Progression and Possible Complications of Mixed Connective Tissue Disease (MCTD)

What is mixed connective tissue disease (MCTD)?

Mixed connective tissue disease (MCTD) is a rare autoimmune condition; it is often referred to as an overlap disease because the symptoms of MCTD overlap with other connective tissue conditions, including polymyositis, scleroderma and systemic lupus erythematosus (SLE). In some cases, MCTD also mimics symptoms of rheumatoid arthritis.

Autoimmune diseases develop when the immune system mistakenly attacks healthy cells; mixed connective tissue disease occurs when the immune system attacks the fibers that support the framework of the body. An estimated 25% of individuals with a connective tissue disease develop another connective tissue condition over the course of several years.

Prognosis

Symptoms of mixed connective tissue disease are highly individualized. Some people may be symptom-free for many years. However, even with treatment, an estimated 13% of individuals with an MCTD diagnosis experience progressive, severe symptoms that can lead to fatal complications within six to 12 years. The heart, lungs, kidneys and other organs may be affected in the later stages of the condition. Pulmonary hypertension is the leading cause of death associated with MCTD. Fortunately, the 10-year survival rate of MCTD is approximately 80%.

Possible complications

Infections are a common complication of mixed connective tissue disease. Serious complications of MCTD include the following:

• Pulmonary hypertension is high blood pressure in the arteries to the lungs that may result in death.
• Interstitial lung disease affects the ability to breathe due to lung scarring.
• Heart disease may occur when the heart becomes enlarged or inflamed. Individuals with lupus often have fluid accumulation around the heart that can cause seizures.
• Kidney damage or failure is a common complication that occurs in one-fourth of those with MCTD.
• Damage to the digestive tract may occur, resulting in abdominal pain.
• Anemia occurs in up to 75% of individuals with MCTD.
• Hearing loss has been reported in approximately 50% of individuals with MCTD.
• Necrosis (tissue death or gangrene) may occur in those with severe Raynaud’s disease.
• Aortic aneurysm (greater risk in individuals who also have Marfan syndrome, an inherited disorder that affects connective tissue.)
• Osteogenesis imperfecta (a genetic disorder causing bones to break easily) may develop, causing breathing difficulty due to spine and rib cage issues.