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Mutation analysis of 12 genes in Chinese families with congenital cataracts.

ABSTRACT: PURPOSE: To identify mutations in 12 genes in Chinese families with congenital cataracts. METHODS: Twenty five families with congenital cataracts involved in this study. The coding exons and adjacent intronic regions of 12 genes were analyzed by cycle sequencing, including the alpha A crystallin (CRYAA), alpha B crystallin (CRYAB), beta A1 crystallin (CRYBA1), beta A4 crystallin (CRYBA4), beta B1 crystallin (CRYBB1), beta B2 crystallin (CRYBB2), beta B3 crystallin (CRYBB3), gamma C crystallin (CRYGC), gamma D crystallin (CRYGD), gamma S crystallin (CRYGS), alpha 3 gap junction protein (GJA3), and alpha 8 gap junction protein (GJA8) genes. Novel variants were further evaluated in 96 normal controls. RESULTS: Nine mutations were identified in 10 of the 25 families (40%), including 5 novel (c.350_352delGCT in CRYAA, c.205C>T in CRYAB, c.106G>C in CRYGD, c.77A>G in CRYGS, c.1143_1165del23 in GJA3) and 4 known (c.292G>A in CRYAA; c.215+1G>A and c.272_274delGAG in CRYBA1, and c.176C>T in GJA3). All novel mutations were predicted to be pathogenic and were not present in 96 controls. CONCLUSIONS: Mutations in the 12 genes encoding crystallins and connexins were responsible for 40% Chinese families with congenital cataracts. Our results enriched our knowledge on the molecular basis of congenital cataracts in Chinese population.

SUBMITTER: Sun W

PROVIDER: S-EPMC3159683 | biostudies-literature | 2011

REPOSITORIES: biostudies-literature

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Mutation analysis of 12 genes in Chinese families with congenital cataracts.

Sun Wenmin W Xiao Xueshan X Li Shiqiang S Guo Xiangming X Zhang Qingjiong Q

Molecular vision 20110816

<h4>Purpose</h4>To identify mutations in 12 genes in Chinese families with congenital cataracts.<h4>Methods</h4>Twenty five families with congenital cataracts involved in this study. The coding exons and adjacent intronic regions of 12 genes were analyzed by cycle sequencing, including the alpha A crystallin (CRYAA), alpha B crystallin (CRYAB), beta A1 crystallin (CRYBA1), beta A4 crystallin (CRYBA4), beta B1 crystallin (CRYBB1), beta B2 crystallin (CRYBB2), beta B3 crystallin (CRYBB3), gamma C ...[more]

PMID: 21866213

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Project description:Purpose:To identify mutations in crystallin genes in Chinese families with congenital cataracts. Methods:Forty-two unrelated families with non-syndromic congenital cataracts were enrolled in this study. The coding exons and adjacent intronic regions of crystallin genes, including CRYAA, CRYAB, CRYBA1, CRYBA4, CRYBB1, CRYBB2, CRYBB3, CRYGC, CRYGD and CRYGS, were analyzed with Sanger sequencing. Novel variants were further evaluated in 112 ethnically matched controls. To confirm the novel mutations, short tandem repeat (STR) haplotypes were constructed to check the cosegregation with congenital cataract. The pathogenic potential of the novel mutations were assessed using bioinformatics tools, including Sorting Intolerant From Tolerant v5.1.1 (SIFT), Polymorphism Phenotyping v2 (PolyPhen-2), and Human Splicing Finder. The pathogenicity of all the mutations was evaluated according to the guidelines of the American College of Medical Genetics (ACMG) and InterVar software. Results:Seven previously reported mutations in crystallin genes identified in ten unrelated families were associated with the congenital nuclear cataracts. Four novel mutations in crystallin genes, including c.35G>T (p.R12L) in CRYAA, c.463C>A (p.Q155K) in CRYBB2, IVS1 c.10-1G>A in CRYGC, and c.346delT (p.F116Sfsx29) in CRYGD, were identified in four unrelated families with congenital cataracts. These mutations cosegregated with all affected individuals in each family were not observed in the unaffected family members or in the 112 unrelated controls. All four novel mutations were categorized as disease "likely pathogenic" except IVS1 c.10-1G>A in CRYGC "pathogenic" using InterVar software in accordance with the ACMG standard. Mutations in crystallin genes were responsible for 33.33% of the Chinese families with congenital cataracts in this cohort. Conclusions:In this study, we identified four novel mutations in crystallin genes in Chinese families with congenital cataracts. The results expand the mutational spectrum of crystallin genes, which may be helpful for the molecular diagnosis of congenital cataracts in the era of precision medicine.

