Phenotypic variability in Meesmann's dystrophy: clinical review of the literature and presentation of a family genetically identical to the original family.

Purpose: To describe the phenotypic variability in Meesmann's microcystic dystrophy of the corneal epithelium based on a review of the literature and the presentation of a Danish family.
Methods: We carried out a clinical examination of the family and genetic sequencing of DNA.
Results: Subjective symptoms often include blurred vision and ocular irritation. Typical cases may be entirely free of complaints. Intermittent pain episodes, such as occur in recurrent erosion syndrome, are not the rule. Genetic sequencing indicated a familial relationship with the originally described Meesmann family. Clinical variability was similar. Approximately 85% of cases showed microcysts in the entire epithelium. The remaining 15% demonstrated variants with microcysts in the upper or lower part of the cornea, or in the central or peripheral cornea, as well as subepithelial opacities.
Conclusions: Meesmann's dystrophy occurs worldwide. The largest family described is the original German one, now supplemented with a Danish branch. Despite the presence of an identical genetic defect, the clinical phenotype varies. This suggests that non-KRT12-related mechanisms are responsible for the variation.