Detection of point mutations at codon 12 of KI-ras in ophthalmic pterygia.
OBJECTIVE
Ophthalmic pterygium is a potentially vision-threatening lesion of unknown etiology, related to an exposure to solar light. Mutations to the ras genes are frequently observed in lesions related to an exposure to solar light. The present study aims at screening pterygia for mutations at codons 12 and 13 of the ras genes.


METHODS
In all, 50 pterygia were examined, together with respective blood samples and specimens of normal conjunctiva. A PCR reaction was performed to amplify sequences containing codons 12 and 13 of Ki-ras, H-ras, and N-ras. An RFLP analysis was then performed to detect point mutations at codon 12. The mutational status at codons 12 and 13 was further explored with sequencing of PCR products.


RESULTS
RFLP analysis revealed Ki-ras mutations at codon 12 in five (10%) of pterygia, whereas H-ras or N-ras mutations were not observed. Sequencing confirmed Ki-ras mutations at codon 12 and revealed absence of mutations at codon 13. The presence of Ki-ras mutations was significantly correlated with postoperative recurrence (P=0.02) and young age (P=0.04). Mutations were not observed in specimens of blood or normal conjunctiva for any of the genes examined.


CONCLUSIONS
The absence of N-ras mutations is in agreement with previous reports concerning mucosal lesions. The detection of Ki-ras mutations and the association with postoperative recurrence implies a possible role of Ki-ras in the clinical profile of pterygium. The mechanism of Ki-ras mutations is unclear and could be independent of the action of UV light.
Detorakis
E T
ET
Department of Clinical Virology, University of Crete, Greece.
Zafiropoulos
A
A
Arvanitis
D A
DA
Spandidos
D A
DA
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D018797:Cell Cycle Proteins / Q000235:genetics; D003062:Codon / Q000235:genetics; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004252:DNA Mutational Analysis; D005260:Female; D011905:Genes, ras / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D017354:Point Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D012150:Polymorphism, Restriction Fragment Length; D011625:Pterygium / Q000235:genetics* / Q000601:surgery; D012008:Recurrence
C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D003062:Codon; D050759:Cyclin-Dependent Kinase Inhibitor p21