESULTS:1,While TIGR gene mutations were screened in 5 patients among 15 patients with POAG in Chongqing, 2 cases of TIGR gene mutation were found in 10 persons whose family happened POAG. However, no TIGR gene mutation was detected in 20 people of control group.2,Four altered sequences were identified in our study. The mutation sites Ser55Thr, Asp247Stop and in 49021 c-t alteration were newly discovered in our study. The 63155 c-t alternation was reported as a polymorphism site.3,Bioinformatics analysis indicated that the mutations in structural domain might lead to the changes of the amino acid sequence coded, second structure of protein, isoelectric point and antigen binding site.CONCLUSIONS:The mutations of TIGR gene only were observed in patients with POAG and their relatives. There were four JOAG (Juvenile Onset Open Angle Glaucoma) in five patients occurred TIGR gene mutation. It indicated that TIGR gene mutations were closely related to the JOAG in Chongqing. The mutation frequency of TIGR in the relative of patient with POAG was higher than that of in control subjects. Furthermore, after analyzing the amino acid sequence, second structure of protein, isoelectric point and antigen binding site of altered gene, we suggested that the alteration of structure and biological activity of TIGR protein resulted from gene mutation might be one of the important factors involved in the pathogenesis of POAG.