Mixed Connective Tissue Disease (MCTD)

What is it?

Mixed connective tissue disease has features of three other connective tissue diseases:

  • Systemic lupus erythematosus (SLE) – An inflammatory disease that can affect many different organs. Symptoms include fever, fatigue, joint pains, weakness, and skin rashes on the face, neck, and upper body.
  • Scleroderma – Abnormal thickening and hardening of the skin, underlying tissue, and organs
  • Polymyositis – Muscle inflammation (swelling)

About 25% of patients with a connective tissue disease (such as dermatomyositis, rheumatoid arthritis, Sjogren’s syndrome, and the three disease listed above), develop another connective tissue disease over the course of several years. This is known as an “overlap syndrome.”


Complications of MCTD

Mixed connective tissue disease can lead to serious complications, including:

  • High blood pressure in the lungs (pulmonary hypertension). This condition is the main cause of death in people with mixed connective tissue disease.
  • Interstitial lung disease. This large group of disorders can cause scarring in your lungs, which affects your ability to breathe.
  • Heart disease. Parts of the heart may become enlarged, or inflammation may occur around the heart. Heart disease is the cause of death in about 20 percent of people with mixed connective tissue disease.
  • Kidney damage. About one-fourth of people with mixed connective tissue disease develop kidney problems. Sometimes, that damage can lead to kidney failure.
  • Digestive tract damage. You may develop abdominal pain and problems with digesting food.
  • About 75 percent of people with mixed connective tissue disease have iron deficiency anemia.
  • Tissue death (necrosis). People with severe Raynaud’s phenomenon can develop gangrene in the fingers.

Hearing loss. Often unrecognized, hearing loss may occur in as many as half the people with mixed connective tissue disease.


What causes it?

The causes of MCTD are not known. It is not directly inherited, although some research shows that the disease may occur more often in people with a family history of connective tissue disease.


How is MCTD diagnosed?

A diagnosis can be difficult to make because the three conditions (SLE, scleroderma, and polymyositis) that can be seen in MCTD usually occur one after the other over a long period of time, rather than at the same time. It may take several years to make an accurate diagnosis of MCTD.

There are four features that point to MCTD rather than another connective tissue disorder:

  • High concentrations in blood tests of a particular antibody called anti-U1-RNP (ribonucleoprotein)
  • An absence of the severe kidney and central nervous system problems often found in SLE patients
  • Severe arthritis and pulmonary hypertension, which may not be found in either SLE or scleroderma patients
  • Raynaud phenomenon, and swollen hands or puffy fingers, which occur in only about 25% of SLE patients


How is MCTD treated?

Treatment for MCTD must be tailored to each particular patient, depending on the organs that are affected and how severe the condition is. Some patients may need treatment only during flare-ups, while others may require constant care.

Treatment considerations include the following:

  • Pulmonary hypertension is the most common cause of death in people with MCTD, and must be treated with antihypertensive medications.
  • People with a mild form of MCTD may not need treatment, or only low doses of nonsteroidal anti-inflammatory drugs (such as ibuprofen and naproxen), antimalarials, or low-dose corticosteroids (such as prednisone) to treat inflammation.
  • Higher doses of corticosteroids are often used to manage the signs and symptoms of moderate to severe MCTD. If major organs are affected, the patient may have to take immunosuppressants (to suppress the immune system).
  • MCTD patients are also at risk of developing heart disease, including an enlarged heart or pericarditis (inflammation around the heart). Patients may need regularly scheduled electrocardiograms to monitor the heart’s condition.
  • Long-term use of steroids can lead to side effects such as bone loss due to osteoporosis, tissue death due to lack of blood flow, muscle weakness, and infections. Patients must see their doctor on a regular basis to monitor and control these possible effects.
  • Women with MCTD who are thinking of becoming pregnant should first talk to their doctor. Pregnancy can increase flare-ups of the disease, and babies born to women with MCTD may suffer from low birth weight.
  • Patients who have a long-term, incurable condition such as MCTD should develop ways of dealing with their disease. This includes seeking advice from medical and mental health professionals; proper diet and exercise (if not overly fatigued); learning as much as possible about the disease; and joining a chronic illness support group.