title: Lack of association between interleukin-18 polymorphisms and rheumatoid arthritis.
abstract: OBJECTIVE
  To assess the association of the polymorphisms of the interleukin-18 (IL-18) gene with rheumatoid arthritis (RA) and with risk factors for cardiovascular diseases (CVD).
  
  
  METHODS
  This sample comprised 97 patients with RA and 151 healthy controls. In the patients, risk factors for CVD were analyzed, such as cholesterol levels, arterial hypertension, smoking habit, C-reactive protein (CRP) level, and rheumatoid factor. DNA was extracted and the single nucleotide polymorphisms (SNP) at the -607C/A and -137G/C positions of the IL-18 gene were assessed in both groups. The Hardy-Weinberg equilibrium (HWE) was calculated and the odds ratio (OR) test performed, considering a 95% CI and P < 0.05.
  
  
  RESULTS
  The frequencies of the -607A allele in patients with RA and in controls were 0,443 and 0.424, respectively, and of the -137C allele, 0.304 and 0.291, respectively. The genotype frequencies were in HWE, except for controls in the -137 locus (P = 0.006). Association of the polymorphisms of the IL-18 gene was found with neither RA nor risk factors for CVD, including cholesterol level and CRP (P > 0.05). In addition, more smokers were found among patients with RA as compared with controls (OR = 1.691; P = 0.088), and the CRP levels were slightly higher in patients who smoked than in patients who did not (OR = 2.673; P = 0.061).
  
  
  CONCLUSIONS
  In this sample of patients with RA in the South of Brazil, association of the polymorphisms of the IL-18 gene was observed with neither RA nor risk factors for CVD.
authors.affiliation: Laboratory of genetic polymorphisms, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
authors.forename: Ticiana Della Justina
authors.initials: TD
authors.lastname: Farias
authors.forename: Luisa Matos do
authors.initials: LM
authors.lastname: Canto
authors.forename: Mayara Delagnelo
authors.initials: MD
authors.lastname: Medeiros
authors.forename: Aline Fernanda Rodrigues
authors.initials: AF
authors.lastname: Sereia
authors.forename: Lia Kubelka Fernandes de Carlos
authors.initials: LK
authors.lastname: Back
authors.forename: Filipe Martins de
authors.initials: FM
authors.lastname: Mello
authors.forename: Adriana Fontes
authors.initials: AF
authors.lastname: Zimmermann
authors.forename: Ivânio Alves
authors.initials: IA
authors.lastname: Pereira
authors.forename: Yara Costa Netto
authors.initials: YC
authors.lastname: Muniz
authors.forename: Andrea Rita
authors.initials: AR
authors.lastname: Marrero
authors.forename: Ilíada Rainha de
authors.initials: IR
authors.lastname: Souza
mesh_terms: D001172:Arthritis, Rheumatoid / Q000150:complications / Q000235:genetics*; D002318:Cardiovascular Diseases / Q000150:complications / Q000235:genetics; D005260:Female; D006801:Humans; D020382:Interleukin-18 / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic; D012307:Risk Factors
chemical_list: D020382:Interleukin-18