Such changes include upper airway narrowing and edema that are related to decreased oncotic pressure, the presence of estrogen receptors in the upper airway, and reduced functional residual capacity and chest wall compliance.1 In addition, the obesity epidemic in many countries in the developed world, including the United States, affects women of childbearing age,2 and is likely a major contributor to the presence of obstructive sleep apnea (OSA) in this young population. The gene discussed is ESR1; the disease is obstructive sleep apnea syndrome.