What is mixed connective tissue disease (MCTD)?

Mixed connective tissue disease (MCTD) is a rare autoimmune disorder. An autoimmune disorder is one in which the immune system mistakenly views the body's own tissues as "invaders" and attacks them.

Mixed connective tissue disease has features of 3 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 3 disease listed above), develop another connective tissue disease over the course of several years. This is known as an "overlap syndrome."

How common is mixed connective tissue disease (MCTD)?

MCTD is a rare disease, occurring most often in women in their 20s and 30s. Children can also be diagnosed with the disease.

What causes mixed connective tissue disease (MCTD)?

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. Exposure to certain viruses or chemicals such as polyvinyl chloride and silica are other possible causes.

What are the symptoms of mixed connective tissue disease (MCTD)?

In the beginning stages, patients who have MCTD have symptoms similar to those of patients with other connective tissue disorders, including:

  • Fatigue.
  • Muscle pain with no apparent cause.
  • Joint pain.
  • Low-grade fever.
  • Raynaud phenomenon (reduced blood flow to the fingers, toes, ears, and nose, causing sensitivity, numbness, and loss of color in these areas).

Less common early symptoms may include:

  • Severe polymyositis, often in the shoulders and upper arms.
  • Acute (intense) arthritis.
  • Aseptic meningitis (inflammation of the brain and spinal cord meninges, not caused by a bacteria or virus).
  • Myelitis (inflammation of the spinal cord).
  • Gangrene (death and decay) of fingers or toes.
  • High fever.
  • Abdominal pain.
  • Neuropathy (nerve disorders) affecting the trigeminal nerve in the face.
  • Hearing loss.

The "classic" symptoms of MCTD are:

  • Raynaud phenomenon (see description above).
  • Swollen "sausage-like" fingers, sometimes temporary but at other times progressing into sclerodactyly (thin fingers with hardened skin and limited movement).
  • Inflamed joints and muscles.
  • Pulmonary hypertension (high blood pressure in the blood vessels of the lungs).