Biomedical subjects

Vivek S Yellore

Publications and source records attributed to Vivek S Yellore.

14 recordsLinked to original sources

PubMed2006

Unilateral lattice corneal dystrophy associated with the novel His572del mutation in the TGFBI gene.

PURPOSE: To report a novel mutation in the TGFBI gene, c.1761_1763del (p.His572del), associated with a unilateral variant of lattice corneal dystrophy (LCD). METHODS: A 63-year-old man presenting with the complaint of decreased vision in one eye was noted to have a unilateral lattice corneal dystrophy. Examination of the patient's wife and two sons, ages 20 and 27 years old, failed to reveal the presence of any corneal opacities. Following the collection of DNA from the patient and his family members, the TGFBI gene was screened for mutations previously associated with lattice corneal dystrophy and any novel coding region changes. RESULTS: In the affected patient, none of the mutations previously associated with the classic and variant forms of LCD were identified. However, a novel mutation, c.1761_1763del (p.His572del), was identified in exon 13 of TGFBI in the patient and his sons. This mutation was not identified in the patient's wife or in 200 control chromosomes. CONCLUSIONS: The novel TGFBI gene mutation (p.His572del) is associated with a unilateral, late-onset variant of lattice corneal dystrophy. This case highlights the utility of molecular genetic analysis in differentiating corneal dystrophies associated with an atypical phenotype from nondystrophic conditions.

Adult↗

PubMed2006

No pathogenic mutations identified in the TGFBI gene in polymorphic corneal amyloid deposition.

PURPOSE: To determine whether primary, polymorphic, corneal amyloid deposition is associated with a mutation of the TGFBI gene. METHODS: Interventional case series of 8 patients. Slit lamp examination of all patients and photodocumentation of 5 patients were performed. Genomic DNA was isolated from buccal mucosal swabs obtained from all patients and all 17 exons of the TGFBI gene were amplified and sequenced. RESULTS: Multiple polymorphic, refractile deposits were noted throughout the central corneal stroma in all patients. The deposits appeared gray-white on direct illumination and translucent on retroillumination, characteristic of amyloid. In 2 patients, linear, branching opacities, reminiscent of lattice corneal dystrophy, were identified. Histopathologic examination confirmed the presence of stromal amyloid in the cornea of 1 patient who required corneal transplantation for pseudophakic corneal edema. Screening of the entire coding region of the TGFBI gene revealed 4 previously described synonymous substitutions, Leu217Leu, Val327Val, Leu472Leu, and Phe540Phe. A previously unreported missense change, Asp299Asn, was identified in one affected patient but not in her affected sister. No pathogenic mutations, including the Ala546Asp missense mutation previously associated with polymorphic corneal amyloidosis, were identified in any of the patients. CONCLUSIONS: TGFBI gene mutations were not identified in a series of patients with polymorphic corneal amyloid deposition. As bilateral, discrete stromal amyloid deposits may be dystrophic or degenerative, differentiation between these phenotypically similar conditions is facilitated with the use of molecular genetic analysis.

Aged↗

PubMed2006

No VSX1 gene mutations associated with keratoconus.

PURPOSE: To determine whether mutations of the VSX1 gene play a pathogenetic role in the development of keratoconus (KTCN). METHODS: DNA extraction, PCR amplification, and direct sequencing of the VSX1 gene were performed in 100 unrelated patients with diagnoses of clinical and topographic features of KTCN. RESULTS: Of the four previously identified presumed pathogenic mutations in the VSX1 gene (Leu17Pro, Asp144Glu, Leu159Met, and Arg166Trp), only Asp144Glu was identified in a single affected patient. Two novel single nucleotide polymorphisms (SNPs), both resulting in synonymous substitutions, were identified: c.53G>T (Ser6Ser) in four affected patients and c.209G>T (Pro58Pro) in two affected patients. Two previously reported SNPs were also identified: c.426C>A (Arg131Ser) in one affected patient and c.581A>G (Ala182Ala) in 51 of the 100 affected patients. CONCLUSIONS: Only one of the presumed pathogenic mutations in the VSX1 gene, Asp144Glu, was identified in a single member of the cohort of affected patients. However, as previously demonstrated, Asp144Glu is a non-disease-causing polymorphism. The absence of pathogenic mutations in the VSX1 gene in a large number of unrelated KTCN patients indicates that other genetic factors are involved in the development of this disorder.

