title: Association between VDR polymorphisms and rheumatoid arthritis disease: Systematic review and updated meta-analysis of case-control studies.
abstract: BACKGROUND
  Vitamin D receptor (VDR) polymorphisms have been inconsistently investigated in rheumatoid arthritis (RA). However, published studies demonstrated differences concerning design and effect size. A meta-analysis is necessary to determine the magnitude of the association between VDR polymorphisms and RA risk.
  
  
  OBJECTIVE
  The aim of the current study was to quantify the magnitude of the association between TaqI, BsmI, and FokI VDR polymorphisms with RA risk.
  
  
  METHODS
  Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a systematic search and meta-analysis of the literature were conducted. Analyses were performed in the random effects model by using recessive, dominant, codominant, homozygous, and allele contrast models.
  
  
  RESULTS
  A total of 1703 cases and 2635 controls in 12 case-control studies were included in the meta-analyses. Results indicated a significant association between TaqI polymorphism and RA disease in homozygous, codominant and allele contrast models (P=0.008, P=0.015, P=0.006 and P=0.002, respectively). Association between BsmI polymorphism and RA risk was marginal in the dominant, codominant and allele contrast models (P=0.057, P=0.071, and P=0.069, respectively). Te association between FokI polymorphism and RA risk was significant in the recessive, dominant and allele contrast models (P=0.045, P=0.027, and P=0.013, respectively). Subgroup analysis showed that publication year, ethnicity, age, latitude, and estimated 25(OH)D levels influenced significantly the association between VDR polymorphisms and RA risk.
  
  
  CONCLUSIONS
  TaqI and FokI VDR polymorphisms contributed significantly to RA risk. Study characteristics influenced the association between VDR polymorphisms and RA disease.
authors.affiliation: Tunis El Manar University, Faculty of Medicine Tunis, Division of Histology and Immunology, Department of Basic Sciences, 15 Rue Djebel Lakdar, 1007 Tunis, Tunisia. Electronic address: kalttizaoui@gmail.com.
authors.forename: Kalthoum
authors.initials: K
authors.lastname: Tizaoui
authors.affiliation: Tunis El Manar University, Faculty of Medicine Tunis, Division of Histology and Immunology, Department of Basic Sciences, 15 Rue Djebel Lakdar, 1007 Tunis, Tunisia.
authors.forename: Kamel
authors.initials: K
authors.lastname: Hamzaoui
mesh_terms: D000483:Alleles; D001172:Arthritis, Rheumatoid / Q000235:genetics*; D016022:Case-Control Studies; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D016017:Odds Ratio; D011110:Polymorphism, Genetic; D018167:Receptors, Calcitriol / Q000235:genetics*
chemical_list: D018167:Receptors, Calcitriol
keywords: BsmI; FokI; Meta-analysis; Rheumatoid arthritis; TaqI; VDR polymorphism