A few diagnostic markers for specific tumors are available: Prostate specific antigen (PSA) for prostate cancer, Cancer antigen 125 (CA125) for ovarian cancer, calcitonin for medullary thyroid cancer, alpha fetoprotein (AFP) for liver cancer, and human chorionic gonadotropin (HCG) for germ cell tumors. The gene discussed is KLK3; the disease is ovarian cancer.