Abstract
Germline mutations of the phosphatase and tensin homolog (PTEN) gene (UCSC ID, uc001kfb.2; RefSeq, NM_000314), encoding deleted on chromosome 10,1 cause 80% of autosomal-dominant Cowden syndrome and occur in 1 in 200 000 live births. These mutations are characterized by macrocephaly and typical mucocutaneous features (trichilemmomas, papillomatous papules) and hamartomas, with increased risk of various malignancies, approximately 10% lifetime risk for thyroid cancer, and as much as 50% lifetime risk for female breast cancer over the general population.1-8