What is mixed connective-tissue disorder (MCTD)?

Updated: Nov 25, 2020
  • Author: Eric L Greidinger, MD; Chief Editor: Herbert S Diamond, MD  more...
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Answer

Mixed connective-tissue disease (MCTD) was first recognized by Sharp and colleagues (1972) in a group of patients with overlapping clinical features of systemic lupus erythematosus (SLE), scleroderma, and myositis, with the presence of a distinctive antibody against what now is known to be U1-ribonucleoprotein (RNP). [1, 2]

MCTD has since been more completely characterized and is now recognized to consist of the following core clinical and laboratory features [3, 4] :

Four different classification and diagnostic criteria for MCTD have been developed. [6] For example, the Alarcón-Segovia diagnostic criteria consist of a positive anti–U1 RNP titer (>1:1600) and at least three of the following five clinical findings [7, 8, 9] :

  • Hand edema
  • Synovitis
  • Biologically or histologically proven myositis
  • Raynaud phenomenon
  • Acrosclerosis with or without proximal systemic sclerosis

Nevertheless, whether MCTD is a distinct disease entity has been in question since shortly after its original description. A minority of authors continue to suggest that MCTD represents subgroups or early stages of disorders such as SLE or systemic sclerosis, or an overlap syndrome. [10] Ciang and colleagues propose that MCTD would more accurately be termed undifferentiated autoimmune rheumatic disease. [11]  

The overall goal of therapy for MCTD is to control symptoms and to maintain function. Target medical therapy to specific organ involvement and extent of disease activity, and monitor for the development of complications (eg, pulmonary hypertension, infection).


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