What is Mixed Connective Tissue Disease (MCTD)

Mixed Connective Tissue Disease (MCTD) is a rare autoimmune disorder characterized by a combination of clinical features found in three other connective tissue diseases: systemic lupus erythematosus, systemic sclerosis, and polymyositis. Because Mixed Connective Tissue Disease involves the immune system attacking the body’s own healthy tissues, it can affect multiple organ systems simultaneously, requiring specialized, long-term management by a rheumatologist.

What body systems does Mixed Connective Tissue Disease affect?

Because Mixed Connective Tissue Disease is a systemic condition, it can impact almost every part of the body. The immune system, circulatory system, and respiratory system are frequently involved. Patients often experience inflammation in the skeletal and muscular systems, which can lead to joint pain and muscle weakness. Additionally, the integumentary (skin), digestive, and nervous systems may show signs of involvement, often manifesting as Raynaud’s phenomenon, where blood vessels in the fingers and toes constrict in response to cold or stress.

Who is typically affected by MCTD?

Mixed Connective Tissue Disease most commonly affects women, with a female-to-male ratio of approximately 9:1. While it can occur at any age, the onset of Mixed Connective Tissue Disease is most frequently observed in individuals between the ages of 15 and 35. There is no known geographic, racial, or ethnic predisposition.

How is Mixed Connective Tissue Disease identified?

The diagnosis of Mixed Connective Tissue Disease is complex because symptoms often overlap with other autoimmune conditions. A hallmark of the disease is the presence of high titers of a specific autoantibody known as anti-U1 RNP. Clinicians generally look for a combination of the following indicators to confirm the presence of Mixed Connective Tissue Disease:

• Raynaud’s phenomenon: A common early sign involving color changes in the fingers.


• Swollen fingers: Often referred to as "puffy fingers."


• Inflammatory arthritis: Pain and swelling in the joints.


• Myositis: Muscle inflammation and weakness.


• High levels of anti-U1 RNP antibodies: A diagnostic marker found in blood tests.

Next steps

• Consult with a board-certified rheumatologist to establish a personalized care plan, such as the methotrexate and prednisone regimens used by many of our 273 community members.


• Join the DiseaseMaps.org community to connect with others sharing their experiences with Mixed Connective Tissue Disease.


• Maintain a symptom diary to track how your body responds to treatments over time.

Medical disclaimer: This content is for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment; always seek the advice of your physician regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD): Mixed Connective Tissue Disease.


• Orphanet: Rare Disease Database (ORPHA:582).


• Online Mendelian Inheritance in Man (OMIM): Mixed Connective Tissue Disease entry.