[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.

[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 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.

[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.

[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.