Adolescent↗

PubMed2006

No pathogenic mutations identified in the COL8A1 and COL8A2 genes in familial Fuchs corneal dystrophy.

PURPOSE: To investigate the genetic basis of late-onset, familial Fuchs endothelial corneal dystrophy (FECD) through screening of the COL8A1 and COL8A2 genes, in which mutations have been associated with both early and late-onset, familial and sporadic FECD. METHODS: DNA extraction, PCR amplification, and direct sequencing of the COL8A1 and COL8A2 genes was performed in affected and unaffected members of 15 unrelated families with two or more members with late-onset FECD. RESULTS: Screening of the COL8A1 gene did not reveal sequence variants in any affected individuals from the 15 FECD families. In the COL8A2 gene, the previously identified mutations presumed to play a pathogenic role in cases of familial FECD (Arg155Gln, Leu450Trp, and Gln455Lys) were not discovered in any of the affected patients. A mutation previously considered causative of FECD (Arg434His) was shown not to segregate with the disease in the one family in which it was identified. Two previously identified single-nucleotide polymorphisms (SNPs), Pro575Leu and Pro586Pro, were identified in a single affected individual and three affected individuals (two families), respectively. CONCLUSIONS: The Arg434His mutation in the COL8A2 gene, previously associated with FECD, has been shown not to segregate with the disease phenotype, and thus may not be considered a disease-causing mutation. The absence of pathogenic mutations identified in the COL8A1 or COL8A2 genes in affected members of 15 pedigrees with familial FECD indicates that other genetic factors are involved in the development of this autosomal dominant corneal dystrophy.

Adult↗

PubMed2005

Analysis of fifteen positional candidate genes for Schnyder crystalline corneal dystrophy.

PURPOSE: To identify the genetic basis of Schnyder crystalline corneal dystrophy (SCCD) through screening of positional candidate genes in affected patients. METHODS: Mutation screening of fifteen genes (CORT, CLSTN1, CTNNBIP1, DFFA, ENO1, GPR157, H6PD, KIF1B, LOC440559, LZIC, MGC4399, PEX14, PGD, PIK3CD, and SSB1) that lie within the candidate gene region for SCCD was performed in members of two families affected with SCCD. RESULTS: No presumed disease-causing mutations were identified in affected patients. Seventeen previously described single nucleotide polymorphisms (SNPs) were identified in eight of the candidate genes. Novel SNPs were identified in both affected and unaffected individuals in GPR157 (c.795C>T [Arg218Leu]; c.811C>T [Ala223Val]), MGC4399 (c.1024G>C [Leu277Leu]), and H6PD (c.754A>C [Asp151Ala]). CONCLUSIONS: No pathogenic mutations were identified in fifteen positional candidate genes in two families with SCCD. As the candidate gene region in each SCCD family previously examined with haplotype analysis has been mapped to the same chromosomal region, the absence of pathogenic mutations in these positional candidates in the families we examined reduces the number of remaining positional candidate genes by half, and the number of remaining candidate genes with a known gene function by two-thirds. We anticipate that screening of the remaining positional candidate genes will lead to the identification of the genetic basis of SCCD.

Adolescent↗

PubMed2005

A unique corneal dystrophy of Bowman's layer and stroma associated with the Gly623Asp mutation in the transforming growth factor beta-induced (TGFBI) gene.

