Hot flashes arise when the thermoregulatory centers in the hypothalalmus are deprived of estrogen (see review by Rossmanith and Ruebberdt, 2009) and are a classical symptom of estrogen deprivation resulting from menopause and ovariectomy as well as the most common side effect of estrogen receptor antagonists and selective estrogen receptor modulators like tamoxifen (e.g., Bonneterre et al., 2000; Howell et al., 2005). This evidence concerns the gene ESR1 and menopause.