Mixed Connective Tissue Disease

What is mixed connective tissue disease (MCTD)?

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

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 your face, neck and upper body.
• Scleroderma: Abnormal thickening and hardening of your skin, underlying tissue and organs.
• Polymyositis: Muscle inflammation (swelling).

About 25% of people with a connective tissue disease (such as dermatomyositis, rheumatoid arthritis, Sjogren’s syndrome, and the three diseases 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 and people assigned female at birth in their 20s and 30s. Children can also be diagnosed with the disease.

What causes mixed connective tissue disease (MCTD)?

The causes of MCTD aren’t known. It’s not directly inherited, although some research shows that the disease may occur more often in people with a biological 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, people who have MCTD have symptoms similar to those with other connective tissue disorders, including:

• Fatigue.
• Muscle pain with no apparent cause.
• Joint pain.
• Low-grade fever.
• Raynaud phenomenon (reduced blood flow to 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 your shoulders and upper arms.
• Acute (intense) arthritis.
• Aseptic meningitis (inflammation of your brain and spinal cord meninges, not caused by a bacteria or virus).
• Myelitis (inflammation of your spinal cord).
• Gangrene (death and decay) of fingers or toes.
• High fever.
• Abdominal pain.
• Neuropathy (nerve disorders) affecting the trigeminal nerve in your 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 your lungs).

How is mixed connective tissue disease diagnosed (MCTD)?

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 severe kidney and central nervous system problems often found in SLE patients.
• Severe arthritis and pulmonary hypertension, which may not be found in people with either SLE or scleroderma.
• Raynaud phenomenon, and swollen hands or puffy fingers, which occur in only about 25% of people with SLE.

How is mixed connective tissue disease treated (MCTD)?

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

Treatment considerations include:

• 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, you may have to take immunosuppressants (to suppress your immune system).
• People who have MCTD are also at risk of developing heart disease, including an enlarged heart or pericarditis (inflammation around their heart). You may need regularly scheduled electrocardiograms to monitor your heart’s condition.

What can be expected following treatment for mixed connective tissue disease (MCTD)?

• 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. You must see your doctor on a regular basis to monitor and control these possible effects.
• Women and people assigned female at birth 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.
• People 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.

Can mixed connective tissue disease be prevented (MCTD)?

As the causes of MCTD aren’t known, there isn’t a way of preventing the disease.

What is the long-term outlook for people with mixed connective tissue disease (MCTD)?

As MCTD is composed of a number of connective tissue disorders, there are many different possible outcomes, depending on the organs affected, the degree of inflammation and how quickly the disease progresses. With proper treatment, 80% of people survive at least 10 years after diagnosis.