WHAT IS MIXED CONNECTIVE TISSUE DISEASE (MCTD)?
Mixed connective tissue disease (MCTD) is an autoimmune disease first described in 1972 and is considered an "overlap" of three diseases, systemic lupus erythematosus (lupus), scleroderma and polymyositis. People with MCTD experience symptoms of each of these three diseases. In many cases, this mixed set of symptoms is eventually dominated by symptoms characteristic of one of the three illnesses, especially scleroderma or lupus.
HOW COMMON IS MCTD?
Mixed connective tissue disease is relatively rare, and the vast majority of people with the disease (80 percent) are women. MCTD occurs among people of all ages.
WHAT ARE THE WARNING SIGNS OF MCTD?
Most people with MCTD experience subtle signs of the disease many years before having it diagnosed. These symptoms can include swollen fingers, joint or muscle pain, acid reflux or difficulty swallowing, Raynaud's phenomenon (fingers become pale and numb in response to cold or emotional stress), muscle weakness, shortness of breath on activity, dry cough, a general malaise and fatigue. Symptoms of MCTD vary widely and each person's illness can be quite different.
Often a person with MCTD will visit many doctors before they receive a confirmed diagnosis. Although the diagnosis is often made based on the overlapping symptoms of lupus, scleroderma and polymyositis, a blood test for the ANA (anti-nuclear antibodies) – a general test of autoimmune disease – is taken. Abnormally high test results for ANA are an indicator for MCTD. Further testing of the blood will detect a more specific antibody, anti-ribonucleoprotein (RNP), which is present in almost all people who have MCTD.
Almost everyone with MCTD will have aching joints. The disease also inflames the muscle fibres causing weakness and soreness, especially in the muscles around the shoulders and hips.
Frequently, MCTD causes swollen hands and fingers. A purplish butterfly-shaped rash on the cheeks and the bridge of the nose, red patches on the knuckles, a violet discolouration of the eyelids and spidery veins on the face and hands may also occur.
WHAT CAUSES MCTD?
The cause of MCTD is not known. There may be a genetic predisposition and it is known that autoimmune diseases like MCTD run in extended families.
WHAT CAN YOU DO ABOUT MCTD?
Treatment of MCTD is directed at suppressing immune-related inflammation of tissues and is similar to treatment for lupus. Corticosteroids (for example, prednisone) are usually effective, especially when the disease is diagnosed early. Mild cases can be treated with nonsteroidal anti-inflammatory drugs (NSAIDs), hydroxychloroquine or similar drugs, and low doses of corticosteroids.
The more severe the disease, the higher the dose of corticosteroid needed. Prednisone is the most common corticosteroid used and is taken in pill form. Prednisone is usually considered when the symptoms of MCTD are not being controlled by other treatments.
Prednisone use needs to be carefully monitored because of its many side effects, and the drug must never be stopped abruptly. Some of the side effects from long-term use include cataracts, high blood pressure, sleep problems, muscle loss, bruising, thinning of the bones (osteoporosis), weight gain and increased risk of infections. The goal with this and most drugs is to find the lowest effective dose to avoid as many of the side effects as possible.
In severe cases of MCTD, immunosuppressive drugs (e.g. cytotoxic drugs) may also be needed. These drugs are powerful medications that suppress inflammation and the immune system. You may be prescribed these if your MCTD symptoms are difficult to control with prednisone alone or if you are experiencing side effects from prednisone.
In general, the more advanced the disease and the greater the organ damage, the less effective the treatment will be. Scleroderma-like damage to the skin and esophagus (pronounced e-sof-a-gus) is least likely to respond to treatment. Symptom-free periods can sometimes last for many years through minimal or no ongoing treatment. However, MCTD will progress in spite of treatment in about 13 percent of cases. In large part, the prognosis for MCTD is usually quite good.