Identification of a novel CRYGC mutation in a pedigree affected with congenital cataracts / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a Chinese pedigree affected with congenital cataracts.@*METHODS@#Clinical data and peripheral blood samples were collected for the pedigree. Following extraction of genomic DNA, whole exome sequencing was carried out to detect genetic variants. Candidate variants were verified by familial co-segregation analysis and Sanger sequencing. Bioinformatics analysis was carried out to predict the function of mutant genes.@*RESULTS@#By comparing variants identified among affected and unaffected individuals, a heterozygous variant, c.110 G>C (p.R37P), was identified in exon 2 of the CRYGC gene among all patients, which also matched the criteria for potential disease-causing mutations. The result was confirmed by Sanger sequencing.@*CONCLUSION@#The c.110G>C variant of the CRYGC gene probably underlay the congenital cataracts in this pedigree.

Analysis of disease-causing gene mutation in three Chinese families with congenital inherited cataract / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify the disease-causing gene mutations in three Chinese pedigrees affected with congenital inherited cataract, in ordre to provide genetic counseling and prenatal diagnosis.</p><p><b>METHODS</b>Using exons combined target region capture sequencing chip to screen the candidate disease-causing mutations, Sanger sequencing was used to confirm the disease-causing mutations.</p><p><b>RESULTS</b>Family 1 was polymorphic cataract, family 2 was cerulean cataract, family 3 was coralliform cataract. The inheritance mode of the three pedigrees consisted with autosomal dominant inheritance. In family 1, a nonsense mutation of CRYβB2 gene c.463C>T in exon 6 result in a p.Q155X amino acid change. In family 2, a missense mutation of of CRYGD gene c.43C>T in exon 2 result in a p.R14C amino acid change. In family 3, a missense mutation of CRYGD gene c.70C>A in exon 2 result in a p.P23T amino aid change. No above-mentioned mutations were found in normal individuals.</p><p><b>CONCLUSION</b>The nonsense mutation c.463C>T (p.Q155X) of CRYβB2 gene, the heterozygous mutations c.43C>T(p.R14C) of CRYGD gene and c.70C>A( p.P23T) of CRYGD gene was the disease-causing gene mutation in family 1, 2 and 3 respectively, our results provid genetic counseling and prenatal diagnosis for these three families.</p>

A novel pathogenic mutation of CRYGD gene in a congenital cataract family / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect the disease-causing mutation in a pedigree affected with autosomal dominant congenital cataract.</p><p><b>METHODS</b>Genomic DNA was extracted and purified from peripheral blood samples from members of the pedigree and 100 healthy controls. Coding regions of 18 candidate genes were screened with PCR and Sanger sequencing. Identified mutations were verified among 100 healthy individuals to exclude single nucleotide polymorphisms.</p><p><b>RESULTS</b>A heterozygous nonsense mutation c.471G>A of the CRYGD gene, which resulted in p.Trp157Term, was identified in all three patients. The same mutation was not found in the two normal individuals from the family and 100 healthy controls. The nonsense mutation was predicted to be "disease causing" by Mutation t@sting program.</p><p><b>CONCLUSION</b>The nonsense mutation c.471G>A of the CRYGD gene probably underlies the congenital cataract in the pedigree.</p>

Analysis of single nucleotide polymorphisms of CRYGA and CRYGB genes in control population of western Indian origin.

Aim: Polymorphisms in gamma-crystallins ( CRYG ) can serve as markers for lens differentiation and eye disorders leading to cataract. Several investigators have reported the presence of sequence variations within crystallin genes, with or without apparent effects on the function of the proteins both in mice and humans. Delineation of these polymorphic sites may explain the differences observed in the susceptibility to cataract observed among various ethnic groups. An easier Restriction Fragment Length Polymorphism (RFLP)-based method has been used to detect the frequency of four single nucleotide polymorphisms (SNPs) in CRYGA / CRYGB genes in control subjects of western Indian origin. Materials and Methods: A total of 137 healthy volunteers from western India were studied. Examination was performed to exclude volunteers with any ocular defects. Polymerase chain reaction (PCR)-RFLP based method was developed for genotyping of G198A (Intron A), T196C (Exon 3) of CRYGA and T47C (Promoter), G449T (Exon 2) of CRYGB genes. Results: The exonic SNPs in CRYGA and CRYGB were found to have an allele frequency 0.03 and 1.00 for ancestral allele respectively, while frequency of non-coding SNP in CRYGA was 0.72. Allele frequency of T90C of CRYGB varied significantly ( P = 0.02) among different age groups. An in-silico analysis reveals that this sequence variation in CRYGB promoter impacts the binding of two transcription factors, ACE2 (Member of CLB2 cluster) and Progesterone Receptor (PR) which may impact the expression of CRYGB gene. Conclusions: This study establishes baseline frequency data for four SNPs in CRYGA and CRYGB genes for future case control studies on the role of these SNPs in the genetic basis of cataract.

