Rheumatoid arthritis (RA) is a chronic inflammatory disorder  affecting many joints, including those in the hands and feet. People suffering from this condition may experience complications in other parts of the body, such as the skin, eyes, lungs, heart, and blood vessels.
An autoimmune disorder, rheumatoid arthritis occurs when your immune system mistakenly attacks your own body’s tissues. In severe cases, it attacks internal organs. Rheumatoid arthritis affects the lining of your joints, causing a painful swelling that can eventually result in bone erosion and joint deformity.
The inflammation associated with rheumatoid arthritis is what can damage other parts of the body as well. Early rheumatoid arthritis tends to affect your smaller joints first, especially those in the fingers and feet.
As the disease progresses, symptoms  often spread to the wrists, knees, ankles, elbows, hips, and shoulders. In most cases, symptoms occur in the same joints on both sides of your body.
About 40 percent of the people who have rheumatoid arthritis also experience signs and symptoms that don’t involve the joints. Rheumatoid arthritis can affect many structures  that are not joint, including skin, eyes, lungs, heart, kidneys, salivary glands, nerve tissue, bone marrow, and blood vessels.
Rheumatoid arthritis signs and symptoms may vary in severity and may even come and go. Periods of increased disease activity, called flares, alternate with periods of relative remission. When the swelling and pain fade or disappear. Over time, RA can cause joints to deform and shift out of place.
The following are the causes  of RA: