A new locus for autosomal dominant congenital coronary cataract in a Chinese family maps to chromosome 3q.

PURPOSE: To identify the genetic defect in an autosomal dominant congenital coronary cataract family (ADCCC). METHODS: A Chinese family with ADCC was identified and characterized. All the members were genotyped with microsatellite markers at genes and loci that were considered to be associated with hereditary cataracts. Linkage analysis was performed after genotyping. Two-point Logarithm of odds (LOD) scores were calculated using MLINK software, from the LINKAGE program package. Multipoint parametric and non-parametric linkage were performed via the program MERLIN. RESULTS: Linkage analysis provided evidence for a genetic locus for the ADCC on chromosome 3q. The maximum Two-point LOD score was 3.01 (theta=0) for two close markers. CONCLUSIONS: The mapping of the congenital cataracts in a Chinese family locus to chromosome 3q.

Autosomal-dominant cerulean cataract in a chinese family associated with gene conversion mutation in beta-B2-crystallin.

AIMS: Our purpose was to identify the genetic defect in a Chinese cerulean cataract family. METHODS: After obtaining informed consent, genomic DNA was extracted from leukocytes. Genotyping and 2-point linkage analysis were carried out using the MLINK component of the LINKAGE program package version 5.10. Mutational analysis of the candidate gene was performed by bidirectional sequencing. The structure homology modeling of the mutant protein was based on Swiss-Model Serve, and its structure was displayed and compared with native beta-B2-crystallin using the RasMol software. RESULTS: The disease locus was mapped within a 4.05-cM interval on 22q11.22-22q12.1. By sequencing, a cytosine to thymine transition (NM_000496.2:c.463C>T) was detected in exon 6 of CRYBB2, which resulted in the insertion of a premature stop codon (p.Q155X). In addition, there existed another transition (NM_000496.2:c.471C>T) in the same exon, which does not change the amino acid sequence. Neither NM_000496.2:c.463C>T nor NM_000496.2:c.471C>T were found in 171 normal Chinese controls. The homology modeling showed that the second structure of the mutant protein was different from that of native human beta-B2-crystallin. CONCLUSIONS: This is the first report of congenital cerulean cataract associated with a mutation in CRYBB2 in a Chinese family. This finding further strengthens the association between CRYBB2 and cerulean cataracts. Two transitions, NM_000496.2:c.463C>T and NM_000496.2:c.471C>T, in CRYBB2 are identical to the sequence of CRYBB2P1, which has over 97% homology to CRYBB2. This supports the possibility of gene conversion between CRYBB2 and CRYBB2P1 as a mechanism responsible for congenital cataract.

[A novel missense mutation in MIP gene resulted in polymorphic cataract].

OBJECTIVE: To map the disease locus for a congenital cataract family, and detect the disease-causing gene. METHODS: An autosomal dominant congenital cataract family was genotyped by genome wide scan using 382 autosomal microsatellite markers from ABI-MD10. Two-point linkage analysis was carried out by the MLINK program. RESULTS: The disease locus of this family was mapped at 12p11.2-q15. Sequence analysis of a candidate gene-major intrinsic protein (MIP) revealed a novel missense mutation G-->A at the nucleotide 702 in exon 4, which resulted in a substitution of arginine to lysine at codon 233 (p.R233K). CONCLUSION: The mutation G-->A at nt702 in MIP gene was associated with the binocular polymorphic congenital cataract in the family. This transition occurring at the C-terminus of MIP might decrease the stability of the C-end of the protein and impact the function of the protein.

A new locus for inherited nuclear cataract mapped to the long arm of chromosome 1.

PURPOSE: To identify the disease-associated locus in a Chinese family with autosomal-dominant inherited nuclear cataract. METHODS: Genomic DNAs were obtained from 17 family members in a four-generation Chinese family, who had eight members affected with cataract. Exclusive linkage analysis of known candidate inherited cataract loci was performed. A genome-wide scanning was carried out using the ABI PRISM Linkage Mapping set MD-10. For fine mapping, additional markers flanking the most promising region on chromosome 1 were also analyzed. Two-point linkage analysis was performed with the MLINK program of the Linkage software package version 5.1. Haplotype was constructed using Cyrillic version 2.1. RESULTS: After genome-wide scanning, we found significant evidence of linkage for disease loci of nuclear cataract on 1q25-q31 with Z(max)=3.21 at marker D1S3470. Haplotype analysis and recombination events defined a critical interval spanning 4 cM between markers D1S222 and D1S2823 at the long arm of chromosome 1. CONCLUSIONS: We identified a new locus for autosomal dominant inherited nuclear cataract on chromosome 1q in a Chinese family.

[TGFBI gene mutation analysis in a Chinese family with Thiel-Behnke corneal dystrophy].