Project description:BACKGROUND:Congenital cataract, a kind of cataract presenting at birth or during early childhood, is a leading cause of childhood blindness. To date, more than 30 genes on different chromosomes are known to cause this disorder. This study aimed to identify the HSF4 mutations in a cohort from Chinese families affected with congenital cataracts. METHODS:Forty-two unrelated non-syndromic congenital cataract families and 112 ethnically matched controls from southeast China were recruited from the southeast of China. We employed Sanger sequencing method to discover the variants. To confirm the novel mutations, STR haplotypes were constructed to check the co-segregation with congenital cataract. The pathogenic potential of the novel mutations were assessed using bioinformatics tools including SIFT, Polyphen2, and Human Splicing Finder. The pathogenicity of all the mutations was evaluated by the guidelines of American College of Medical Genetics and InterVar software. RESULTS:No previously reported HSF4 mutations were found in all the congenital cataract families. Five novel HSF4 mutations including c.187 T?>?C (p.Phe63Leu), c.218G?>?T (p.Arg73Leu), c.233A?>?G (p.Tyr78Cys), IVS5 c.233-1G?>?A and c.314G?>?C (p.Ser105Thr) were identified in five unrelated families with congenital cataracts, respectively. These mutations co-segregated with all affected individuals in each family were not observed in the unaffected family members or in 112 unrelated controls. All five mutations were categorized to be the disease "pathogenic" according to ACMG guidelines and using InterVar software. Mutations in the HSF4 were responsible for 11.90% Chinese families with congenital cataracts in our cohort. CONCLUSIONS:In the study, we identified five novel HSF4 mutations in Chinese families with congenital cataracts. Our results expand the spectrum of HSF4 mutations causing congenital cataracts, which may be helpful for the molecular diagnosis of congenital cataracts in the era of precision medicine.

Project description:Purpose:To identify disease-causing gene mutations in 21 northern Chinese families with congenital cataracts. Methods:Medical record collection and ophthalmologic examinations were conducted for 21 families with congenital cataracts. A volume of 5 ml of peripheral blood was drawn from each participant for genomic DNA isolation. Thirty-four known candidate genes for congenital cataracts were analyzed in the probands of 21 families with targeted next-generation sequencing (NGS). Bioinformatics analysis of the sequence variants was performed through computational predictive programs. Sanger sequencing was used to perform the cosegregation analysis. Genotyping and haplotype analyses were performed in two patients with a p.V44M mutation in the GJA8 gene. Results:Twelve disease-causing mutations were detected in 13 of the 21 patients, and the mutation detection rate was 61.9%. The 12 gene mutations included one nonsense, one splice site, seven missense, and three insert and deletion (INDELs) mutations. Four mutations were novel. Of the 13 patients with pathogenic gene mutations, five (38.5%) were affected by mutations in lens crystallin genes, three (23%) were affected by mutations in connexin genes, three (23%) were affected by mutations in transcription factor genes, one (7.7%) was affected by a mutation in a transmembrane transporter gene, and one (7.7%) was affected by a mutation in a chromatin-modifying protein gene. Two families carried the p.V44M mutation in the GJA8 gene. Haplotype analysis revealed a chromosome region of 475 kb containing the mutation in the GJA8 gene was harbored by two families. Conclusions:Compared with traditional Sanger sequencing, targeted NGS for genetic testing of congenital cataracts markedly increases the mutation detection rate and is cost-effective. The p.V44M mutation in the GJA8 gene was the most common mutation and was due to a founder effect within the Chinese cohort studied. The results of this study expand the gene mutation spectrum of congenital cataracts.

