Rheumatoid arthritis is an autoimmune disease. Normally, your immune system helps protect your body from infection and disease. In rheumatoid arthritis, your immune system attacks healthy tissue in your joints. It can also cause medical problems with your heart, lungs, nerves, eyes and skin.
Doctors don't know what starts this process, although a genetic component appears likely. While your genes don't actually cause rheumatoid arthritis, they can make you more likely to react to environmental factors — such as infection with certain viruses and bacteria — that may trigger the disease.
Your sex: Women are more likely than men to develop rheumatoid arthritis.
Age: Rheumatoid arthritis can occur at any age, but it most commonly begins in middle age.
Family history: If a member of your family has rheumatoid arthritis, you may have an increased risk of the disease.
Smoking: Cigarette smoking increases your risk of developing rheumatoid arthritis, particularly if you have a genetic predisposition for developing the disease. Smoking also appears to be associated with greater disease severity.
Excess weight: People who are overweight appear to be at a somewhat higher risk of developing rheumatoid arthritis.
Courtesy: Mayo Clinic
Part 01: Rheumatoid arthritis (part 1)