| Objective:The aim of this study is to illuminate pathogenic genes and mutations in two families with autosomal predominant high myopia,augmenting the gene mutation profile of high myopia(HM)and providing a reliable theoretical basis for early diagnosis and treatment,genetic counseling and prenatal diagnosis of HM.Methods:These two families were recruited from the Department of Ophthalmology of the affiliated Hospital of North Sichuan Medical College,Nanchong,China.After obtaining informed consent,each individual underwent review of medical history,detailed ocular and physical examinations.Whole exome sequencing(WES)was performed on selected members in Pedigree 1(proband+parents)and Pedigree 2(proband).Sanger sequencing was applied to verify the candidate mutations and study co-segregation within the pedigree.And 100 sporadic patients with HM and 200 normal controls were recruited at the ophthalmic clinic at the affiliated Hospital of North Sichuan Medical College to screen candidate mutations.Also,pathogenicity prediction of these mutations can be assessed by bioinformatic tools,including Polymorphism Phenotyping v2(PolyPhen-2),Protein Variation Effect Analyzer(PROVEAN)and Mutation Taster.Amino acid sequences alignment and protein domain prediction were performed by UGENE software and SMART(Simple Modular Architecture Research Tool)prediction tool,respectively.Results:1.Pedigree 1:A heterozygous nonsense mutation p.R287X was identified in the G-Protein-Coupled receptor 157(GPR157)gene between the proband and her father by WES,but not co-segregated with the high myopia phenotype in Pedigree 1.And it’s not present between 100 sporadic cases and 200 normal controls.Pedigree 2:WES revealed that the proband carried a p.G247S heterozygous mutation,a p.P409S heterozygous mutation and a p.C934W heterozygous mutation,located in the calpain-5(CAPN5),heat shock factor 4(HSF4)and USH2A gene(USH2A)genes,respectively.The mutation of CAPN5(p.G247S)is co-segregated with the high myopia phenotype in the model of incomplete penetrance,but there is no obvious co-segregating myopia phenotype associated with the two mutations(p.P409S;p.C934W)in Pedigree 2.2.Pedigree 1:Bioinformatics analysis indicated that p.R287X in GPR157 gene was predicted to be a pathogenic variant and highly conserved among different species.And p.R287X in GPR157 was located out the GPCR domain.Pedigree 2:Using bioinformatics software analysis,the detected mutations of p.C934W in USH2A and p.G247S in CAPN5 were predicted to be deleterious while p.P409S in HSF4 was a benign single nucleotide polymorphism.The position of the p.G247S and p.C934W missense mutations was at a highly conserved amino acid,while p.P409S position in mice happens to be the serine.In these 3 missense mutations,the p.G247S mutation in CAPN5 protein was located in the catalytic domain,and p.C934W in USH2A protein was located in the eighth Lam-EGF domain,while p.P409S in HSF4 protein was located out the HSF protein domain.Conclusion:1.The mutation in gene GPR157(p.R287X)might not be the pathogenic mutation in Pedigree 1,but it may be related to the onset of the proband and her father.2.CAPN5,not HSF4 or USH2A,might be the pathogenic gene in the pedigree 2. |
