Analysis of MYOC gene mutation in a primary open angle glaucoma family from China

Abstract

Background Primary open angle glaucoma (POAG) is one of the frequent glaucomatous types,and genetic factor participates in pathogenesis and development of the disease.Recently,MYOC mutation was found to be associated with POAG.Objective This study was to describe the clinical and genetic findings in a POAG family from Luoyang,China.Methods This study protocol was approved by Ethic Committee of Affiliated First Hospital of Henan University of Science and Technology.The study adhered to Declaration of Helsinki.A POAG family with 29 members of 5 generations was surveyed and followed-up for 5-year duration.The mode of inheritance was determined by the pedigree analysis.The periphery blood sample was collected form 12 families and 100 health controls for the extraction of genomic DNA under the informed consent.The third exon and its flanking introns of MYOC were amplified,and quantitative real time PCR products were sequenced,and the structure and function of mutated gene were examined by restriction fragment length polymorphism analysis.The predicted effects of the detected variants on the secondary structure of MYOC protein were evaluated using Garnier-Osguthorpe-Robson (GOR) method,and homology analysis of protein was carried out by Blast software provided by National Center for Biotechnology Information (NCBI).Results This POAG family included 29 members of 5 generations,and the clinical data were not clear in 11 family members.Three individuals from 3 generations were determined POAG,another one was ocular hypertension,and 2 were carriers.Pedigree analysis appeared an autosomal dominant inheritance.In 12 subjects included 6 members genetically affected and 6 members with normal phenotype,the heterozygous mutation was found in the third exon of MYOC gene in 6 genetically affected members,which revealed a T→C transition at position 1021 (p.S341P),resulting in a switch of serine (Ser) to proline (Pro).It was a missense mutation abolished a CviKI-1 restriction site that segregated with the affected members.Secondary structure prediction of p.S341P suggested that myocilin protein was misfolded.Analysis of protein homology and switched Ser was conservative amine acid at position 1021 (p.S341P).No similar change was found in the 6 normal families and the normal controls.Conclusions Ser341Pro MYOC mutation is disease-causing factor in the POAG family of Luoyang.The clinical and genetic features of this mutation warrant further investigation.The mutation spectrum of MYOC is expanded to offer a better diagnosis and treatment for POAG patients. Key words: Glaucoma, open angle/genetics; Pedigree; MYOC gene; Mutation; Base sequence; Cytoskeletal protein; DNA mutational analysis; China