Identification of genetic mutation in a Chinese pedigree with congenital cataract by whole-exome sequencing / 中华实验眼科杂志

Background Genetic mutation remains to be the most common cause of congenital cataract.Whole exon sequencing technology is an ideal method to detect the pathogenic gene mutations.Objective This study was to identify the pathogenic gene in a Chinese autosomal dominant congenital cataract (ADCC) family by whole-exome sequencing.Methods This study complied with Helsinki Declaration and the protocol was approved by Ethic Committee of Peking University Third Hospital.Informed consent was obtained from each subject before any medical examination.A cross-sectional study was designed.A Chinese ADCC family with 4 generations and 48 members were enrolled in Peking University Third Hospital,of which Ⅰ1 and Ⅰ2 died.The periphery blood of 8-10 ml was collected from each member of Ⅱ,Ⅲ and Ⅳ generations for the high throughput sequencing of genes using whole exon trapping and new sequencing technology,and the sequencing results were compared with the data of human HA PMAP8,dbSNP130 and 1000 Genome Project database.The synonymous mutation was filtered after reported common variants,and the false positive results of explicit sequencing were finally excluded by Sanger sequencing and then the candidate genes were identified.The mutation genes were screened to determine the pathogenic gene of this ADCC family.Results Eleven ADCC patients were found in this family,and the patients distributed in each generation with an equal chance for involvement in male and female subjects,which conformed to an autosomal dominant inheritance pattern.All the patients were nuclear cataract.Genome-wide whole-exome sequencing found that major intrinsic protein (MIP) gene was known genes of ADCC in initially identified candidate genes,so the Sanger was used to verify the MIP gene.The heterozygous mutation of MIP gene (chr12:56845250 C ＞ T) appeared to be the pathogenic cause of this ADCC family.The mutation occurred in the splice sites of the gene,resulting in the fourth exon coded-61 amino acids are replaced by leucine,histidine and serine,which lead to the abnormal truncated proteins.Conclusions The heterozygous mutation of MIP gene is the molecular pathogenesis of this Chinese ADCC family.

Analysis of GJA3 mutation associated with a Chinese family with autosomal dominant congenital cataract by whole-exome sequencing / 中华实验眼科杂志

Congenital cataract is one of the important reasons for the blindness of children,and most congenital cataracts are genetic.At present,thirty-nine genes have been identified relating to autosomal dominant congenital cataract (ADCC).Objective This study was to identify and analyze the virulence gene of a Chinese family pedigree with ADCC by whole-exome sequencing.Methods A Chinese ADCC family was recruited in Affiliated First Hospital of Zhengzhou University from August to September in 2014.The family disease history and clinical data were recorded.The peripheral venous blood of 10 ml was collected in 14 patients with congenital cataract and 14 families with normal phenotype,and the peripheral blood samples were obtained from 100 healthy examined people as controls.The genomic DNA was extracted form all subjects using standard phenol chlorum method,and proband DNA was screened by whole-exome sequencing.Then mutation locus of the candidate gene was selected after compared with the information of database in the proband.The mutation locus of the candidate gene from 14 normal families and 100 healthy controls were amplified and sequenced by PCR technique based on the primer sequence of mutation locus of proband to verify the pathogenic gene of this ADCC family.This study protocol was approved by Ethic Committee of Affiliated First Hospital of Zhengzhou University and complied with Helsinki Declaration.Written informed consent was obtained from subjects or custodian before any medical examination.Results The family had a total of 5 generations of 68 members,in which 20 subjects were found with congenital cataract.The inheritance mode consisted with autosomal dominant inheritance.Cortical cataract was found in both eyes in the patients.Whole-exome sequencing showed that the 143rd ribonucleotide A of exon 2 explicit factor of chromosome 13 GJA3 gene mutated into G (c.143A＞G) in the proband,which resulted in the 48th amino acids changed from glutamate into glycine (p.E48G).PCR amplification product sequencing displayed that the same mutation of DNA appeared in all the patients of this family,while not the same mutation was seen in the candidate genes of normal phenotype families and 100 healthy controls.Conclusions GJA3 gene c.143A＞G is a virulence mutation site in this ADCC family,it is a supplement of the mutation spectrum of GJA3 gene.

