Mixed connective tissue disease (MCTD) is a rare autoimmune disorder featuring signs and symptoms of three different disorders: lupus, scleroderma and polymyositis. An autoimmune disorder is one in which the body's immune system turns against the body it was designed to protect for unknown reasons.

Symptoms of the different diseases that make up MCTD usually don't begin at the same time. Early symptoms may include fatigue, mild fever, cold and numb fingers, swelling that gives fingers a sausage-like appearance and muscle and joint pain. In the later stages of the disease, the heart, lungs, kidney or other organs may be affected.

Sometimes called degenerative joint disease or degenerative arthritis, osteoarthritis (OA) is the most common chronic condition of the joints. In normal joints, a firm, rubbery material called cartilage covers the end of each bone. Cartilage provides a smooth, gliding surface for joint motion and acts as a cushion between the bones. In OA, the cartilage breaks down, causing pain, swelling and problems moving the joint.

Psoriatic arthritis is an autoimmune disease, meaning it occurs when the body's immune system mistakenly attacks healthy tissue, in this case the joints and skin. The faulty immune response causes inflammation that triggers joint pain, stiffness and swelling. The inflammation can affect the entire body and may lead to permanent joint and tissue damage if it is not treated early and aggressively. Most people with psoriatic arthritis have skin symptoms before joint symptoms. However, sometimes the joint pain and stiffness strikes first. In some cases, people get psoriatic arthritis without any skin changes. The disease may lay dormant in the body until triggered by some outside influence, such as a common throat infection.

Reactive arthritis is an inflammatory type of arthritis which affects the joints, and may affect the eyes, skin and urinary tract (bladder, vagina, urethra). It occurs when bacteria enters the blood stream from one or both of the following areas of the body

• Urogenital tract. Bacteria can enter through the vagina or urethra during sexual contact and spread to the bladder.
• Gastrointestinal (GI) tract. Bacteria can enter the body if you eat spoiled food or food that came into contact with contaminated surfaces.

Rheumatoid arthritis (RA) is an autoimmune disease in which the body's immune system - which normally protects its health by attacking foreign substances like bacteria and viruses - mistakenly attacks the joints. This creates inflammation that causes the tissue that lines the inside of joints (the synovium) to thicken, resulting in swelling and pain in and around the joints. The synovium makes a fluid that lubricates joints and helps them move smoothly. Rheumatoid arthritis most commonly affects the joints of the hands, feet, wrists, elbows, knees and ankles. The joint effect is usually symmetrical. That means if one knee or hand if affected, usually the other one is, too. Because RA also can affect body systems, such as the cardiovascular or respiratory systems, it is called a systemic disease. Systemic means "entire body."