PURPOSE: To report a unique corneal dystrophy characterized by deposits at Bowman's layer and stromal lattice lines associated with the Gly623Asp missense mutation in the transforming growth factor beta-induced (TGFBI) gene. DESIGN: Experimental study. PARTICIPANTS AND CONTROLS: The proband, 3 affected siblings, 4 unaffected relatives, and 100 control individuals. METHODS: Slit-lamp examination, photographic documentation, and isolation of genomic DNA from buccal mucosal swabs obtained from each family member examined. Exons 4 and 11 to 14 of the TGFBI gene were amplified and sequenced in these family members and in control individuals. MAIN OUTCOME MEASURES: Clinical characteristics of corneal opacification in affected patients and presence of coding region changes in the TGFBI gene. RESULTS: Significant phenotypic variability, including polymorphic Bowman's layer opacities and stromal lattice lines, was noted in the 4 affected siblings who were examined. Screening of TGFBI exon 14 in the proband, 3 affected siblings, and a 19-year-old unaffected relative revealed a missense change, Gly623Asp, that was absent in the other 3 unaffected relatives screened and in 200 control chromosomes. CONCLUSIONS: We report a novel corneal dystrophy phenotype secondary to the Gly623Asp mutation in the TGFBI gene that is associated with clinical features of both lattice corneal dystrophy and a Bowman's layer dystrophy. The presence of clinical features considered atypical for a TGFBI-associated dystrophy in this pedigree, as well as the wide range of phenotypic expressions of the Gly623Asp mutation in affected members, underscore the clinical utility of molecular genetic analysis in the diagnosis of suspected corneal dystrophies.

Adult↗

PubMed2005

Lattice dystrophy-like localized amyloidosis of the cornea secondary to trichiasis.

PURPOSE: To report a case of stellate and branching linear corneal stromal amyloid deposits secondary to trichiasis and the use of molecular genetic analysis to exclude lattice corneal dystrophy. METHODS: Case report and review of the literature. A 30-year-old man with a history of chronic ocular irritation was found to have distichiasis, epiblepharon, and unilateral corneal amyloidosis indistinguishable from lattice corneal dystrophy. Screening of the TGFBI gene was performed to rule out a previously reported mutation associated with lattice corneal dystrophy. RESULT: A corneal biopsy performed before presentation to the authors confirmed the presence of corneal amyloidosis. Screening of exons 4, 11, 12, and 14 in the TGFBI gene identified 2 previously reported polymorphisms, Leu472Leu and Phe540Phe, but no other coding region changes. CONCLUSION: Corneal stromal amyloidosis clinically resembling lattice corneal dystrophy may be associated with trichiasis. The exclusion of a TGFBI-associated corneal dystrophy in this case, leaving trichiasis as the most likely cause of the corneal amyloid deposition, demonstrates the utility of molecular genetic analysis in confirming or refuting a presumptive clinical diagnosis.

Adult↗

PubMed2005

Candidate gene screening for posterior polymorphous dystrophy.

PURPOSE: To perform candidate gene screening for posterior polymorphous corneal dystrophy (PPCD). The initial 3 genes chosen, ID1, BCL2L1, and VSX1, lie within the region on chromosome 20 to which the PPCD gene has been linked, and mutations in VSX1 have previously been identified in patients with PPCD. METHODS: DNA extraction, PCR amplification, and direct sequencing of the VSX1, BCL2L1, and ID1 genes were performed in 14 affected patients (12 families) as well as in unaffected family members and healthy control subjects. RESULTS: No coding region mutations in the BCL2L1 or ID1 genes were identified in affected patients. In the VSX1 gene, the previously identified Gly160Asp missense change was not present in any of our 12 probands, and the Asp144Glu mutation was identified in 1 affected patient as well as 1 unaffected control individual. Additionally, 2 synonymous substitutions were identified, Ala182Ala (8 affected patients from 8 families) and Gly239Gly (1 affected patient and 1 unaffected patient from the same family). In the ID1 gene, the synonymous substitution Gly216Gly was observed in 2 affected patients (2 families) who also demonstrated a single nucleotide change in both the 5'UTR (2129T>C) and 3'UTR (3267A>G). Another 5'UTR change, 2177T>C, was identified in 1 affected patient and his unaffected parent, both of whom also demonstrated the 2129T>C and 3267A>G changes. CONCLUSIONS: None of the 12 probands with PPCD demonstrated the previously described Gly160Asp mutation within the VSX1 gene. The Asp144Glu missense change, present in an affected patient as well as an unaffected control individual, appears to be a rare polymorphism, not a disease-causing mutation. No coding region changes were identified in the ID1 or BCL2L1 genes. Therefore, although we report a number of novel polymorphisms in the VSX1 and ID1 genes, the failure to identify any sequence variants that sort with the disease phenotype suggests that other genetic factors are involved in PPCD.

Corneal Dystrophies, Hereditary↗

PubMed2005

No pathogenic mutations identified in the COL8A2 gene or four positional candidate genes in patients with posterior polymorphous corneal dystrophy.

