What causes pediatric mixed connective-tissue disorder (MCTD)?

Updated: Oct 24, 2018
  • Author: Marisa S Klein-Gitelman, MD, MPH; Chief Editor: Lawrence K Jung, MD  more...
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Specific causes of mixed connective tissue disease remain undefined. [11]

  • Research suggests that many factors, including genetics, hormones, and environment, contribute to development of autoimmune syndromes.

  • As mentioned in the Introduction, the hallmark of mixed connective tissue disease is the presence of autoantibodies to U1 small nuclear ribonucleoproteins, in particular a 70-kDa U1 protein. During cell death or apoptosis, the 70-kDa protein is cleaved by caspase-3 into a small 40-kDa protein. Several research groups have described this apoptotic form.

  • Specific anti-RNP autoantibodies that preferentially bind to the apoptotic form of the U1 protein have been demonstrated in a group of patients with mixed connective tissue disease (29 of 53 tested). Furthermore, the concentration of the autoantibody is high early in the disease and decreases over time, suggesting that it correlates or represents an inciting event in disease onset.

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