They frequently exhibit molecular abnormalities in several genes, such as somatic mutations of CTNNB1 (Catenin (Cadherin-Associated Protein), Beta 1), PTEN (phosphatase and tensin homolog) and PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit α) in endometrioid carcinomas; KRAS (Kirsten rat sarcoma viral oncogene homolog) mutations in mucinous carcinomas; PIK3CA activating and ARID1A inactivating mutations in clear cell carcinomas, and others. The gene discussed is PIK3CA; the disease is mucinous adenocarcinoma.