By Bayla Rothschild, Staff Writer
Many people suffer from autoimmune diseases, but recent studies show that women are much more likely than men to be diagnosed with one. One study found that 67% of autoimmune diagnoses are in women and that 18 out of the 20 most common autoimmune diseases are more prevalent in women. So, why does this occur?
It is important to understand what an autoimmune disease is on the biological level. The immune system protects humans and animals from harmful bacteria and viruses by sending out white blood cells to eliminate them before they make that human or animal sick. Autoimmune disorders occur when someone’s immune system is more active than it should be, so it ends up attacking and damaging healthy tissue. Autoimmune disorders can take place in all parts of the body; it all depends on where the immune system is malfunctioning. Rheumatoid arthritis, colitis and Crohn’s disease are all examples of autoimmune diseases.
This difference between men and women comes from the fact that women have two X chromosomes while men only have one. One cannot live without an X chromosome as it contains many protein-specifying genes that are required for life. Since women have two X chromosomes, in theory they should produce double the amount of the proteins coded on the X chromosome, but that would be lethal. Therefore, early on in embryogenesis (the process by which a fertilized egg grows into an embryo), one of the X chromosomes gets shut down and proteins are not produced from that chromosome throughout life.
The molecule responsible for inactivating the second X chromosome is called Xist (X-inactive specific transcript). Xist is made up of RNA, which binds to specific genes on the X chromosome and reduces the likelihood that they are read and interpreted. This prevents the excess of protein that would be produced should both X chromosomes produce it. Xist is found in all the cells of a woman’s body, but it does not appear in male cells at all.
However, this process generates a combination of proteins to bind together in a way that creates a strong immune response. Autoimmunity begins with the appearance of autoantibodies, which are antibodies that target healthy parts of the body. After a careful analysis of many types of autoantibodies, many were found to be connected with many of the protein complexes associated with Xist. Some of these autoantibodies were markers of one autoimmune disorder, while others were connected to several. Because all the cells in a woman’s body produce Xist, and many of the common autoimmunity markers are associated with Xist, it makes sense that women are more likely than men to have autoimmune diseases.
In a broader context, the research in the area of autoimmune diseases displays the importance of health related research not only focusing on males. Traditionally, many studies relating to healthcare have mainly focused on the health of males which ends up neglecting the biological differences between men and women. These differences between the sexes are present even on the most microscopic of levels, and this means that even seemingly non-sex-specific health issues are impacted by sex. Ultimately, acknowledging these genetic nuances is a necessity in order to accurately understand, diagnose and treat many health conditions including autoimmune diseases.
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