OBJECTIVETo detect the disease-causing mutation in a pedigree affected with autosomal dominant congenital cataract.

METHODSGenomic 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.

RESULTSA 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.

CONCLUSIONThe nonsense mutation c.471G>A of the CRYGD gene probably underlies the congenital cataract in the pedigree.

Cataract ; etiology ; genetics ; Child ; Codon, Nonsense ; Humans ; Male ; Sequence Analysis, DNA ; gamma-Crystallins ; genetics

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.
Asian Continental Ancestry Group ; Cataract ; congenital ; genetics ; China ; Heterozygote ; Humans ; Mutation ; Pedigree ; gamma-Crystallins ; genetics

BACKGROUNDGammad-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.

METHODSgammaD-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.

RESULTSThe 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.

CONCLUSIONThe 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.

Animals ; Cattle ; Computer Simulation ; Hydrogen Bonding ; Models, Molecular ; Mutation ; Protein Structure, Tertiary ; gamma-Crystallins ; chemistry ; genetics ; physiology

OBJECTIVETo observe the correlation of gammaD-crystallin P23T mutant with lens ultrastructure of the hereditary coralliform cataract.

METHODSComplete 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).

RESULTSProtein 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.

CONCLUSIONIt is possible that the gammaD-crystallin P23T mutant is associated with abnormal crystals in lens and disorganization of lens epithelial cells.

Cataract ; congenital ; genetics ; pathology ; Female ; Humans ; Lens, Crystalline ; ultrastructure ; Male ; Pedigree ; Phenotype ; Point Mutation ; gamma-Crystallins ; genetics

OBJECTIVETo identify the disease-causing gene mutations in three Chinese pedigrees affected with congenital inherited cataract, in ordre to provide genetic counseling and prenatal diagnosis.

METHODSUsing exons combined target region capture sequencing chip to screen the candidate disease-causing mutations, Sanger sequencing was used to confirm the disease-causing mutations.

RESULTSFamily 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.

CONCLUSIONThe 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.

Cataract ; genetics ; Genetic Counseling ; Humans ; Mutation ; Pedigree ; Prenatal Diagnosis ; beta-Crystallin B Chain ; genetics ; gamma-Crystallins ; genetics

BACKGROUNDCongenital 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.

METHODSComplete 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).

RESULTSEleven 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.

CONCLUSIONSThe 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.

Cataract ; genetics ; pathology ; Female ; Genes, Dominant ; Genetic Linkage ; Humans ; Lens, Crystalline ; ultrastructure ; Male ; Microscopy, Electron ; Mutation, Missense ; gamma-Crystallins ; chemistry ; genetics

OBJECTIVETo identify the genetic defect for the autosomal dominant coralliform cataract affecting a four-generation Chinese family.

METHODSGenomic 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.

RESULTSThirteen 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.

CONCLUSIONThe 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.

Base Sequence ; Cataract ; diagnosis ; genetics ; DNA ; chemistry ; genetics ; DNA Mutational Analysis ; Family Health ; Female ; Genes, Dominant ; genetics ; Genetic Predisposition to Disease ; genetics ; Genetic Testing ; Humans ; Lod Score ; Male ; Mutation ; Pedigree ; Phenotype ; Protein Isoforms ; genetics ; gamma-Crystallins ; genetics