The disorder is common, nowadays. 75 percent of the cases are of women. What actually happens in this disease? It is our immune system that defends our body against diseases and it helps the body to identify foreign cells. But, in autoimmune disease, our immune system attacks our healthy cells by considering them to be foreign by mistake. How many types of tissues get affected due to this, it all depends on the type of this disorder. Yes, the disorder has more than 80 different types. It leads to abnormal cell growth and organ function.