Pediatric Mixed Connective Tissue Disease (MCTD) is a rare disease in children that has symptoms of arthritis along with features of scleroderma, dermatomyositis and lupus. It is characterized by lab tests showing the presence of specific antibodies to nuclear proteins (specifically, RNP).

Pediatric MCTD occurs in children under the age of 16. MCTD is three times more frequent in girls than boys.

MCTD is a type of autoimmune disease. The immune system primarily works to protect the body from infections. However, in autoimmune diseases, immune cells attack the body’s own tissues, resulting in inflammation and tissue damage.

The cause of MCTD is unknown. One theory is that development of MCTD requires the combination of two factors: infection and genetics. In this theory, the body has an abnormal response to a viral infection. The immune system attacks and clears the virus, but it does not stop the attacking process. Instead, it begins to attack the body’s own tissue(s). There is evidence that some people are more likely to have this type of abnormal immune response. Also, the tendency for the immune system to react this way is partially inherited. However, MCTD does not occur from inheriting a single gene mutation, since it is very rare for other family members to develop MCTD. In some people, there appear to be several genes or groups of genes which either allow the immune system to cause the illness or fail to protect the person from developing it.

MCTD is not contagious.

MCTD often begins with fever, decreased energy, and weakness. The symptoms can range from mild to life-threatening.

Pediatric MCTD can go into periods of remission where symptoms are not present. The two most characteristic findings in MCTD at the time of diagnosis are arthritis and Raynaud’s phenomenon. Arthritis is painful, swollen joints with tenderness, loss of motion, and heat or redness. Raynaud’s phenomenon is a sudden, reversible, sequence of skin color changes (pale, blue and/or red) commonly affecting fingers and toes, which may happen after cold exposure. Raynaud’s may also occur in other inflammatory connective tissue diseases such as scleroderma.

Pulmonary hypertension is an uncommon but very dangerous complication of pediatric MCTD, typically developing slowly and silently. Its symptoms, like shortness of breath and chest pain, must be reported to your doctor immediately.

There is no known cure for pediatric MCTD. However, there is effective treatment which can reduce or eliminate symptoms, allowing children with MCTD to lead healthy, productive lives. Treatment is tailored to a child’s pattern of symptoms. Over time, some patients develop mild arthritis and only need symptom relief. Patients that develop lung disease will require steroids and other immune-suppressing medications. Raynaud’s phenomenon responds well to protection from the cold, such as wearing mittens. Some children with Raynaud’s may need drugs, like calcium channel blockers.

Pediatric MCTD is a treatable disease. The long-term outcome depends on a child’s disease characteristics and response to medications. Therefore, the outcome is variable and unpredictable. Some children achieve remission and may discontinue their medications. However, other children may have active disease for many years; some may have more severe symptoms than others. Despite the challenges children with MCTD and their families face, the majority of children grow up to lead an active, productive life.