Background-Petuz-Jeghers syndrome (PJS) is a rare, autosomal dominant,
polyposis syndrome, associated with an increased risk of gastrointest
inal and extragastronintesinal malignancy. Occasionally dysplasia occu
rs in PJS polyps. Aims-In colorectal carcinomas, mutations in codon 12
of the K-ras oncogene are common and are found at similar frequency i
n precursor adenomas. Therefore, K-ras codon 12 point mutations in PJS
polyps were evaluated. Materials and methods-Fifty two PJS polyps, in
cluding four with dysplasia, collected from 19 patients with PJS, were
analysed for mutations in the K-ras codon 12 by a mutant enriched pol
ymerase chain reaction procedure, followed by allele specific oligodeo
xynucleotide hybridisation. Results-A K-ras codon 12 mutation was iden
tified in one colonic polyp with dysplasia. The mutation was found in
the non-neoplastic epithelial cells and not in the dysplastic componen
t of the polyp. Conclusions-K-ras codon 12 point mutations are very ra
re in PJS polyps, by contrast with colorectal adenomas. The findings s
upport precious evidence that there seems to be no intrinsic relation
between K-ras codon 12 mutation and dysplasia.