PURPOSE: To identify the genetic basis of posterior polymorphous corneal dystrophy (PPCD) through screening of four positional candidate genes and the COL8A2 gene, in which a presumed pathogenic mutation has previously been identified in affected patients. METHODS: DNA extraction, PCR amplification, and direct sequencing of the COL8A2, BFSP1, CST3, MMP9, and SLPI genes were performed in 14 unrelated, affected patients and in unaffected family members. RESULTS: In the COL8A2 gene, the previously identified, presumed pathogenic mutation (Gln455Lys) was not discovered in any of the affected patients. A missense mutation, Thr502Met, was identified in 2 of the 14 affected probands, although it was not considered to be pathogenic, as it has been identified in unaffected individuals. Although several novel and previously identified single nucleotide polymorphisms producing synonymous and missense amino acid substitutions were identified in the COL8A2, BFSP1, CST3, MMP9, and SLPI genes, no presumed pathogenic sequence variants were found. CONCLUSIONS: No pathogenic mutations were identified in the COL8A2 gene or in several positional candidate genes in a series of patients with PPCD, indicating that other genetic factors are involved in the development of this autosomal dominant corneal dystrophy.

Collagen Type VIII↗

PubMed2004

Novel mutations in the carbohydrate sulfotransferase gene (CHST6) in American patients with macular corneal dystrophy.

PURPOSE: To further characterize the mutations within the CHST6 gene responsible for causing macular corneal dystrophy in a cohort of affected patients from the United States. DESIGN: Experimental study. METHODS: Genomic DNA was extracted from buccal epithelium of 16 affected patients (14 families), 17 unaffected relatives, and 127 controls, followed by polymerase chain reaction amplification and direct sequencing of the CHST6 coding region. Subtyping of affected patients into type I and II macular corneal dystrophy was performed by measuring antigenic keratan sulfate (AgKS) serum levels. Haplotype analysis was performed in families that demonstrated common mutations. RESULTS: CHST6 coding region analysis in 10 patients identified as having type I macular corneal dystrophy revealed 10 sequence changes: eight missense mutations, four of which are novel (Met104Val, Tyr110Cys, Gln122Pro, and Leu276Pro) and four of which have been reported previously (Ser51Leu, Pro72Ser, Cys102Gly, and Leu200Arg); one novel homozygous nonsense mutation in two patients from a single family (c. 1683C>T, Gln331X); and one frameshift mutation in a heterozygous state in a single patient (c.1744_1751dupGTGCGCTG). Mutation analysis in the four patients identified as having type II macular corneal dystrophy (serum samples were not obtained from two affected patients) revealed three patients heterozygous for either the c.923G>C, c.969C>A, or c.1519T>C sequence changes. The fourth patient was compound heterozygous for c.969C>A and c.1291T>G. None of these changes was observed in 127 control individuals. Haplotype analysis using microsatellite markers flanking the CHST6 gene did not reveal a common founder for the Leu200Arg (1291T>G) missense mutation, present in five families, identifying this position as a mutation hot-spot. CONCLUSIONS: A variety of previously unreported mutations in the coding region of the CHST6 gene are associated with type I macular corneal dystrophy in a cohort of patients from the United States.

Adult↗

PubMed2004

Anterior basement membrane corneal dystrophy and pseudo-unilateral lattice corneal dystrophy in a patient with recurrent corneal erosions.

PURPOSE: To report the utility of genetic testing in the diagnosis and management of patients with suspected corneal dystrophies. DESIGN: Case report. METHODS: A 58-year-old man with a history of recurrent corneal erosions was diagnosed with bilateral anterior basement membrane dystrophy and unilateral lattice corneal dystrophy. All 17 exons of the TGFBI gene were screened for mutations previously associated with lattice corneal dystrophy as well as novel coding region changes. RESULTS: No mutations were found in the 17 exons of the TGFBI gene. A nucleotide change in exon 6 (651C>G) did not result in a change in the encoded amino acid (Leu217Leu). CONCLUSIONS: In cases of suspected TGFBI corneal dystrophies, genetic testing is a useful tool to confirm the clinical diagnosis. In this case of suspected unilateral lattice corneal dystrophy, screening of the TGFBI gene ruled out the diagnosis, raising the possibility that the corneal changes were related to the coexistent anterior basement membrane dystrophy.

