Novel germline mutation of the PTEN gene in a Japanese family with Cowden disease.

We report a novel germline mutation of the PTEN gene in a Japanese family with Cowden disease. A 46-year-old Japanese man and his mother were diagnosed as having Cowden disease. Their physical examinations revealed multiple facial trichilemmoma, oral mucosal papillomatosis, palmoplantar keratosis, and gastrointestinal polyposis. The single-strand conformation polymorphism (SSCP) analysis showed an abnormal band on exon 7 of their PTEN gene. Direct sequence analysis of exon 7 detected a TAAA insertion to codon 221, producing a stop codon (c.663ins TAAA).