Two novel mutations ofPTEN gene in Japanese patients with Cowden syndrome

A novel mutation of the PTEN gene in a Japanese patient with Cowden syndrome and bilateral breast cancer

Cowden syndrome (CS), also known as multiple hamartoma syndrome, is an autosomal dominant cancer syndrome associated with a high risk of breast and thyroid cancers. The phosphatase and tensin homolog gene (PTEN) encodes a lipid phosphatase that contains a PTPase domain and a C2 domain and plays a role as a tumor suppressor that negatively regulates the cell-survival signaling pathway initiated by phosphatidylinositol 3-kinase (PI3K). PTEN inhibits angiogenesis, and germline mutations of the PTEN gene are associated with CS. We screened for mutations in the PTEN gene in two unrelated Japanese patients with CS. In one patient, who suffered from bilateral breast cancer, thyroid adenoma, and gastric malignant lymphoma, we found a single-base substitution in exon 2 (115G>C) of the PTEN gene. This transversion results in a germline missense mutation (A39P). To date, nine different mutations have been identified in exon 2 of the PTEN gene in patients with CS and variant CS; however, the A39P missense mutation has not been reported previously. We also detected a previously reported nonsense mutation, 697C>T, resulting in R233X.

Cancer phenomics: RET and PTEN as illustrative models

Cancer phenomics, the systematic acquisition and objective documentation of host and/or somatic cancer phenotypic data at many levels, is a young field compared with other molecular-based 'omics'. Two relatively advanced phenomic paradigms are associated with phosphatase and tensin homologue (PTEN) and rearranged during transfection (RET), genes that are associated with cancer predisposition syndromes in addition to developmental disorders. The phenomic characterization of PTEN and RET underscores the importance of incorporating robust phenomics into the host 'omic' profile, and shows that the evolution of phenomics will be crucial to the advancement of personalized medicine.

Germline PTEN mutations are rare and highly penetrant

Cowden syndrome (multiple hamartoma syndrome, MIM 158350) is an early onset syndrome characterized by multiple hamartomas in the skin, mucous membranes, breast, thyroid and endometrium. Patients with Cowden syndrome have increased risk of breast cancer, thyroid cancer and endometrial cancer. In 1997 germline mutations in PTEN were demonstrated to cause Cowden syndrome. We report the results of diagnostic and predictive testing in all families with Cowden syndrome or suspected Cowden syndrome registered at the Norwegian cancer family clinics. PTEN mutations were found in all six families meeting the clinical criteria for Cowden syndrome, in none of the two families assumed to have Cowden syndrome but not fulfilling the criteria, and in none of the eight families selected in our computerized medical files to have a combination of breast and thyroid cancers. Age-related penetrances for the various neoplasms are given. All families but one were small and de novo mutations were found.