CHEK2 and ovarian cancer: The remaining 88 percent of breast and ovarian cancers can be attributed to the involvement of other genes such as tumor protein (TP53) [MIM 191170], phosphatase and tension homolog (PTEN) [MIM 601728], checkpoint kinase 2 (CHEK2) [MIM 604373], and estrogen Receptor 1 (ESR) [MIM 133430].