4 out of 5 autoimmune disorders strike women

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Why do more women than men get autoimmune diseases?
There are more than 80 autoimmune diseases that can be life-altering, even life-threatening. These occur when the immune system goes awry and mistakenly attacks healthy parts of the body rather than infectious invaders such as bacteria and viruses. It's often described as the body's inability to distinguish "self" from "non-self."
Autoimmune diseases afflict 23.5 million Americans, according to the Department of Health and Human Services, although the American Autoimmune Related Diseases Association estimates the number at more than twice that.
Women account for nearly 80 percent of all cases — for reasons not well understood. Most often, they hit women in their reproductive years, often complicating pregnancy.
The immune system produces a type of B cell that secretes autoantibodies. These substances can bind to the body's cells and tissues. In people with healthy immune systems, several mechanisms keep these B cells in check and purge them from the body. However, the process can malfunction. When this happens, these B cells proliferate, producing autoantibodies that go on the attack — and an autoimmune disease results.
Autoantibodies can damage joints, the digestive system, the heart, lungs, kidneys and other organs, the nerves, hair follicles and the connective tissue in the skin and blood vessels. Although each disorder is distinct, they frequently share such symptoms as fatigue, dizziness and low-grade fever. Inflammation is a hallmark of all of them.
Among the more common autoimmune diseases are rheumatoid arthritis, which attacks the lining of the joints; Type 1 diabetes, which destroys cells needed to make blood-sugar-controlling insulin; multiple sclerosis, which damages linings around the nerves, affecting the brain and spinal cord; Crohn's disease and irritable bowel syndrome, which harm the gastrointestinal tract; scleroderma, which causes abnormal growth of connective tissue in the skin and blood vessels; psoriasis, in which new skin cells rise up too fast, resulting in thick red patches and scales; Hashimoto's disease, which attacks the thyroid gland; and systemic lupus erythematosus, often just called lupus, which can hurt the joints, skin, heart, lungs and kidneys.
"If you tell your friends and teachers that you have cancer, they understand it, but if you tell them you have lupus, they don't understand that it took you three hours to get out of bed because your joints were so sore and inflamed," says Judith James, chair of the Oklahoma Medical Research Foundation. "Lupus can also affect your brain and cause depression, and affect your ability to think. It's a terrible disease.''
Researchers believe that gene mutations, the environment and even the human microbiome are involved in autoimmune diseases. They often run in families.
"Autoimmune diseases appear to be a mismatch between genes and the environment," says David Hafler, chairman of the department of neurology at the Yale School of Medicine. "It's not one gene; there are hundreds of common genetic variants which together lead to disease. But all this also raises the question of why we have not found the smoking gun that defines the gender risk."
Women typically mount a more vigorous immune response than men to infections and vaccinations, producing higher levels of antibodies. In the case of autoimmune disorders, this trait seems to backfire.
"Robust immunity in females can be good evolutionarily, but too much immunity can be bad if directed toward self," says Rhonda Voskuhl, a professor of neurology at UCLA.
Scientists believe that sex hormones also may play a role, because many autoimmune disorders occur in women soon after puberty. Sex chromosomes, specifically the X chromosome, may have an influence.
Interestingly, men who develop these diseases often experience worse symptoms than women, probably because they lack "whatever factors protect men or make it easier for women to get these diseases," Hafler says.