title: Disease subsets, antinuclear antibody profile, and clinical features in 127 French and 247 US adult patients with systemic sclerosis.
abstract: OBJECTIVE
  To investigate the specificities of antinuclear antibodies (ANA) associated with systemic sclerosis (SSc) disease classification and internal organ involvement among patients with SSc of different origins (European and American).
  
  
  METHODS
  Serum samples from 374 adult patients diagnosed with SSc were studied: 127 French patients (Paris) were compared with 247 US patients (Pittsburgh). Patients were classified into diffuse cutaneous (dc) and limited cutaneous (lc) SSc subsets. Antibodies associated with SSc were determined by protein and/or RNA immunoprecipitation, indirect immunofluorescence, and immunodiffusion.
  
  
  RESULTS
  SSc classification differed significantly in the 2 cohorts: lcSSc and overlap patients with lcSSc combined made up 76% of the French series versus 52% of the US group (p < 0.0001). The frequency of anti-RNA polymerase III antibody was significantly increased in US patients compared with French patients (p < 0.0001). The frequency of anti-topoisomerase I (topo I) antibody was significantly increased among French patients (p < 0.0048). Anti-topo I-positive French SSc patients were less likely to have dcSSc (38% vs 65%) and more likely to have milder disease than US anti-topo I-positive patients. The French dcSSc patients had lower proportions of joint/tendon manifestations and renal crisis (7% vs 17%), but more often had radiographic evidence of pulmonary fibrosis (57% vs 30%). French lcSSc patients had a lower frequency of pulmonary arterial hypertension than US lcSSc patients (9% vs 31%; p = 0.002).
  
  
  CONCLUSIONS
  There are disease classification and SSc-related serum autoantibody differences between French and American patients with SSc. These differences help to explain variations in clinical features reported from different geographic regions.
authors.affiliation: Rheumatology Unit, Bichat Hospital, Paris, France. olivier.meyer@bch.aphp.fr
authors.forename: Olivier C
authors.initials: OC
authors.lastname: Meyer
authors.forename: Noreen
authors.initials: N
authors.lastname: Fertig
authors.forename: Mary
authors.initials: M
authors.lastname: Lucas
authors.forename: Nathalie
authors.initials: N
authors.lastname: Somogyi
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Medsger
mesh_terms: D000328:Adult; D000974:Antibodies, Antinuclear / Q000097:blood*; D001323:Autoantibodies / Q000097:blood; D015331:Cohort Studies; D004264:DNA Topoisomerases, Type I / Q000276:immunology; D005260:Female; D005355:Fibrosis / Q000209:etiology / Q000473:pathology; D005602:France; D006801:Humans; D008297:Male; D008875:Middle Aged; D011658:Pulmonary Fibrosis / Q000209:etiology / Q000473:pathology; D012320:RNA Polymerase III / Q000276:immunology; D012595:Scleroderma, Systemic / Q000145:classification* / Q000150:complications / Q000276:immunology* / Q000473:pathology; D012871:Skin Diseases / Q000209:etiology / Q000473:pathology; D014481:United States
chemical_list: D000974:Antibodies, Antinuclear; D001323:Autoantibodies; D012320:RNA Polymerase III; D004264:DNA Topoisomerases, Type I