Clinical Phenotype of Messmann Corneal Dystrophy With No Mutation in KRT3 and KRT12

Abstract

Purpose: : To report on patients presenting symptoms and signs of Meesmann corneal dystrophy (MCD) but carrying no mutation in both cornea-specific keratin genes (KRT3 and KRT12). MCD is characterized by fragility of the anterior corneal epithelium, which is morphologically manifested by intraepithelial microcysts. The disease is generally benign and affected individuals are usually asymptomatic but some may suffer from recurrent erosions leading to lacrimation and photophobia. At present it is assumed that MCD is caused by mutations in keratin 3 (KRT3) or 12 (KRT12) genes encoding cornea-specific cytoskeletal proteins.

Methods: : Examination of the anterior eye segments was performed by slit lamp biomicroscopy and in vivo confocal microscopy (IVCM) using ConfoScan 3 white light scanning slit confocal microscope (Nidek Technologies, Padova, Italy). Blood genomic DNA served as a template for amplification and bidirectional sequencing of all coding regions of KRT3 and KRT12.

Results: : We report on three patients presented with ocular irritation, tearing and glare, in which MCD was diagnosed clinically on the basis of subjective symptoms and typical appearance of the corneal epithelium. Microcysts within the epithelium characteristic for MCD were visualized with slit-lamp examination and confirmed by in vivo confocal microscopy. In all three patients no mutation in either of the keratin genes was detected.

Conclusions: : Results of our study show that clinical phenotype identical or similar to MCD may be caused by other factors than mutations in keratin 3 (KRT3) or 12 (KRT12) genes The possible novel genetic relations are currently sought.

Keywords: cornea: epithelium • genetics • imaging/image analysis: clinical