title: Specific association of type 1 diabetes mellitus with anti-cyclic citrullinated peptide-positive rheumatoid arthritis.
abstract: OBJECTIVE
  The co-occurrence of autoimmune diseases such as rheumatoid arthritis (RA) and type 1 diabetes mellitus (DM) has been reported in individuals and families. In this study, the strength and nature of this association were investigated at the population level in a Swedish case-control cohort.
  
  
  METHODS
  For this case-control study, 1,419 patients with incident RA diagnosed between 1996 and 2003 were recruited from university, public, and private rheumatology units throughout Sweden; 1,674 matched control subjects were recruited from the Swedish national population registry. Sera from the subjects were tested for the presence of antibodies to cyclic citrullinated peptide (anti-CCP), rheumatoid factor (RF), and the 620W PTPN22 allele. Information on a history of diabetes was obtained by questionnaire, telephone interview, and/or medical record review. The prevalence of type 1 DM and type 2 DM was compared between patients with incident RA and control subjects and further stratified for the presence of anti-CCP, RF, and the PTPN22 risk allele.
  
  
  RESULTS
  Type 1 DM was associated with an increased risk of RA (odds ratio [OR] 4.9, 95% confidence interval [95% CI] 1.8-13.1), and this association was specific for anti-CCP-positive RA (OR 7.3, 95% CI 2.7-20.0), but not anti-CCP-negative RA. Further adjustment for the presence of PTPN22 attenuated the risk of anti-CCP-positive RA in patients with type 1 DM to an OR of 5.3 (95% CI 1.5-18.7). No association between RA and type 2 DM was observed.
  
  
  CONCLUSIONS
  The association between type 1 DM and RA is specific for a particular RA subset, anti-CCP-positive RA. The risk of developing RA later in life in patients with type 1 DM may be attributed, in part, to the presence of the 620W PTPN22 allele, suggesting that this risk factor may represent a common pathway for the pathogenesis of these 2 diseases.
authors.affiliation: Division of Rheumatology, Immunology, and Allergy, Brigham and Women's Hospital, Boston, MA 02114, USA. kliao@partners.org
authors.forename: Katherine P
authors.initials: KP
authors.lastname: Liao
authors.forename: Marie
authors.initials: M
authors.lastname: Gunnarsson
authors.forename: Henrik
authors.initials: H
authors.lastname: Källberg
authors.forename: Bo
authors.initials: B
authors.lastname: Ding
authors.forename: Robert M
authors.initials: RM
authors.lastname: Plenge
authors.forename: Leonid
authors.initials: L
authors.lastname: Padyukov
authors.forename: Elizabeth W
authors.initials: EW
authors.lastname: Karlson
authors.forename: Lars
authors.initials: L
authors.lastname: Klareskog
authors.forename: Johan
authors.initials: J
authors.lastname: Askling
authors.forename: Lars
authors.initials: L
authors.lastname: Alfredsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D000906:Antibodies / Q000097:blood / Q000276:immunology*; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000235:genetics / Q000276:immunology*; D001327:Autoimmune Diseases / Q000097:blood / Q000235:genetics / Q000276:immunology; D016022:Case-Control Studies; D003922:Diabetes Mellitus, Type 1 / Q000235:genetics / Q000276:immunology*; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000235:genetics / Q000276:immunology; D005260:Female; D020022:Genetic Predisposition to Disease; D006306:Health Surveys; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008875:Middle Aged; D010456:Peptides, Cyclic / Q000276:immunology*; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22 / Q000235:genetics; D012217:Rheumatoid Factor / Q000097:blood / Q000276:immunology; D013548:Sweden; D055815:Young Adult
chemical_list: D000906:Antibodies; D010456:Peptides, Cyclic; C487763:cyclic citrullinated peptide; D012217:Rheumatoid Factor; C516765:PTPN22 protein, human; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22