Basement Membrane↗

PubMed2004

Lattice corneal dystrophy associated with the Ala546Asp and Pro551Gln missense changes in the TGFBI gene.

PURPOSE: To report a phenotypic variant of lattice corneal dystrophy associated with two missense changes, Ala546Asp and Pro551Gln, in the transforming growth factor-beta-induced gene (TGFBI). DESIGN: Experimental study. METHODS: Genomic DNA was obtained from the proband as well as affected and unaffected family members. Exons 4, 11, 12, and 14 of the TGFBI gene were amplified and sequenced. Additionally, a corneal button excised from the proband was examined by light and transmission electron microscopy. Haplotype analysis was performed on the proband's family and members of a previously identified pedigree with the same TGFBI gene missense changes. RESULTS: Bilateral, symmetric, radially arranged, branching refractile lines within and surrounding an area of central anterior stromal haze were noted in the proband. Multiple polymorphic, refractile deposits were noted in the mid and posterior stroma in both the proband and her daughter. Light and electron microscopic analyses demonstrated amyloid and excluded the presence of deposits characteristic of granular corneal dystrophy. Screening of TGFBI exon 12 in the proband and her affected daughter revealed two missense changes, Ala546Asp and Pro551Gln (both absent in 250 control chromosomes). Haplotype analysis suggested that the mutations in this family and in a previously identified pedigree reflect a founder effect, rather than an independent occurrence. CONCLUSIONS: We present a phenotypic variant of lattice corneal dystrophy associated with the Ala546Asp and Pro551Gln missense changes in exon 12 of the TGFBI gene. A common ancestor appears to account for the missense mutations observed in this pedigree and in a previously reported family.

Adult↗

PubMed2004

The usefulness of buccal swabs for mutation screening in patients with suspected corneal dystrophies.

PURPOSE: To make ophthalmologists aware of the usefulness of buccal swabs for the collection of cells from which DNA may be extracted to be used in genetic screening of patients with known or suspected inherited ocular disorders, such as corneal dystrophies. DESIGN: Illustrative interventional case report. METHODS: Buccal epithelial swabs were collected from a 3-year-old boy with a presumed corneal dystrophy and his unaffected parents. Swabs were mailed to a laboratory where transforming growth factor-beta-induced gene (TGFBI) mutation screening was performed. MAIN OUTCOME MEASURES: Results of sequencing TGFBI exons 4 and 12. RESULTS: Transforming growth factor-beta-induced gene mutation screening in a child with bilateral anterior corneal stromal opacification revealed the following changes in exon 12: 1667T>C (Phe540Phe), 1684C>A (Ala546Asp), and 1699C>A (Pro551Gln). The child's father demonstrated the 1667T>C nucleotide substitution, but neither parent demonstrated the 1684T>C or the 1699C>A changes. CONCLUSIONS: Buccal swabs provide the ophthalmologist with a simple, inexpensive means of collecting and transporting cells from which DNA may be extracted to be used to either confirm or refute diagnoses solely on the basis of clinical features. In this case, the diagnosis of an atypical variant of lattice corneal dystrophy was made on the basis of the identification of previously reported mutations in TGFBI.

Child, Preschool↗

PubMed2003

Atypical vortex pattern of corneal deposits in granular corneal dystrophy.

PURPOSE: To report the appearance of an unusual vortex pattern of corneal deposits in two patients with the R555W mutation in the transforming growth factor beta-induced gene (TGFB1) associated with granular corneal dystrophy. METHODS: DNA from affected patients and unaffected relatives was isolated from buccal swabs, and TGFB1 mutation screening was performed. RESULTS: The proband and an affected daughter demonstrated rays of deposits emanating from a point in the inferior cornea of each eye in a "sea fan" or vortex pattern. Screening all 17 exons of TGFB1 in the proband identified a single missense mutation (C1710T) in exon 12, consistent with the diagnosis of granular corneal dystrophy. The identical mutation was identified in the affected daughter. CONCLUSIONS: In spite of the strict phenotype-genotype correlation reported for the TGFB1-associated corneal dystrophies, atypical clinical findings may be produced by previously identified, conserved mutations.

Adult↗