PTEN and Cowden disease: PTEN is a multi-functional tumour suppressor gene that regulates the AKT/PKB signalling pathway and is commonly mutated in many cancers including endometrial cancer.32 Loss-of-function germline mutations in PTEN are responsible for Cowden syndrome, which exerts a lifetime risk of endometrial cancer of up to 28%.9 Lacey and colleagues studied SNPs in the PTEN gene region; however, none showed significant differences in frequency between 447 endometrial cancer cases and 439 controls of European ancestry.33