In 50% of high-grade serous cancers, homologous recombination DNA repair is dysfunctional, as are the notch and FOXM1 signaling pathways. They also almost always have p53 mutations. Other than this, mutations in high-grade serous carcinoma are hard to characterize beyond their high degree of genomic instability. "BRCA1" and "BRCA2" are essential for homologous recombination DNA repair, and germline mutations in these genes are found in about 15% of people with ovarian cancer. The most common mutations in BRCA1 and BRCA2 are the frameshift mutations that originated in a small founding population of Ashkenazi Jews.