Women are more susceptible to autoimmune diseases due to the malfunction of the two X chromosomes in their body system. A study from Stanford University shows that women also have a molecule called Xist (pronounced "exist") which actually plays a role in maintaining the excess X chromosome in the female body. The main task of the Xist molecule is to deactivate the second X chromosome, which can trigger a poor immune response. Sex hormones are also considered the main cause of this difference. This is because most autoimmune diseases are diagnosed after puberty.

In addition, women do produce more antibodies compared to men. The reason is that a woman's body needs to adapt to protect the life of the future baby she will carry. That is why there are more antibodies in women's bodies compared to men's. "Currently, there is clear evidence that gender bias in autoimmune disease patients is not only related to hormones, but also to the presence of X chromosomes and the process of inactivation," said Claire Rougeulle, an epigenetics expert from France.

Although this deactivation process occurs, 15 to 23 percent of genes remain active. Genes that should no longer function continue to do so. This is what causes lupus or autoimmune-related diseases. Meanwhile, the Xist molecule is responsible for deactivating the second X chromosome. Many proteins in the body work together with this molecule in autoimmune disorders attacked by harmful antibodies called autoantibodies. Autoantibodies are considered harmful because they attack the body's own cells rather than attacking foreign invaders like bacteria or viruses.

To understand this relationship, Rougeulle and Celine Morey, two epigenetic experts in France, conducted research on female mice. They wanted to know what would happen if the X chromosome in female mice was not completely inactivated. This study was designed to prevent the X chromosome in female mice from being completely inactivated. As a result, the mice showed symptoms similar to lupus disease.