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A novel mutation I522N within the TGFBI gene caused lattice corneal dystrophy I.

ABSTRACT: PURPOSE: To identify mutations within the TGFBI gene in a Chinese family with lattice corneal dystrophy type I (LCD I). METHODS: Genomic DNA of three affected, four unaffected family members and 50 normal individuals was extracted from peripheral leukocytes. All exons of TGFBI were amplified by polymerase chain reaction (PCR) methods and direct sequencing was carried out for mutation analysis. RESULTS: A missense mutation (1565T-->A) in exon12 of TGFBI led to an amino acid substitution I522N in the TGFB-induced protein in all affected family members, but the mutation was not detected in normal subjects of the family and control individuals. CONCLUSIONS: We conclude that the novel mutation I522N causes lattice corneal dystrophy type I in the studied family. This is the first report of the I522N mutation within TGFBI in LCD I worldwide.

SUBMITTER: Zhang C

PROVIDER: S-EPMC2786890 | biostudies-literature | 2009

REPOSITORIES: biostudies-literature

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A novel mutation I522N within the TGFBI gene caused lattice corneal dystrophy I.

Zhang Chunmei C Zeng Guang G Lin Hui H Li Dandan D Zhao Liming L Zhou Nan N Qi Yanhua Y

Molecular vision 20091128

<h4>Purpose</h4>To identify mutations within the TGFBI gene in a Chinese family with lattice corneal dystrophy type I (LCD I).<h4>Methods</h4>Genomic DNA of three affected, four unaffected family members and 50 normal individuals was extracted from peripheral leukocytes. All exons of TGFBI were amplified by polymerase chain reaction (PCR) methods and direct sequencing was carried out for mutation analysis.<h4>Results</h4>A missense mutation (1565T-->A) in exon12 of TGFBI led to an amino acid sub ...[more]

PMID: 19956413

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Project description:PURPOSE: To report the clinical, ophthalmic, and genetic characteristics for lattice corneal dystrophy type I (LCDI) in a Chilean family. METHODS: Six affected family members were examined clinically including visual acuity, color cornea photography, applanation tonography, and fundoscopy. Genomic DNA was extracted from peripheral leukocytes from six affected and three unaffected members of a family with lattice corneal dystrophy type I. Exon 4 of the transforming growth factor-induced gene (TGFBI) was screened for the most frequent mutation, R124C, in the proband by sequencing. We also designed a rapid polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method to analyze the same mutation, amplifying exon 4 and digesting with PstI restriction enzyme. Using this strategy, we analyzed the mutation in six affected and three healthy family members. RESULTS: Three generations of family members were positively diagnosed with lattice corneal dystrophy. Six participants demonstrated LCD1 in both eyes, most of whom were symmetric. Age at onset of symptoms was variable (3-42 years old). Moreover, in this family, the age of onset of the disease decreased in succeeding generations, which could be interpreted as anticipation. Visual acuity varied from 1.0 to 0.13. Two patients, ages 69 and 44 years old, demonstrated a degree of severity "Bad" according to best-corrected vision and corneal commitment. The exon 4 sequence of TGFBI of the proband exhibits the heterozygous single-nucleotide mutation, C417T, leading to amino acid substitution (R124C) in the encoded TGF-induced protein. Using PCR-RFLP, we confirmed the heterozygous mutation in six affected family members and excluded it in three healthy members. CONCLUSIONS: The R124C mutation in TGFBI cosegregated with LCD type I in the investigated family. This is the first report of a molecular analysis of LCD type I in Chilean patients. The early onset affected persons in the fourth generation raises the possibility of anticipation.

Project description:BackgroundReis-Bücklers corneal dystrophy (RBCD) was consistently reported as a corneal dystrophy only affected Bowman's layer and superficial corneal stroma, and superficial keratectomy was a recommendation surgery for treatment in literatures. The study reported new histopathological and ultrastructural findings in RBCD caused by the Arg124Leu mutation of transforming growth factor induced (TGFBI) gene in a four-generation Chinese pedigree.MethodsSubjects including eight patients and seven unaffected family members received slit-lamp biomicroscopy and photography. DNA was obtained from all subjects, and exons 4 and 11 to 14 of TGFBI gene were analyzed by polymerase chain reaction and the products were sequenced. Anterior segment optical coherence tomography (AS OCT) and in vivo confocal microscopy were conducted for ten eyes of five patients. Based on the results of AS OCT and in vivo confocal microscopy, deep anterior lamellar keratoplasty (DLKP) using cryopreserved donor cornea was applied for four eyes of four patients. Four lamellar dystrophic corneal buttons were studied by light and transmission electron microscopy, and TGFBI immunohistochemistry.ResultsEight patients had typical clinical manifestations of RBCD presenting recurrent painful corneal erosion starting in their early first decades, along with age-dependent progressive geographic corneal opacities. TGFBI sequencing revealed a heterozygous mutation, Arg124Leu in all eight patients. Anterior segment optical coherence tomography and in vivo confocal microscopy showed the dystrophic deposits involved not only in subepithelial and superficial stroma, but also in mid- or posterior stroma in four examined advanced eyes. Light microscopy showed Bowman's layer was absent, replaced by abnormal deposits stain bright red with Masson's trichrome. In superficial cornea, the deposits stacked and produced three to five continuous bands parallel to the corneal collagen lamellae. In mid- to posterior stroma, numerous granular or dot- like aggregates were heavily scattered, and most of them presented around the nuclei of stromal keratocytes. Transmission electron microscopy revealed the multiple electron-dense rod-shaped deposits aggregated and formed a characteristic pattern of three to five continuous bands in superficial cornea, which were similar to those seen under light microscopy. In mid- to posterior stroma, clusters of rod-shaped bodies were scattered extracellular or intracellular of the stromal keratocytes between the stromal lamellae suggesting the close relationship between mutated proteins and keratocyte.ConclusionsThe study offer evidences indicating DLKP is a viable treatment option for advanced RBCD to avoid recurrence, and the mutated TGFBIp in dystrophic corneas are of keratocytes origin.

Dataset Information

A novel mutation I522N within the TGFBI gene caused lattice corneal dystrophy I.

Publications

A novel mutation I522N within the TGFBI gene caused lattice corneal dystrophy I.

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