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.

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.

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.

An unusual clinical phenotype of Avellino corneal dystrophy associated with an Arg124His beta iG-H3 mutation in an African-American woman.

PURPOSE: To describe the clinical features, histologic changes, and genetic analysis of Avellino corneal dystrophy in an African-American woman. DESIGN: Interventional case report. METHODS: A 79-year-old African-American woman with corneal deposits consistent with Avellino corneal dystrophy was studied with histologic and genetic analysis. RESULTS: The patient had multiple crumb-like opacities in the anterior stroma of both eyes. Deep to these lesions were numerous faint, stellate lattice lesions. Corneal scraping confirmed the presence of Masson trichrome and Congo red positive subepithelial deposits. Genetic analysis revealed a heterozygous CGC/CAC change in exon 4 of the beta iG-H3 gene, resulting in an arginine to histidine substitution at codon 124. CONCLUSIONS: This case reveals several novel findings, including surface changes resembling vortex dystrophy and large granular deposits protruding through the anterior corneal surface. This is the first case described in an African-American patient.