In 2002, a 46-year-old woman with a history of Raynaud’s syndrome and hypothyroidism was diagnosed with HR-positive [estrogen receptor (ER) 95%, progesterone receptor (PR) 95%] HER2-negative low-grade invasive cancer (NOS) of the right breast cancer (pT1cpN1aM0). The gene discussed is ESR1; the disease is hypothyroidism.