Endocrine therapies such as tamoxifen and aromatase inhibitors have been shown to increase bone loss or fracture risk in both pre- and postmenopausal women with early-stage breast cancer (Powles et al., 1996; Sverrisdóttir et al., 2004; Aihara et al., 2010; Zaman et al., 2012; Tseng et al., 2018). The gene discussed is CYP19A1; the disease is breast cancer.