 Hi, I am Dr. Vijay Rao. I am a consultant working in the rheumatology department in Manipal Hospital's Bangalore. Mostly rheumatoid arthritis is genetically mediated, so a gene defect causes this. Most of my patients ask, does that mean it's hereditary because none of my family members had it? And the answer is no. Genetically mediated means the gene is altered in the patient's body causing something called as mutation and hence the function of the gene is altered. This altered functional gene produces certain chemicals in the body called antibodies which destroys the joint. So this is an autoimmune disease where body's own immune system attacks the joints and other parts of the body destroying it and hence it's called self-directed immunity or autoimmunity. One I've already listed which is genetically prone people. And how do we know that? Although I said that it's genetic, it's not hereditary but if you have family members having rheumatoid arthritis then you are definitely at slightly more risk. If one does smoking then smoking causes a chemical in the body, chemical process in the body called citrullination. This happens in the lungs which produces antibodies called anti-CCP antibodies which are basically like ballistic missiles attacking the joints and internal organs. So smoking, genetic abnormalities, strong family history and sedentary lifestyle is certainly associated with rheumatoid arthritis. As well as all these factors another important thing is obesity. So being lean and physically active certainly gives you lesser chance of developing rheumatoid arthritis.