Investigation For Heredity And OPTN Gene Mutation Of Primary Open Angle Glaucoma

Glaucoma is the second leading cause of blindness which affect over 70 million people worldwide. Primary open angle glaucoma (POAG) is the most common subtype and the first reason of blindness of black man in America. Moreover, There are many subjects suffering from POAG in China. POAG is a kind of complex latent disease characterized by chronic progressive optic ganglion cells apoptosis and visual field injury. Thus, It is difficult to diagnoses and treat in early period. Although it is not yet wholly understood about the mechanism of glaucoma, more and more evidences suggest that there is an association between heredity and gene mutations with pathogenesis of glaucoma. In spite of great progress of glaucoma genetics, the hereditary form of POAG is not clear. on the other hand, about ten genes loci were found to associate with POAG after the discovery that TIGR gene links to POAG based on molecular genetics assay. The optineurin(optic neuropathy inducing, OPTN), a novel gene linked to POAG, was found by Reiaze and his colleagues in 2002. Mutations in the OPTN gene were found in 16.7% of 54 families with autosomal dominant adult-onset POAG, and in 13.6% of the sporadic glaucoma cases. However, there is no report about mutations of OPTN gene in Chinese POAG cases.Purpose:To investigate the relationship between POAG and the mutations of OPTN gene in China, a POAG family in ChongQings was followed up, and the blood specimens of POAG individuals and controls were collected and processed by molecular biological strategy.Methods: 1. To analyze the genetic form of the pedigree according to Mandalian hereditary rules after we collect a great family with POAG. 2. The genomic DNA was extracted from the peripheral blood of all samples. A total of 4350bp of 13 encoding exons and introns beside exons were amplified by PCR using the sequence-specific primers.3. Automated sequencing method was used to screen and identify mutations of OPTNgene of both POAG subjects and first degree relatives in this family.4. Restriction endonuclease analysis was used to detect the same mutation in the controls samples.5. The frequency of genetypes between POAG group and controls were compared by statistics.6. The sequence alterations were analyzed by bioinfomatics.Results:1. This pedigree could be traced to 54 members in 5 generations, Including 29 males and 25 females. There are 17 patients with POAG, including 11 males and 6 females. Six patients had died in this family. The four continuous generations exist patients with POAG. The prevalence rate is 31%.2. The encoding exons of OPTN gene of all alive patients and collected first degree relatives were directly automatic- sequenced, it is found that 3 patients ( IV-5,III-5, III-4) and one first degree relative(IV-7) exist the 412G>A mutation in 4th exon. II-5 patient has a 603T>A alteration. III-5 was found that two C pyrimidine insertions between 1267-1268 site and 1271-1272 of 10th exon, respectively. III-3 exist 1537-1538ins (insert) C alteration. 1878-1879ins A had been found in a first degree relative (V-3).3. No same mutations of OPTN gene were detected in 32 controls, except one person has a 412G>A mutation. 4. Rate of observed mutations in POAG family is 20%, no mutations were found in controls. The mutation rate of POAG family group is obviously higher than that in the controls group( X2=6.93> X20.016.63,P<0.01).5. Bioinformatics analysis indicated that all mutations will result in the alteration of OPTN protein structure which may underlies its abnormal functional domain except for 412G>A mutation.Conclusions:1. The form of heredity in this POAG family in Zhong county of Chongqing is autosomal dominant trait, and there must be a abnormal gene which result in POAG in this family.2. The mutation of OPTN gene is responsible for onset of POAG in this pedigree.3. Function abnormality of OPTN protein, which are induced by change of the structure and functional domains caused by mutation of OPTN, may be an important m...