title: Autoimmune diseases and autoantibodies in the first degree relatives of patients with systemic sclerosis.
abstract: OBJECTIVE
  To determine aggregation of autoimmune diseases in the first degree relatives (FDR) of patients with systemic sclerosis (SSc) and to investigate frequencies of antinuclear antibodies (ANA) and other autoantibodies in the FDRs and spouses of patients with SSc.
  
  
  METHODS
  Information on FDRs including history of autoimmune disease was obtained from unrelated SSc probands in the Scleroderma Family Registry and DNA Repository. FDRs were contacted to verify any reported autoimmune diseases. The prevalence of autoimmune disease in probands' families was compared with the corresponding prevalence in controls' families as reported in the literature. Furthermore, sera from probands' FDRs and spouses in addition to unrelated controls were investigated for the presence of autoantibodies (ANA).
  
  
  RESULTS
  We investigated 4612 FDRs of 1071 SSc probands. SSc probands with anti-centromere antibodies (ACA) and limited disease type were more likely to report familial autoimmunity (p=0.022 and p=0.041, respectively). The four most prevalent autoimmune diseases among SSc probands' FDRs were hypothyroidism (4%), Rheumatoid arthritis (1.5%), hyperthyroidism (1.3%) and systemic lupus erythematosus-SLE (0.4%). Compared to control families, SLE, hypothyroidism and hyperthyroidism were more common in SSc probands' families. The most striking increase for familial prevalence was observed in SLE (OR=16.98, 95% CI=1.02-227.82, p=0.004). ANA was present in 14.2% of probands' FDR's and 8.6% of spouses and did not differ from the prevalence of ANA among controls (p=0.124 and p=0.477, respectively). Only two FDRs of probands had ACA while none had anti-topoisomerase antibodies.
  
  
  CONCLUSIONS
  Our study implies varying degrees of risk for familial autoimmunity among subtypes of SSc and provides further support for common genetic and potentially environmental factors leading to SSc and SLE.
authors.affiliation: Division of Rheumatology and Immunogenetics, University of Texas Health Science Center at Houston, Houston, TX, USA.
authors.forename: Rajpreet K
authors.initials: RK
authors.lastname: Arora-Singh
authors.forename: Shervin
authors.initials: S
authors.lastname: Assassi
authors.forename: Deborah J
authors.initials: DJ
authors.lastname: del Junco
authors.forename: Frank C
authors.initials: FC
authors.lastname: Arnett
authors.forename: Marilyn
authors.initials: M
authors.lastname: Perry
authors.forename: Uzma
authors.initials: U
authors.lastname: Irfan
authors.forename: Roozbeh
authors.initials: R
authors.lastname: Sharif
authors.forename: Tony
authors.initials: T
authors.lastname: Mattar
authors.forename: Maureen D
authors.initials: MD
authors.lastname: Mayes
mesh_terms: D000368:Aged; D000974:Antibodies, Antinuclear / Q000097:blood; D001327:Autoimmune Diseases / Q000097:blood / Q000453:epidemiology* / Q000276:immunology; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D015995:Prevalence; D012307:Risk Factors; D012595:Scleroderma, Systemic / Q000453:epidemiology* / Q000276:immunology
chemical_list: D000974:Antibodies, Antinuclear