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Purpose: To identify the genetic defect in a three-generation Chinese family with congenital cataracts., Methods: The phenotype of a three-generation Chinese family with congenital cataracts was recruited. Detailed family history and clinical data of the family were recorded. Candidate gene sequencing was performed to screen out the disease-causing mutation. Bioinformatics analysis was performed to predict the function of the mutant gene., Results: The phenotype of the family was identified as Y-suture cataract by using slit-lamp photography. Direct sequencing revealed a c.161G>C transversion in exon 1 of crystallin, alpha A (CRYAA). This mutation cosegregated with all affected individuals in the family and was not found in unaffected family members or in the 100 unrelated controls. Bioinformatics analysis indicated that the 54th amino acid position was highly conserved and the mutation R54P caused an increase in local hydrophobicity around the substitution site., Conclusions: This study identified a novel disease-causing mutation c.161G>C (p.R54P) in CRYAA in a Chinese family with autosomal dominant Y-suture cataracts. This is the first report relating a G→C mutation in CRYAA leading to congenital Y-suture cataract.

Purpose: The purpose of this study was to identify the disease-causing mutation and the molecular phenotype that are responsible for the presence of an autosomal dominant congenital nuclear cataract disease in a Chinese family., Methods: The family history and clinical data were recorded. The patients were given a physical examination and their blood samples were collected for DNA extraction. Direct sequencing was used to detect the mutation. Transcription analysis of the mutant crystallin, beta A1 (CRYBA1/A3) gene was performed to verify whether the defective mutation had influenced the splice of the mature mRNA., Results: The phenotype of the congenital cataract in the family was identified as a nuclear cataract type, by using slit-lamp photography. Direct sequencing revealed a novel mutation IVS3+2 T→G in CRYBA1/A3. This mutation co-segregated with all affected individuals in the family, but was not found in unaffected family members nor in the 100 unrelated controls. Transcription analysis of the mutant CRYBA1/A3 gene indicated that this mutation had influenced the splice of the mature mRNA., Conclusions: Our study identified a novel splice site mutation in CRYBA1/A3. This mutation was responsible for aberrant splicing of the mature mRNA and had caused the congenital nuclear cataracts in the family. This is the first report relating an IVS3+2 T→G mutation of CRYBA1/A3 to congenital cataracts.

Purpose: To identify the genetic defect associated with autosomal dominant congenital nuclear cataract in a Chinese family., Methods: Family history and clinical data were recorded. The genomic DNA was extracted from peripheral blood leukocytes. All the members were genotyped with microsatellite markers at loci considered to be associated with cataracts. Two-point logarithm of odds (LOD) scores were calculated by using the Linkage software after genotyping. Mutations were detected by DNA sequence analysis of the candidate genes. Effects of amino acid changes on the structure and function of proteins were predicted by bioinformatics analysis., Results: Evidence of a linkage was obtained at markers D1S514 (LOD score [Z]=3.48, recombination fraction [theta]=0.0) and D1S1595 (Z=2.49, theta=0.0). Haplotype analysis indicated that the cataract gene was close to these two markers. Sequencing of the connexin 50 (GJA8) gene revealed a T>C transition at nucleotide position c.92. This nucleotide change resulted in the substitution of highly conserved isoleucine by threonine at codon 31(I31T). This mutation co-segregated with all affected individuals and was not observed in unaffected or 110 normal unrelated individuals. Bioinformatics analysis showed that a highly conserved region was located at Ile31, and the mutation was predicted to affect the function and secondary structure of the GJA8 protein., Conclusion: A novel mutation in GJA8 was detected in a Chinese family with autosomal dominant congenital nuclear cataract, providing clear evidence of a relationship between the genotype and the corresponding cataract phenotype.

Purpose: We sought to identify the genetic defect in a four-generation Chinese family with autosomal dominant congenital coralliform cataracts and demonstrate the functional analysis of a candidate gene in the family., Methods: Family history data were recorded. Clinical and ophthalmologic examinations were performed on affected and unaffected family members. All the members were genotyped with microsatellite markers at loci considered to be associated with cataracts. Two-point LOD scores were calculated using the Linkage software after genotyping. A mutation was detected by direct sequencing, using gene-specific primers. Wild-type and mutant proteins were analyzed with online software., Results: Affected members of this family had coralliform cataracts. Linkage analysis was obtained at markers, D2S72 (LOD score [Z]=3.31, recombination fraction [theta]=0.0) and D2S1782 (Z=3.01, theta=0.0). Haplotype analysis indicated that the cataract gene was closely linked to these two markers. Sequencing the gammaD-crystallin gene (CRYGD) revealed a G>T transversion in exon 2, which caused a conservative substitution of Gly to Cys at codon 61 (P.G61C). This mutation co-segregated with the disease phenotype in all affected individuals and was not observed in any of the unaffected or 100 normal, unrelated individuals. Bioinformatic analyses showed that a highly conserved region was located around Gly61. Data generated with online software revealed that the mutation altered the protein's stability, solvent-accessibility, and interactions with other proteins., Conclusions: This is the first reported case of a congenital coralliform cataract phenotype associated with the mutation of Gly61Cys (P.G61C) in the CRYGD gene; it demonstrates a possible mechanism of action for the mutant gene.