OBJECTIVE: To identify the gene mutation in autosomal dominant Thiel-Behnke corneal dystrophy affecting a five-generation Chinese family. To study the TGFBI gene mutation in Chinese patients with Thiel-Behnke corneal dystrophy by molecular genetic analysis. METHODS: Ophthalmologic examinations were performed in 10 patients and two normal family members in an autosomal dominant Thiel-Behnke corneal dystrophy family. Five ml peripheral blood was collected and Genomic DNA was extracted using salt fractionation. The exons 4, 7, 8, 11 and 12 of the TGFBI gene were amplified by PCR and mutation analysis was performed by direct sequencing. RESULTS: Mutation analysis of the exons 4, 7, 8, 11 and 12 of the TGFBI gene identified a G-->A missense mutation in the exon 12 by bidirectional sequencing. This mutation resulted in a substitution of glutamine for arginine at amino acid 555 (R555Q) of the protein. This mutation existed in all of the patients, but not in unaffected individuals. CONCLUSION: Thiel-Behnke corneal dystrophy in this family is caused by R555Q mutation of the TGFBI gene, the phenotypes of this corneal dystrophy are closely correlated with TGFBI mutation.

[A research on TGFBI gene mutations in Chinese families with corneal dystrophies].

OBJECTIVE: To identify what kind of TGFBI gene mutation happening to Chinese patients with corneal dystrophies. METHODS: Three Chinese families with stromal corneal dystrophies and one Chinese family with Thiel-Behnke corneal dystrophies were studied, of whom three were Han race and another was Mongolia race in China. All members of families were examined clinically and their genomic DNAs were extracted from blood leukocytes. Thirteen exons in TGFBI gene were amplified by polymerase chain reaction (PCR) and directly sequenced for molecular analysis. RESULTS: Mutations in TGFBI gene were detected from all the patients with corneal dystrophy, but not found in normal subjects of families. The mutation R555W was found and identified from the family with granular corneal dystrophy; R555Q from the family with Thiel-Behnke corneal dystrophy; and R124H from the other two families with Avellino corneal dystrophy. CONCLUSION: The above study results show that the amino acids R124 and R555, if their genetic codes result from the mutations, play an important role in the pathogenesis of autosomal dominant corneal dystrophy of Chinese patients, and the molecular genetic analysis can improve the accuracy of diagnosing corneal dystrophy. In China, the mutation R555Q found in the family with Thiel-Behnke corneal dystrophy is reported for the first time.

[Autosomal dominant congenital golden crystal nuclear cataract caused by a missense mutation in gammaD crystallin gene (CRYGD) in a Chinese family].

OBJECTIVE: To identify genetic defects associated with autosomal dominant congenital golden crystal nuclear cataract (ADCC) in a Chinese pedigree of northern China. METHODS: Clinical data were collected and the lens changes of the affected members in this family were recorded by slit lamp photography. Genomic DNA was obtained from blood leucocytes. Linkage analyses was conducted using polymorphisms of 21 microsatellite markers and mutational analyses of candidate genes was studied by direct sequencing. RESULTS: The maximum LOD score (1.505 at recombination fraction theta = 0.00) was obtained at markers D2S1782, D2S1384 and D2S1385 near the gamma-crystallin gene (CRYG) cluster within 2q33 - q35. Sequencing analysis of the coding regions of the CRYGA. B, C, and D genes showed that the there was a heterozygous C-->A transversion at position 109 (R36S) in exon 2 of CRYGD gene, which was co-segregated with the affected members. CONCLUSIONS: R36S mutation in CRYGD gene results in an ADCC phenotype that is different from previous reports. This finding indicates that the presence of phenotypic heterogeneity of cataract, especially in different races. This is the first report of congenital cataract caused by R36S mutation in CRYGD gene.

[Mutation analysis of FOXL2 in Chinese patients with blepharophimosis-ptosis-epicanthus inversus syndrome].

OBJECTIVE: To identify the genetic mutation in two Chinese families and 6 sporadic patients with belpharophimosis-ptosis-epicanthus inversus syndrome (BPES). METHODS: Polymorphisms of 5 satellite markers on 3q were analyzed and linkage analysis was performed using linkage software (MLINK) in all cases of two families. FOXL2 gene fragments were amplified by PCR and mutation was determined by sequencing DNA fragments in all patients. RESULTS: The BPES locus in the pedigrees was mapped to 3q23, a 9.88 cM interval between markers D3S3696 and D3S1744. The maximum lod scores were 2.11 (theta = 0.00) at D3S1549 and D3S3586 and 1.51 (theta = 0.00) at D3S1764. By direct sequencing FOXL2 gene, two sporadic cases had a 30-bp in frame duplication 909 - 938 dup 30 and one sporadic case showed a nucleotide insertion 1041 - 1042 ins C. However, it was unable to find any causal mutation of FOXL2 in two families with BPES. CONCLUSIONS: The gene responsible for BPES in two Chinese families was linked to D3S1549, D3S3586 and D3S1764. This is the first reported mutations of FOXL2 (909 - 938 dup 30 and 1041 - 1042 ins C) in Chinese sporadic cases. One of the mutations, in-frame 30-bp duplication (909 - 938 dup 30), is one of the most common mutation hotspots in the coding region of FOXL2. In BPES families without FOXL2 mutation, it cannot be excluded that the disorder is caused by a position effect in the surrounding region of FOXL2 gene or by other genes located at 3q23.

