Abstract
Purpose::
To determine if mutations in the coding region of the keratin 12 (KRT 12) or keratin 3 (KRT 3) gene are responsible for two cases of Meesmann’s corneal dystrophy (MCD).
Methods::
Slit lamp examinations were performed on patients for disease diagnosis. DNA samples were collected from the affected probands (Proband A and B) and their unaffected family members after obtaining their consent, and PCR-based sequence analyses were performed to screen for mutations in the KRT3 and KRT12 genes. Selected exons of KRT3 and KRT12 were amplified by polymerase chain reaction (PCR) and are directly sequenced.
Results::
Slit-lamp examination revealed that the two probands had MCD. Gene mutation analysis identified a heterozygous mutation Met129Thr in the exon 1 of KRT12 in proband A but not in her unaffected family member. This mutation located at the helix initiation motif of KRT12, which may disrupt the formation of keratin3/12 fiber. DNA sequence analysis failed to find mutations in KRT12 for proband B. However, a novel heterozygous mutation Glu547Asp was discovered in the exon 9 of KRT3 in Proband B. This mutation is located at the highly conserved Glycine-loop motif of KRT3. Therefore, it may affect protein-protein interactions between keratin 3 and other proteins including keratin 12.
Conclusions::
We identified a known Met129Thr mutation in the KRT 12 gene in proband A with MCD and discovered a novel mutation Glu547Asp in the KRT3 gene that is associated with MCD in proband B.
Keywords: cornea: basic science • gene screening