PTEN and PTEN hamartoma tumor syndrome: PTEN (phosphatase and tensin homolog deleted on chromosome ten), a tumor suppressor located at 10q23, is commonly epigenetically downregulated or somatically mutated in many types of cancer; further, germline mutations in PTEN are associated with PTEN hamartoma tumor syndrome (PHTS), and predisposing for some forms of cancer10–15.