CCNE1 and ovarian serous carcinoma: Amplification of the cyclin E1 gene (CCNE1, 19q12) is the key genetic event driving CCNE1 overexpression, occurring in approximately 20% of high grade serous ovarian carcinomas (HGSOC) [5, 6], 10–15% of uterine serous and carcinosarcoma cases [7, 8], and 15% of clear cell carcinomas (CCOC) [9].