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February 8, 2012

Mixed Connective Tissue Disease
(MCTD)

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Medical Editor:
MCTD vs. UCTD (Mixed Connective Tissue Disease vs. Undifferentiated Connective Tissue Disease)

Medical Author: William C. Shiel Jr., MD, FACP, FACR
Medical Editor: Melissa Conrad Stöppler, MD

Learn the difference between MCTD and UCTD.I note that some viewers have been requesting some clarification of the meaning of the terms "mixed connective tissue disease" (MCTD) and "undifferentiated connective tissue disease" (UCTD).

Connective tissue diseases are a special group of rheumatic diseases (diseases that feature abnormalities of the muscles and/or joints) that can be associated with arthritis. The cause(s) for the connective tissue diseases is (are) unknown. They are characterized as a group by the presence of spontaneous overactivity of the body's immune (defense) system. This overactivity results in the production of unusual antibodies that are found in the blood. The antibodies themselves may or may not cause any problems in patients with connective tissues diseases, but they are commonly found in the blood as a characteristic feature.

The connective tissues are the structural portions of our body that essentially hold the cells of the body together. These tissues form a framework, or matrix, for the body. The connective tissues are composed of two major structural protein molecules, collagen and elastin. There are many different types of collagen protein that vary in amount in each of the body's tissues. Elastin has the capability of stretching and returning to its original length, like a spring or rubber band. Elastin is the major component of ligaments (tissues that attach bone to bone) and skin. In patients with connective tissue diseases, it is common for collagen and elastin to become injured by inflammation. Diseases in which inflammation of collagen tends to occur are also referred to as collagen diseases.

What are connective tissues?

The connective tissues are the structural portions of our body that essentially hold the cells of the body together. These tissues form a framework or matrix for the body. The connective tissues are composed of two major structural molecules, collagen and elastin. There are many different collagen proteins that vary in amount in each tissue of the body. Elastin is another protein that has the capability of stretching and returning to original length like a spring. Elastin is the major component of ligaments (tissues which attach bone to bone).

Connective tissue diseases are disorders featuring abnormalities involving the collagen and elastin. Connective tissue diseases are often characterized by a variety of immune abnormalities that are common for each particular type of illness.

What diseases characteristically affect connective tissue?

Diseases of connective tissue that are strictly inheritable (due to genetic inheritance) include Marfan syndrome (can have tissue abnormalities in the heart, aorta, lungs, eyes, and skeleton) and Ehlers-Danlos syndrome (may have loose, fragile skin or loose [hyperextensible] joints). Pseudoxanthoma elasticum is an inherited disorder of elastin.

Other diseases of connective tissue do not have specific gene abnormalities as their sole cause. These connective tissue diseases occur for unknown reasons. They are characterized as a group by the presence of spontaneous over activity of the immune system, which results in the production of unusual antibodies into the blood.

The classic immune-related connective tissue diseases include systemic lupus erythematosus, rheumatoid arthritis, scleroderma, polymyositis, and dermatomyositis. Each of these diseases has a characteristic presentation with typical clinical findings that doctors can recognize during an examination. Each also has characteristic blood test abnormalities and abnormal antibody patterns. However, each of these diseases can evolve slowly or rapidly from very subtle abnormalities before demonstrating the classic features that help in the diagnosis. When these conditions have not developed the classic features of a particular disease, doctors will often refer to the condition as "undifferentiated connective tissue disease." This implies that the characteristic features that are used to define the classic connective tissue disease are not present, but some symptoms or signs of connective disease exist. Individuals with undifferentiated connective tissue disease may never develop a fully definable condition or they may eventually develop a classic connective tissue disease.




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  • Related Diseases & Conditions

    • Rheumatoid Arthritis
      • Rheumatoid arthritis is an autoimmune disease that causes chronic inflammation of the joints, the tissue around the joints, as well as other organs in the body. Because it can affect multiple other organs of the body, rheumatoid arthritis is referred to as a systemic illness and is sometimes called rheumatoid disease.
    • Scleroderma
      • Scleroderma is an autoimmune disease of the connective tissue. It is characterized by the formation of scar tissue (fibrosis) in the skin and organs of the body, leading to thickness and firmness of involved areas. Scleroderma is also referred to as systemic sclerosis, and the cause is unknown. Treatment of scleroderma is directed toward the individual features that are most troubling to the patient.
    • Polymyositis
      • Polymyositis is a disease of the muscle featuring inflammation of the muscle fibers. It results in weakness of the muscles which can be severe and when associated with skin rash, is referred to as dermatomyositis. Although the cause of this disease is unknown, diagnosis includes physical examination of muscle strength, blood tests for muscle enzymes, electrical tests of muscle and nerves, and conformation by a muscle biopsy. Treatment of Polymyositis and Dermatomyositis includes high doses of cortisone-related medications, immune suppression, and physical therapy.
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Mixed Connective Tissue Disease

What is polymyositis?

Polymyositis is a disease of muscle featuring inflammation of the muscle fibers. The cause of the disease is not known. It begins when white blood cells, the immune cells of inflammation, spontaneously invade muscles. The muscles affected are typically those closest to the trunk or torso. This results in weakness that can be severe. Polymyositis is a chronic illness with periods of increased symptoms, called flares or relapses, and minimal or no symptoms, known as remissions.

Polymyositis is slightly more common in females. It affects all age groups, although its onset is most common in middle childhood and in the 20s. Polymyositis occurs throughout the world. Polymyositis can be associated with skin rash and is then referred to as "dermatomyositis." It also can affect other areas of the body and is, therefore, referred to as a systemic illness. Occasionally, it is associated with cancer or with other diseases of connective tiss...

Read the Polymyositis article »







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