PTEN and Cowden disease: The number of genes are associated with multiple cancer syndromes for example phosphatase and tensin homolog protein (PTEN) (Cowden syndrome), TP53 (Li-Fraumeni), STK11/LKB1 (Peutz-Jeghers), ataxia telangiectasia (ATM) (Louis-Bar Syndrome), and NBS1 (Nijmegen breakage syndrome), but other genes associated with hereditary breast cancer are emerging.