Human epididymis protein 4 (HE4), normally expressed in the epididymis, endometrial glands and respiratory tract [6,7], is up-regulated in both early and late stage ovarian cancer [6-9] including 90% of serous carcinoma, and adenocarcinomas of the lung and endometrium [10,11]. The gene discussed is WFDC2; the disease is ovarian cancer.