Late-onset lattice corneal dystrophy without typical lattice lines caused by a novel mutation in the TGFBI gene.

ABSTRACT

PURPOSE: The aim of this study was to report the clinical, histopathological, and molecular findings in a patient with late-onset lattice corneal dystrophy (LCD) without typical lattice lines and a novel mutation in the TGFBI gene. METHODS: Corneal lesions were visualized by slit-lamp examination and by in vivo confocal microscopy. Histopathological examination was performed on the patient's corneal specimen obtained during a deep anterior lamellar keratoplasty. By using genomic DNA as a template, all coding regions of the TGFBI gene were amplified and directly sequenced. The presence of the mutation was verified using restriction endonuclease digestion. Eight different computational methods and multiple sequence alignments were used to predict the pathogenicity of the novel genetic variant. RESULTS: The corneal phenotype was characterized by the presence within the stroma of round, oval, and short comma-shaped structures with indistinct margins. Lattice lines were not visible. Histopathological study revealed positive Congo red areas of amyloid deposits typical for LCD. A novel heterozygous missense mutation p.Leu565Pro was identified in exon 13 of the TGFBI gene. The amino acid substitution was unambiguously predicted to have a high pathogenic potential. CONCLUSIONS: The mutant codon 565 is located at the C-terminus in the region corresponding to a highly conserved amino acid in the fourth fascilin domain of the TGFBI protein. The novel variant expands the spectrum of TGFBI mutations causing LCD and located in this region. An increased number of known mutations will facilitate future studies of genotype-phenotype correlations and molecular pathogenesis of corneal dystrophies.