Project description:This study was performed to investigate the genetic determinants of autosomal recessive congenital cataracts in large consanguineous families.Affected individuals underwent a detailed ophthalmological examination and slit-lamp photographs of the cataractous lenses were obtained. An aliquot of blood was collected from all participating family members and genomic DNA was extracted from white blood cells. Initially, a genome-wide scan was performed with genomic DNAs of family PKCC025 followed by exclusion analysis of our familial cohort of congenital cataracts. Protein-coding exons of CRYBB1, CRYBB2, CRYBB3, and CRYBA4 were sequenced bidirectionally. A haplotype was constructed with SNPs flanking the causal mutation for affected individuals in all four families, while the probability that the four familial cases have a common founder was estimated using EM and CHM-based algorithms. The expression of Crybb3 in the developing murine lens was investigated using TaqMan assays.The clinical and ophthalmological examinations suggested that all affected individuals had nuclear cataracts. Genome-wide linkage analysis localized the causal phenotype in family PKCC025 to chromosome 22q with statistically significant two-point logarithm of odds (LOD) scores. Subsequently, we localized three additional families, PKCC063, PKCC131, and PKCC168 to chromosome 22q. Bidirectional Sanger sequencing identified a missense variation: c.493G>C (p.Gly165Arg) in CRYBB3 that segregated with the disease phenotype in all four familial cases. This variation was not found in ethnically matched control chromosomes, the NHLBI exome variant server, or the 1000 Genomes or dbSNP databases. Interestingly, all four families harbor a unique disease haplotype that strongly suggests a common founder of the causal mutation (p<1.64E-10). We observed expression of Crybb3 in the mouse lens as early as embryonic day 15 (E15), and expression remained relatively steady throughout development.Here, we report a common ancestral mutation in CRYBB3 associated with autosomal recessive congenital cataracts identified in four familial cases of Pakistani origin.

Project description:Purpose: To broaden the mutation and phenotype spectrum of the GJA8 and CHMP4B genes and to reveal genotype-phenotype correlations in a cohort of Chinese patients with congenital cataracts (CCs). Methods: Six Chinese Han families with CCs inherited in an autosomal dominant (AD) pattern were recruited for this study. All patients underwent full ocular examinations. Genomic DNA was extracted from the leukocytes of peripheral blood collected from all available patients and their unaffected family members. Whole-exome sequencing (WES) was performed on all probands and at least one of their parents. Candidate variants were further confirmed by Sanger sequencing. Bioinformatic analysis with several computational predictive programs was performed to assess the impacts of the candidate variants on the structure and function of the proteins. Results: Four heterozygous candidate variants in three different genes (CRYBB2, GJA8, and CHMP4B) were identified in affected individuals from the six families, including two novel missense variants (GJA8: c.64G > C/p. G22R, and CHMP4B: c.587C > G/p. S196C), one missense mutation (CRYBB2: c.562C > T/p. R188C), and one small deletion (GJA8: c.426_440delGCTGGAGGGGACCCT/p.143_147delLEGTL). The three missense mutations were predicted as deleterious in all four computational prediction programs. In the homologous model, the GJA8: p.143_147delLEGTL mutation showed a sequence deletion of five amino acids at the cytoplasmic loop of the Cx50 protein, close to the third transmembrane domain. Patients carrying mutations in the same gene showed similar cataract phenotypes at a young age, including total cataracts, Y-sutural with fetal nuclear cataracts, and subcapsular cataracts. Conclusion: This study further expands the mutation spectrum and genotype-phenotype correlation of CRYBB2, GJA8, and CHMP4B underlying CCs. This study sheds light on the importance of comparing congenital cataract phenotypes in patients at the same age stage. It offers clues for the pathogenesis of CCs and allows for an early prenatal diagnosis for families carrying these genetic variants.

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Mutation analysis of 12 genes in Chinese families with congenital cataracts.

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Mutation analysis of 12 genes in Chinese families with congenital cataracts.

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