Purpose: To identify the genetic defect in a four-generation Chinese family with autosomal dominant congenital nuclear cataract. Methods: Family history data were recorded. Clinical and ophthalmologic examinations were performed on family members. All the members were genotyped with microsatellite markers at loci associated with cataracts. Linkage analysis was performed after genotyping. Candidate genes were screened for mutation using direct sequencing. Results: Linkage analysis was obtained at markers D1S1653 (LOD score [ Z] = 1.50, recombination fraction [θ] = 0.0) and D1S498 (LOD score Z = 0.90, recombination fraction [θ] = 0.0), which encompasses the connexin 50 gene ( GJA8). Sequencing the coding regions of GJA8 revealed a novel, heterozygous c.773C>T transition that resulted in the substitution of a highly conserved serine by phenylalanine at codon 258 (S258F). Bioinformatics analysis showed that the mutation altered the hydrophobicity and secondary structure of the protein. This mutation co-segregated with the disease phenotype in all affected individuals and was not found in the unaffected family members or in 100 normal unrelated individuals. Conclusions: This study has identified a novel missense mutation located in the carboxyl terminus of GJA8 (S258F) associated with autosomal dominant nuclear cataract. [ABSTRACT FROM AUTHOR]

A notable behavioural feature of X-linked retinoschisis (XLRS) is extensive structural schisis (splitting) of the outer plexiform and inner nuclear layers of the neurosensory retina, which is partly combined with complications related to vitreous hemorrhage, macular holes and retinal detachment. The present study aimed to identify the pathogenic gene mutation in a three-generation Chinese family with XLRS by whole-exome sequencing (WES). The clinical information of a three-generation Chinese family with cases of XLRS was collected. WES was performed for the proband. A comparison with the human reference genome sequence (hg38) and bioinformatic analysis were performed to reveal putative variants and Sanger sequencing was applied to verify mutations in this family and healthy control participants. Intraretinal cystic spaces were detected by optical coherence tomography imaging. Structures of the wild-type and mutant retinoschisin 1 (RS1) protein were modelled by PyMol. Almost all patients had a history of vision loss and abnormal blue-purple colour vision; however, the phenotypes of the 4 patients were distinctly different. There was no linear correlation between phenotypic severity and age. A recurrent RS1 (Xp22.2) mutation (NM_000330: c.559C>T) was detected, resulting in the p.Q187X variant. According to the protein model, this variant is likely pathogenic. The present study was the first to report that RS1:c.559C>T induces XLRS in a three-generation Chinese pedigree, with the mutation leading to premature termination of translation of the RS1 protein. WES was able to diagnose XLRS, which has the characteristics of clinical and genetic heterogeneity. [ABSTRACT FROM AUTHOR]

Congenital cataracts is the most common cause of visual impairment and blindness in children. Although there have been extensive studies into the pathogenesis of congenital cataracts, the pathogenic mechanism underlying the recurrent variant CRYBB2:c.62T>A(p.I21N) has not been previously reported. Thus, the present study aimed to use whole-exome sequencing (WES) to identify potential genetic variants and investigate how they may have induced the occurrence of cataracts in a four-generation Chinese family with congenital nuclear cataracts. The medical history of this family was recorded and WES was conducted for one proband. Sanger sequencing was used to verify the presence of the putative variant in all participants. PolyPhen-2, SIFT and ProtScale were used to analyze the effect of the identified variants on protein function and hydrophobicity, and Pymol was used to show the structure of the wild-type (Wt) and mutant β-crystallin B2 (CRYBB2) protein. Full-length Wt-CRYBB2 or mutant-CRYBB2 (I21N-CRYBB2) were fused to green fluorescent protein (GFP), and the recombinant plasmids were transfected into HeLa cells. Reverse transcription-quantitative PCR and western blotting were used to detect the expression levels of CRYBB2 mRNA and protein. Immunofluorescence and flow cytometry analyses were used to detect protein localization and apoptosis, respectively. A recurrent variant CRYBB2:c.62T>A(p.I21N) was identified in a four-generation Chinese family with congenital nuclear cataracts. Multiple-sequence alignment of CRYBB2 demonstrated that codon 21 was highly conserved. Pymol revealed that the structure of the I21N-CRYBB2 protein was distinct from that of Wt-CRYBB2. PolyPhen-2 predicted that it had a variant provean score 1.0, suggesting it was 'probably damaging', and SIFT predicted it had a variant provean score of -5.113, indicating it was 'deleterious'. ProtScale indicated that the hydrophobicity of the mutation site was significantly reduced. The protein expression levels of the I21N-CRYBB2 were decreased compared with the Wt-CRYBB2. Immunofluorescence analysis revealed that the variant I21N-CRYBB2 protein tended to accumulate around the nucleus, and flow cytometry analysis indicated that it increased cell apoptosis. Furthermore, I21N-CRYBB2 induced the activation of the unfolded protein response (UPR). In conclusion, a pathogenic variant of CRYBB2:c.62T>A(p.I21N) was identified via WES in a four-generation Chinese family with congenital nuclear cataracts. Through biological analysis, it was found that the variant induced abnormal protein aggregation, activated the UPR and triggered excessive cell apoptosis, which may lead to the occurrence of congenital nuclear cataracts in this family. [ABSTRACT FROM AUTHOR]