Ultrastructure and crystallin mutant molecular modeling of hereditary coralliform cataract / 浙江大学学报·医学版

<p><b>OBJECTIVE</b>To observe the correlation of gammaD-crystallin P23T mutant with lens ultrastructure of the hereditary coralliform cataract.</p><p><b>METHODS</b>Complete ophthalmologic examinations were performed before lens extraction and lens samples were studied by transmission and scanning electric microscope respectively. Protein molecular modeling was performed using SWISS-MODEL(version 2.0).</p><p><b>RESULTS</b>Protein structure modeling demonstrated that the mutant caused a decrease in molecular final total energy and changes in the surface structure of gammaD-crystallin. Ultrastructure study revealed crystals deposited in lens, extensive granules dispersed in uncommon oval structure and the disorganization of lens epithelial cells.</p><p><b>CONCLUSION</b>It is possible that the gammaD-crystallin P23T mutant is associated with abnormal crystals in lens and disorganization of lens epithelial cells.</p>

Computer construction and analysis of protein models of the mutant gammaD-crystallin gene / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Gammad-crystallin plays an important role in human cataract formation. Being highly stable, gammaD-crystallin proteins are composed of two domains. In this study we constructed and analyzed protein models of the mutant gammaD-crystallin gene, which caused a special fasciculiform congenital cataract affecting a large Chinese family.</p><p><b>METHODS</b>gammaD-crystallin protein structure was predicted by Swiss-Model software using bovine gammaD-crystallin as a template and Prospect software using human betab2-crystallin as a template. The models were observed with a Swiss-Pdb viewer.</p><p><b>RESULTS</b>The mutant gammaD-crystallin structure predicted by the Swiss-Model software showed that proline23 was an exposed surface residue and P23T change made a decreased hydrogen bond distance between threonine23 and asparagine49. The mutant gammaD-crystallin structure predicted by the Prospect software showed that the P23T change exerted a significant effect on the protein's tertiary structure and yielded hydrogen bonds with aspartic acid21, asparagine24, asparagine49 and serine74.</p><p><b>CONCLUSION</b>The mutant gammaD-crystallin gene has a significant effect on the protein's tertiary structure, supporting that alteration of gamma-crystallin plays an important role in human cataract formation.</p>

Localization and screening of autosomal dominant coralliform cataract associated gene / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To identify the genetic defect for the autosomal dominant coralliform cataract affecting a four-generation Chinese family.</p><p><b>METHODS</b>Genomic DNA from the family members was typed for whole genomic linkage analysis. Two-point LOD scores were calculated using the LINKAGE program package (version 5.1). Mutation analysis of candidate genes was performed by direct sequencing.</p><p><b>RESULTS</b>Thirteen of the 38 individuals had congenital cataracts. The maximum two point LOD score, 3.5 at theta=0.1 was obtained for the marker D2S325. Mutation analysis of the gamma-crystallin gene cluster identified a C --> A mutation in exon 2 of gamma-D crystallin gene (CRYGD) associated with cataracts in this family. This mutation resulted in a substitution of threonine for proline at amino acid 23 (P23T) of the protein.</p><p><b>CONCLUSION</b>The results suggest that the coralliform cataract phenotype is due to a mutated gamma-D gene, and the sequence change is identical with that recently reported to be related with lamellar cataract, a distinct clinical entity, thus providing evidence that the same genetic defect may be associated with different opacity location. The pathogenesis needs further investigation.</p>

Autosomal dominant coralliform cataract related to a missense mutation of the gammaD-crystallin gene / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Congenital cataract is a sight-threatening disease that affects about 1 - 6 cases per 10000 live births and causes 10% - 30% of all blindness in children. About 25% of all cases are due to genetic defects. We identified autosomal dominant congenital coralliform cataracts-related genetic defect in a four-generation Chinese family.</p><p><b>METHODS</b>Complete ophthalmological examinations were performed prior to lens extraction. Lens samples were then studied by electron microscopy. Genomic DNA from family members were examined using whole-genomic linkage analysis, with two-point logarithm of odds (LOD) scores calculated using the Linkage program package (version 5.1). Mutation analysis of candidate genes was performed by direct sequencing. Finally, a three-dimensional protein model was predicted using Swiss-Model (version 2.0).</p><p><b>RESULTS</b>Eleven of the 23 examined individuals had congenital cataracts. Ultrastructure studies revealed crystal deposits in the lens, and granules extensively dispersed in transformed lens fiber cells. The maximum two-point LOD score, 3.5 at theta = 0.1, was obtained for the marker D2S325. Mutation analysis of the gamma-crystallin (CRYG) gene cluster identified a mutation (P23T) in exon 2 of gammaD-crystallin (CRYGD). Protein structure modeling demonstrated that the P23T mutation caused a subtle change on the surface of the gammaD protein.</p><p><b>CONCLUSIONS</b>The results suggest that the coralliform cataract phenotype is due to a mutated CRYGD gene, and that this sequence change is identical to one reported by Santhiya to be related to another distinct clinical condition, lamellar cataract. This study provides evidence that this same genetic defect may be associated with a different phenotype. This is the first report identifying the genetic defect associated with an autosomal dominant congenital coralliform cataract.</p>