title: TNF microsatellites polymorphism is associated with rheumatoid arthritis. Confirming evidence in northwestern Colombians.
abstract: OBJECTIVE
  To examine the contribution of tumor necrosis factor alpha (TNF) microsatellite (a to e) polymorphism to the genetic risk of developing rheumatoid arthritis (RA) in a northwestern Colombian population.
  
  
  METHODS
  This was an association study in which 108 RA patients and 222 matched individuals were enrolled. HLA-DRB1 and DQB1 polymorphisms were evaluated to examine for linkage disequilibrium between these loci and TNF micro- satellites. Genotyping was performed using denaturing polyacrylamide gels and polymerase chain reaction-sequence techniques.
  
  
  RESULTS
  By unconditional logistic regression analysis, the TNFa6 allele (OR=2.37, 95%CI 1.07-5.24) and the TNFb4 allele (OR=3.01, 95%CI 1.07-9.00) were observed to be associated with disease. These associations were independent of HLA-DR and HLA-DQ since linkage disequilibrium between HLA class II and TNF microsatellites was not observed. In addition, patients with the TNFa8 allele had a five times greater risk of developing extra-articular manifestations as compared to patients without this allele (OR=5.07, 95%CI 1.14-22.52), regardless of age and the duration of disease. Haplotype analysis disclosed a protective effect for TNFa7/b7/c1/d4/e3/-308G/-238G.
  
  
  CONCLUSIONS
  These results confirm that the TNF locus exerts a primary influence on both susceptibility to and the severity of RA.
authors.affiliation: Cellular Biology and Immunogenetics Unit, Corporación para Investigaciones Biológicas (CIB), Medellín, Colombia.
authors.forename: L M
authors.initials: LM
authors.lastname: Gomez
authors.forename: E A
authors.initials: EA
authors.lastname: Ruiz-Narváez
authors.forename: R
authors.initials: R
authors.lastname: Pineda-Tamayo
authors.forename: A
authors.initials: A
authors.lastname: Rojas-Villarraga
authors.forename: J-M
authors.initials: JM
authors.lastname: Anaya
mesh_terms: D000328:Adult; D001172:Arthritis, Rheumatoid / Q000208:ethnology / Q000235:genetics*; D003105:Colombia; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics*; D008875:Middle Aged; D011110:Polymorphism, Genetic; D012044:Regression Analysis; D012307:Risk Factors; D012720:Severity of Illness Index; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
chemical_list: D014409:Tumor Necrosis Factor-alpha