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A novel p.R890C mutation in EPHA2 gene associated with progressive childhood posterior cataract in a Chinese family.

ABSTRACT: AIM:To identify the genetic defect in a Chinese family with bilateral progressive childhood posterior cataract. METHODS:A two-generation family was recruited in this study. Family history and clinical data were recorded. All reported candidate genes associated with congenital posterior cataract were screened by direct DNA sequencing. RESULTS:All affected individuals presented posterior opacities in the lens. Direct sequencing of the candidate genes showed a heterozygous c. 2668C>T variation in EPHA2 gene, which resulted in the replacement of arginine by cysteine at codon 890 (p. R890C). This mutation was found in two affected individuals, but was not observed in 200 normal controls. CONCLUSION:We report a novel mutation (p. R890C) in the EPHA2 receptor tyrosine kinase gene. The finding expands the mutation spectrum of EPHA2 in association with posterior cataract.

SUBMITTER: Shentu XC

PROVIDER: S-EPMC3580246 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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A novel p.R890C mutation in EPHA2 gene associated with progressive childhood posterior cataract in a Chinese family.

Shentu Xing-Chao XC Zhao Su-Juan SJ Zhang Li L Miao Qi Q

International journal of ophthalmology 20130218 1

<h4>Aim</h4>To identify the genetic defect in a Chinese family with bilateral progressive childhood posterior cataract.<h4>Methods</h4>A two-generation family was recruited in this study. Family history and clinical data were recorded. All reported candidate genes associated with congenital posterior cataract were screened by direct DNA sequencing.<h4>Results</h4>All affected individuals presented posterior opacities in the lens. Direct sequencing of the candidate genes showed a heterozygous c. ...[more]

PMID: 23447127

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Project description:BACKGROUND:Congenital cataract is the leading cause of blindness in children worldwide. Approximately half of all congenital cataracts have a genetic basis. Protein aggregation is the single most important factor in cataract formation. METHODS:A four-generation Chinese family diagnosed with autosomal dominant congenital cataracts and microphthalmia was recruited at the Shengjing Hospital of China Medical University. Genomic DNA was extracted from the peripheral blood of the participants. All coding exons and flanking regions of seven candidate genes (CRYAA, CRYBA4, CRYBB2, CRYGC, GJA8, MAF, and PITX3) were amplified and sequenced. Restriction fragment length polymorphism (RFLP) assays were performed to confirm the candidate causative variant, c.35G?>?T in the CRYAA gene. We constructed pcDNA3.1(+)-CRYAA expression plasmids containing either the wild-type or the R12L mutant alleles and respectively transfected them into HEK293T cells and into HeLa cells. Western blotting was performed to determine protein expression levels and protein solubility. Immunofluorescence was performed to determine protein sub-cellular localization. RESULTS:A heterozygous variant c.35G?>?T was identified in exon 1 of CRYAA, which resulted in a substitution of arginine to leucine at codon 12 (p.R12L). The nucleotide substitution c.35G?>?T was co-segregated with the disease phenotype in the family. The mutant R12L-CRYAA in HEK293T cells showed a significant increase in the expression level of the CRYAA protein compared with the wild-type cells. Moreover, a large amount of the mutant protein aggregated in the precipitate where the wild-type protein was not detected. Immunofluorescence studies showed that the overexpressed mutant CRYAA in HeLa cells formed large cytoplasmic aggregates and aggresomes. CONCLUSIONS:In summary, we described a case of human congenital cataract and microphthalmia caused by a novel mutation in the CRYAA gene, which substituted an arginine at position 12 in the N-terminal region of ?A-crystallin. The molecular mechanisms that underlie the pathogenesis of human congenital cataract may be characterized by the prominent effects of the p.R12L mutation on ?A-crystallin aggregation and solubility. Our study also expands the spectrum of known CRYAA mutations.

Project description:PurposeTo identify a novel disease-causing mutation of the GJA3 (gap junction alpha-3 protein) gene in a Chinese family with autosomal dominant congenital cataract (ADCC).MethodsOne family was examined clinically. After informed consent was obtained, genomic DNA was extracted from the venous blood of all participants. Genetic linkage analysis was performed on the known genetic loci for ADCC with a panel of polymorphic markers, and then mutations were screened by direct sequencing. Whenever substitutions were identified in a patient, high-resolution melt curve analysis (HRM) was performed on all available family members and 100 normal controls. Bioinformatics analysis was undergone by the Garnier-Osguthorpe-Robson (GOR) and the PolyPhen (polymorphism phenotyping) programs to predict the effect of variants detected on secondary structure and protein function of the GJA3 protein.ResultsClinical examination and pedigree analysis revealed one four-generation family with congenital nuclear coralliform cataracts. Significant two-point LOD (linkage odd disequilibrium) score was generated at marker D13S292 (Z(max)=2.51, θ=0), and further linkage and haplotype studies confined the disease locus to 13q11-13. Mutations screening of GJA3 in this family revealed an A→T transversion at position 563 (p.N188I) of the cDNA sequence. This novel missense mutation co-segregated with the affected members of the pedigree, but is not present in the unaffected relatives or 100 normal individuals. Secondary structure prediction suggested that the mutant GJA8 188I would replace three turns "T" with three β sheet "E" at amino acid 189-191 and a β sheet "E" with a turn "T" at position 194.ConclusionsNovel missense mutation in the second extracellular loop (E2) was detected, causing coral-like opacities involving embryonic and fetal nucleus surrounded by blue punctate opacities in the cortical zone of the lens. The results further suggested that the extracellular loop was the mutation hotspot of GJA3.

Dataset Information

A novel p.R890C mutation in EPHA2 gene associated with progressive childhood posterior cataract in a Chinese family.

Publications

A novel p.R890C mutation in EPHA2 gene associated with progressive childhood posterior cataract in a Chinese family.

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