Lisch corneal dystrophy is genetically distinct from Meesmann corneal dystrophy and maps to xp22.3.

PURPOSE

There is an ongoing discussion whether Lisch corneal dystrophy (band-shaped and whorled microcystic dystrophy of the corneal epithelium) represents a disorder that is different from Meesmann corneal dystrophy. The purpose of this study was to evaluate at the molecular level if Lisch and Meesmann corneal dystrophies are genetically distinct.

METHODS

We examined at the slit lamp a total of 48 members of a family with an aggregation of Lisch corneal dystrophy. Genomic DNA was extracted from leukocytes of the peripheral blood of seven affected and six unaffected members of this family. Mutational hotspots in the cornea-specific keratin genes K3 and K12 were scanned for mutations by single-strand conformation analysis. To test for linkage to the keratin K3 or K12 loci or for X-chromosomal inheritance, six (K3) and four (K12) microsatellite markers each flanking the keratin loci as well as 22 microsatellite markers covering the X-chromosome were typed. Linkage was analyzed using the MLINK and FASTMAP procedures.

RESULTS

A total of 19 trait carriers were identified in six generations of the family. No hereditary transmission from father to son was observed. Linkage was excluded for the keratin K3 and K12 genes. Furthermore, single-strand conformation analysis detected no mutations in these genes. Multipoint linkage analysis revealed linkage with a maximum likelihood of the odds (LOD) score of 2.93 at Xp22.3. Linkage was excluded for Xp22.2 to Xqter.

CONCLUSIONS

Lisch corneal dystrophy is genetically different from Meesmann corneal dystrophy. Evidence was found for linkage of the gene for Lisch corneal dystrophy to Xp22.3.