Apart from alterations in a few well-known drivers, including KRAS and HER2 amplification, in ovarian serous and mucinous carcinomas and mutations in ARID1A, PIK3CA, and PTEN genes as well as mismatch repair (MMR) deficiency in ovarian endometrioid carcinomas, comparatively little is known about molecular alterations in these tumors (12). The gene discussed is PTEN; the disease is ovarian endometrioid carcinoma.