A recurrent mutation of CRYGD gene in a northern Chinese family with autosomal dominant congenital nuclear cataract / 中华实验眼科杂志

Background Congenital cataract is a major cause for blindness of childhood.Genetic gene mutation accounts for almost 1/3 of congenital cataract patients.The most common inheritance type is autosomal dominant congenital cataract (ADCC).Over 100 mutations in 26 genes have been found to be associated with ADCC.Objective This study was to identify the disease-causing gene mutation in a family with ADCC.Methods This study was approved by Ethic Committee of Beijing Tongren Hospital and followed Declaration of Helsinki.A northern Chinese family with autosomal dominant congenital nuclear cataract was entrolled in Beijing Tongren Hospital in January 2011.Ocular examinations were performed and periphery blood specimens were collected from each family member under the informed consent.Genomic DNA was extracted.Twenty-one microsatellite markers around 17 ADCC genes were selected for linkage analysis,and two-point LOD score was calculated.CRYGC gene and CRYGD gene were amplified and screened for mutations using direct sequencing.ProtScale software was used to analyze the changes of hydrophobicity of the mutated protein.Co-segregation of the observed change with the disease phenotype was further detected by restriction fragment length polymorphism (RFLP).Results This family included 20 members of 4 generations,and 9 patients were examined in serial 4 passages,which conformed to autosomal dominant inheritance pattern.Clinical examination revealed binocular congenital nuclear cataract in the 9 patients.Maximum two-point LOD score was 4.68 at marker D2S325 (θ=0).A known T→C change at position 127 of cDNA sequence was found by mutations screening of CRYGD gene.ProtScale programs showed an obvious increase of the local hydrophobicity in the mutant protein.RFLP results indicated that this missense mutation co-segregated with affected members of the family,but was absent in unaffected members and 100 unrelated controls.Conclusions c.T127C mutation of CRYGD gene appears to be the molecular pathogenesis of this ADCC family.Aberrant structure of mutant CRYGD protein caused by hydrophobicity change may lead to opacification of lens.

Detection of disease-causing gene in a Hui congential cataract pedigree by exon combined target region capture sequencing chip / 中华实验眼科杂志

Background Congenital cataract is an important cause of blindness and amblyopia in children,and about 50％ of congenital cataract is hereditary.Objective The aim of this study was to determine the diseasecausing gene of one Hui congenital cataract pedigree by using exon combined target region capture sequencing chip of eye diseases.Methods This study was approved by Ethic Committee of Ningxia People's Hospital and followed Declaration of Helsinki.One Hui congenital cataract pedigree was recruited in Ningxia Eye Hospital in 2011.All the disease history of the members in this family were collected and recorded,and the eye examinations were performed.The peripheral blood specimens were collected from family members and 300 healthy individuals for the extraction of DNA.Exon combined target region capture sequencing chip of eye diseases was used to screen the candidate diseasecausing mutations,then PCR and direct sequencing were used to confirm the disease-causing mutations.Results This H ui family included 61 members of 6 generations,and 18 patients were diagnosed in serial 5 passages,conforming to autosomal dominant inheritance pattern.Among 18 cataract patients,7 individuals were associated with nystagmus and strabismus,and 4 patients had high myopia.Eight candidate pathogenetic mutations were detected by exon combined target region capture sequencing chip of eye diseases and bioinformatics method,with 5 mutations in noncoding regions and 3 in coding regions.The mutation P24T of CYRGD gene was confirmed as pathogenic mutation of this pedigree by using PCR and direct sequencing methods.These mutations co-segregated with affected members of the family,and the mutations were not found in the unaffected family members and 300 unrelated controls.Conclusions P24T of CYRGD gene mutation is confirmed as pathogenic mutation of this pedigree.Exon combined target region capture sequencing chip provides a new approach to detect disease-causing mutations of congenital cataract with diversity clinical phenotypes.