In order to select and develop an assay suitable to detect the AKT1 E17K mutation in DNA from FFPE samples of ER+ breast tumors or tumors of gynecological origin (ovarian, endometrial and cervical) in a clinical trial, an assay with 100% specificity (i.e. no false positive test results) and good sensitivity (i.e. limited number of false-negative test results) was required. This evidence concerns the gene AKT1 and breast neoplasm.