Ankylosing spondylitis (AS) is an autoimmune disease that does not appear the same in women as it does it men. It is easier to diagnose in men because they usually show the joint and skeletal changes more clearly on imaging while women may have more peripheral damage. I think there is a certain number of women who think they have cfs that actually have AS. The symptoms vary a lot from person to person. If you are a woman who has experienced back pain off and on since your teens or twenties, read up on the symptoms and make sure you could not have it. The pains can show up at times in the tendons that connect with bone or pain abdomen, feet, neck knees etc. These pains vary and come and go. It also has the cfs symptoms of fatigue, cognitive issues, irritable bowel (perhaps 40% of patients), etc. The problem is that the disease progresses if it is not found early enough and the medical profession has not done a good job of identifying women with it. It is interesting that there is a connection between adhd and AS.