Alterations in tumor protein p53 (TP53), human epidermal growth factor 2, cyclin-dependent kinase inhibitr 2A (CDKN2A), Cyclin E1 (CCNE1), and F-box/WD repeat-containing protein 7 (FBXW7) genes are found in the majority of serous, high-grade endometrioid carcinomas and carcinosarcomas. The gene discussed is CDKN2A; the disease is endometrioid adenocarcinoma.