A new congenital nuclear cataract caused by a missense mutation in the gammaD-crystallin gene (CRYGD) in a Chinese family.

PURPOSE: To identify genetic defects associated with nuclear golden crystal autosomal dominant congenital cataract (ADCC) in a Chinese pedigree in the north of China. METHODS: Clinical data were collected and the phenotype of the affected members in this family was recorded by slit lamp photography. Genomic DNA was isolated from peripheral blood. Linkage analyses excluded all known loci except that in 2q33-q35. Mutation analysis of CRYGs was carried by direct sequencing of the PCR products. RESULTS: Sequencing of the coding regions of CRYGA, CRYGB, CRYGC, and CRYGD showed the presence of a heterozygous C>A transversion at nt109 of the coding sequence (R36S) in exon 2 of CRYGD, which co-segregated with the affected members. CONCLUSIONS: The R36S mutation in CRYGD identified in this Chinese family caused a nuclear golden crystal cataract phenotype not described before. This finding is an additional indication that there may be phenotypic heterogeneity of cataract, especially in different races.

[Autosomal dominant congenital nuclear cataract caused by a deletion mutation in the beta A1-crystallin gene].

OBJECTIVE: To identify the genetic defect causing automosal dominant congenital cataracts (ADCC) with nuclear opacities in a Chinese pedigree. METHODS: Linkage analysis was carried out with the short tandem repeat polymorphisms flanking the candidate genes. Mutation analysis of the candidate gene in the critical region was performed to detect the potential mutation. RESULTS: The cataract locus in this pedigree was mapped to 17q11.1-12, an 11.78 cM interval between markers D17S933 and D17S 1288. By means of sequencing the candiate gene, betaA1-crystallin (CRYBA1), a deletion mutation DeltaG91 in exon 4 was detected. This change cosegregated with the patients in the family but was not found in 50 normal unrelated individuals. CONCLUSION: It is a deletion mutation DeltaG91 of CRYBA1 gene that causes autosomal dominant congenital nuclear cataract. This is the first report of an autosomal dominant congenital nuclear cataract caused by the mutation in this gene.

[Gene mapping of a pedigree with autosomal dominant congenital cataract].

OBJECTIVE: To map the gene for autosomal dominant congenital cataract (ADCC) in a Chinese family. METHODS: Blood samples were collected from 14 members of this family. Linkage analysis was carried out using short tandem repeat polymorphism (STRP) in close proximity to genes and loci previously reported involving in human cataract. Two-point linkage analysis lod scores were calculated. RESULTS: The mutation gene locus in this pedigree was mapped to 17q, an 11.78-cM interval between markers D17S1288 and D17S933. Significant positive maximum LOD scores (Z(max)) at recombination fraction (theta) 0, were obtained for markers D17S805 (Z(max) = 2.03), D17S1294 (Z(max) = 2.49), and D17S1293 (Z(max) = 2.22). CONCLUSIONS: The mutation gene in this ADCC pedigree is located at chromosome 17q. This is the first report of an autosomal dominant congenital nuclear cataracts located at this locus. This result will be helpful for further studying of the pathogenesis of cataract.

A deletion mutation in the betaA1/A3 crystallin gene ( CRYBA1/A3) is associated with autosomal dominant congenital nuclear cataract in a Chinese family.

Congenital cataracts are an important cause of blindness worldwide. In a family of Chinese descent, a dominant congenital nuclear cataract locus was mapped to chromosome 17q11.1-12. The maximum LOD score, 2.49, at recombination fraction 0, was obtained for marker D17S1294. The results of both linkage and haplotype analyses defined a disease-gene to an 11.78-cM region harboring the gene coding for betaA1/A3 crystallin ( CRYBA1/A3). Mutation analysis of the CRYBA1/A3 gene identified a 3-bp deletion in exon 4, which cosegregated with the disease risk in this family and was not observed in 100 normal chromosomes. This mutation resulted in the deletion of a highly conserved glycine at codon 91 (DeltaG91) and could be associated with an incorrect folding of betaA1/A3 crystallin. It highlights the physiological importance of crystallin and supports the role of CRYBA1/A3 in human cataracts formation.