LncRNA Xist, which is dependent on the production of BRCA1 and may participate in regulating breast cancer development, is highly expressed in BRCA1-like breast cancer as a predictive biomarker (Sirchia et al., 2005, 2009; Vincent-Salomon et al., 2007; Schouten et al., 2016). The gene discussed is BRCA1; the disease is breast cancer.