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

Coexistence of Meesmann Corneal Dystrophy and a Pseudo-Unilateral Lattice Corneal Dystrophy in a Patient With a Novel Pathogenic Variant in the Keratin K3 Gene: A Case Report

PURPOSE

This study aims to clinically and genetically report a case of coexisting Meesmann corneal dystrophy (MECD) and pseudo-unilateral lattice corneal dystrophy (LCD).

METHODS

Clinical characterization was supported by a complete ophthalmological evaluation, including visual acuity measurement and slit-lamp examination. Molecular diagnosis was performed by whole-exome sequencing analyzing the gelsolin, keratin K3 (KRT3), keratin K12, and transforming growth factor-beta-induced genes.

RESULTS

A 57-year-old woman presented with recurrent corneal erosions over 17 years and visual impairment in both eyes. Ophthalmological evaluation revealed multiple central tiny cysts in the epithelium of both eyes and lattice linear lesions only in the right cornea. In both eyes, a corneal posterior crocodile shagreen degeneration could also be observed. These findings were compatible with a MECD and a unilateral LCD. Molecular analysis identified the novel heterozygous nucleotide substitution c.1492G>A (amino acid change p.Glu498Lys) in the KRT3 gene, in cosegregation with the MECD familial phenotype. However, no genetic evidence supported the unique LCD phenotype observed in the patient.

CONCLUSIONS

To the best of our knowledge, this is the first report of a pseudo-unilateral LCD in a patient with coexistent MECD. Moreover, the genetic analysis showed a novel mutation in the previously MECD-associated gene KRT3.

Classic lattice corneal dystrophy associated with monoclonal gammopathy after exclusion of a TGFBI mutation

PURPOSE

The purpose of this study was to report the association of phenotypic features characteristic of lattice corneal dystrophy (LCD) with a monoclonal gammopathy of undetermined significance (MGUS) after exclusion of a coding region mutation in transforming growth factor beta-induced (TGFBI) gene.

DESIGN

Case report.

METHODS

Slit-lamp examination and collection of DNA for TGFBI screening were performed. A systemic evaluation was also performed to evaluate for conditions associated with systemic amyloidosis.

RESULTS

A 65-year-old man demonstrated bilateral linear branching corneal stromal opacities characteristic of classic LCD. No mutations were found in any of the 17 exons of TGFBI or in the intron-exon boundary regions. Four previously described single nucleotide polymorphisms were identified: c.698C>G (p.Leu217Leu; rs1442), c.1028A>G (p.Val327Val; rs1054124), c.1416C>T (p.Leu472Leu; rs1133170), and c.1667T>C (p.Phe540Phe; rs4669). Serum protein electrophoresis revealed the presence of a monoclonal spike, and based on the results of additional investigations, the patient was diagnosed with MGUS.

CONCLUSIONS

Although the presence of bilateral thin branching lattice lines in the corneal stroma is characteristic of classic LCD, this distinctive phenotype may not be associated with a TGFBI coding region mutation but instead with a myeloproliferative disorder such as MGUS. Therefore, appropriate genetic and serologic testing should be performed in patients with a late-onset LCD phenotype in the absence of a positive family history.

A subset of patients with epithelial basement membrane corneal dystrophy have mutations in TGFBI/BIGH3

Epithelial basement membrane corneal dystrophy (EBMD), also known as Cogan microcystic epithelial dystrophy or map-dot-fingerprint dystrophy, is a common bilateral epithelial dystrophy. Usually, this disease is not considered to be inherited although several families with autosomal dominant inheritance have been described. We report the analysis of two families with an autosomal dominant pattern of inheritance as well as the analysis of single affected individuals; we identified two different point mutations in the TGFBI/BIGH3 genes, genes known to be associated with other corneal dystrophies. This is the first report of a molecular mutation in individuals with EBMD and it increases the spectrum of mutations in the TGFBI/BIGH3 gene. Based on our screening, up to 10% of EBMD patients could have a mutation in this gene.