A 56-year-old woman has had weight loss accompanied by abdominal enlargement for the past 5 months. There is a family history of breast and ovarian carcinoma. On physical examination, there are no lesions of the cervix, and the uterus is normal in size, but there is a left adnexal mass. An abdominal ultrasound scan shows a 10-cm cystic mass in the left adnexal region, with scattered 1-cm peritoneal nodules, and ascites. Cytologic studies of peritoneal fluid show malignant cells. Which of the following mutated genes is most likely a factor in the development of this neoplasm?

Some familial cases of ovarian carcinoma (usually serous cystadenocarcinoma) are associated with the homozygous loss of the BRCA1 gene. This tumor-suppressor gene also plays a role in the development of familial breast cancers. Familial syndromes account for less than 5% of all ovarian cancers, however. The ERBB2 gene may be overexpressed in ovarian cancers; however, mutations of this gene do not give rise to familial tumors, and it is best known for an association with breast carcinomas. Mutations of the RAS and MYC oncogenes occur sporadically in many types of cancer. The RB1 gene, a tumor suppressor, can be involved in familial malignancies, including retinoblastoma and osteosarcoma.