Analysis of PTEN gene mutations in Korean patients with Cowden syndrome and polyposis syndrome.

OBJECTIVE

PTEN (phosphatase and tensin homologue deleted in chromosome 10) is a candidate tumor suppressor gene. Mutations of this gene are responsible for PTEN hamartoma tumor syndromes, including Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome, Proteus syndrome, and Proteus -like syndromes. Recently, PTEN mutations were identified in several human neoplasms. We analyzed the DNA of various organs and lesions in Korean patients with Cowden syndrome, their family members, and patients with familial adenomatous polyposis for germline or somatic PTEN mutations.

METHODS

The 11 patients included in this study were 5 patients with Cowden syndrome, 4 of their family members, and 2 patients with familial adenomatous polyposis. Deletions and mutations in exons 1 to 9 of the PTEN gene were evaluated by polymerase chain reaction-single strand conformation polymorphism and sequencing analysis in esophageal acanthosis, gastric polyps, colonic polyps, skin lesions, and peripheral blood mononuclear cells. To exclude common polymorphisms, 240 controls were tested.

RESULTS

All patients with Cowden syndrome showed several to numerous polyps in the gastrointestinal tract. A missense mutation at codon 217 (GTC to GAC, Val to Asp) in exon 7 was identified in one Cowden syndrome patient, and a nonsense mutation at codon 211 (TGC to TGA, Cys to stop) in exon 6 was identified in a second patient. Identical mutations were found in all tissue samples, including colonic polyps, from each patient. No PTEN mutations were found in their family members or in any patient with familial adenomatous polyposis. None of tested controls contained a mutation.

CONCLUSIONS

We have identified two new germline PTEN mutations in Korean patients with Cowden syndrome. Mutations in the introns and regulatory regions of the PTEN gene may be present in additional patients with Cowden syndrome and polyposis syndrome.