Ars Technica: “Eighty percent of patients with autoimmune diseases are female. These diseases are one of the top 10 leading causes of death for women under 65, and cases are increasing annually worldwide. There is evidence suggesting that it’s females’ double complement of X chromosomes that puts them at such heightened risk for autoimmune diseases. Female cells have two X chromosomes, whereas males have one X chromosome and one Y chromosome (at least in mammals).”