Familial peripheral keratopathy without PAX6 mutation

To describe the clinical features of a familial abnormality of the corneal stem cells and to investigate the role of PAX6 mutations in the affected family members.

A family with multiple generations of peripheral keratopathy was evaluated. Because of the corneal phenotypic similarity to aniridia-related keratopathy, it was hypothesized that the affected patients might have a dominantly inherited mutation of PAX6 on chromosome 11. Commercial sequencing of germline DNA from 1 affected family member did not identify any PAX6 mutations in the exons or intron-exon boundary regions. Because the commercial analysis is not designed to identify PAX6 deletions, germline DNA was collected from 5 unaffected and 2 additional affected family members. DNA repeat markers in the region of PAX6 were analyzed to determine whether this chromosomal region segregates with the disease phenotype.

Affected family members with this autosomal dominant peripheral corneal abnormality showed evidence of progressive corneal stem cell dysfunction. Several individuals demonstrated corectopia, and 1 individual had ectropion uvea but no other iris or ocular abnormalities associated with aniridia. Genotyping data of affected and unaffected family members demonstrated that the PAX6 region does not segregate with the disease phenotype.

The features of this autosomal dominant abnormality show some similarity to aniridia, although the classic characteristics of severe iris hypoplasia and macular hypoplasia are absent. Mutational screening and genotyping could not conclusively clarify a role for PAX6 in this disease phenotype, suggesting that it is a distinct clinical and genetic disease entity, not a variant of aniridia.