Women are far more likely to suffer from autoimmune disorders such as rheumatoid arthritis, multiple sclerosis and scleroderma, and scientists wanted to know why.
Recently, researchers at Stanford University tried to determine why women comprise about 80% of these cases. According to a new study published Feb. 1 in Cell, the answer might be in our genetics.
The researchers note that biological men have just one X chromosome while women have two. In place of two x chromosomes, men have a Y chromosome, which researchers say only contains a handful of active genes.
X chromosomes provide much more activity, but women's bodies have to compensate for that by inactivating one of the X chromosomes. This inactivation is because of a molecule called Xist.
The study says when a female cell dies due to tissue injury, Xist will invariably be exposed to the immune system. The study suggests that Xist contributes to several steps in the progression of autoimmune disease.
The researchers noted that other factors can also lead to autoimmune diseases, which is why men do sometimes develop them.
“Every cell in a woman’s body produces Xist,” said Howard Chang, professor of dermatology and of genetics at Stanford. “But for several decades, we’ve used a male cell line as the standard of reference. That male cell line produced no Xist and no Xist/protein/DNA complexes, nor have other cells used since for the test. So, all of a female patient’s anti-Xist-complex antibodies — a huge source of women’s autoimmune susceptibility — go unseen.”
The researchers say the study will hopefully lead to a better way to predict autoimmune disorders before they develop.
According to the American Autoimmune Related Diseases Association, nearly 50 million Americans have one or more autoimmune disorders. The group says these disorders are among the 10 leading causes of death among women in the U.S.
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