Back in 1999, Easton stated in a paper on predisposition genes for breast cancer [29] that only 20–25% of the familial risk for breast cancer is due to susceptibility genes known at that time, including BRCA1, BRCA2, TP53, PTEN and ATM. More recent studies describe other high or moderately high risk and susceptibility genes of breast [30] and ovarian [31, 32] cancer. The gene discussed is PTEN; the disease is breast cancer.