title: Overlapping syndromes, undifferentiated connective tissue disease, and other fibrosing conditions.
abstract: Many patients presenting with symptoms suggestive of a connective tissue disease do not fulfill criteria for a specific connective tissue disease at initial presentation. Some of these patients with undifferentiated connective tissue disease eventually develop a specific connective tissue disease. Recently, a large cohort of 213 patients from different centers with undifferentiated connective tissue disease of early onset were enrolled in a prospective protocoled study. Baseline characteristics, including antinuclear antibody profiles, were reported. The aim of this study was to define predictors for the development of specific organ-system involvement and connective tissue diseases in early undifferentiated connective tissue disease. Many patients show overlapping features of two or more connective tissue diseases. The presence of autoantibodies to U1-ribonucleoproteins has been associated with a particular overlap syndrome, mixed connective tissue disease. Most anti-U1-ribonucleoprotein-positive patients with undifferentiated connective tissue disease at presentation appear to develop mixed connective tissue disease over the course of disease. Although levels of anti-U1-ribonucleoprotein do not seem to be related to disease activity, this association suggests a pathogenetic relationship between anti-U1-ribonucleoprotein and mixed connective tissue disease. Genetic studies have shown that patients with antibodies against the 70-kD component of U1-ribonucleoprotein share a common epitope within the groove of their DR molecules at antigen-binding region, pointing to a particular antigen involved in the induction of these antibodies that may be relevant in the etiopathogenesis of associated disease.
authors.affiliation: Department of Clinical Immunology, University Hospital, Groningen, The Netherlands.
authors.forename: C G
authors.initials: CG
authors.lastname: Kallenberg
mesh_terms: D000974:Antibodies, Antinuclear / Q000097:blood; D003240:Connective Tissue Diseases / Q000209:etiology* / Q000276:immunology; D005260:Female; D005355:Fibrosis; D006801:Humans; D008297:Male; D008947:Mixed Connective Tissue Disease / Q000209:etiology / Q000235:genetics / Q000276:immunology; D017412:Ribonucleoprotein, U1 Small Nuclear / Q000276:immunology; D013577:Syndrome
chemical_list: D000974:Antibodies, Antinuclear; D017412:Ribonucleoprotein, U1 Small Nuclear