title: Association between PADI4 and rheumatoid arthritis: a meta-analysis.
abstract: OBJECTIVE
  Polymorphisms and haplotypes of the peptidylarginine deiminase type 4 gene (PADI4) have been reported to be associated with rheumatoid arthritis (RA) in a Japanese population. However, subsequent replication studies showed conflicting results. The aim of this study was to determine whether meta-analysis would prove the existence of the association.
  
  
  METHODS
  PubMed was searched using the term 'PADI4' for articles from the publication of the first study to December 2005. Replication studies that tested the association between PADI4 and RA were reviewed for meta-analysis. The Breslow-Day test for homogeneity across the studies was calculated. The Mantel-Haenszel procedure was used to pool odds ratios (OR) with 95% confidence intervals (CI) to evaluate the association.
  
  
  RESULTS
  Six replication studies, one from Japan and five from Europe and North America, fulfilled the selection criteria for inclusion in the meta-analysis. Homogeneity was confirmed across the replication studies. The common OR was 1.14 (95% CI = 1.07-1.21) for allelic distribution. The association was confirmed when only five replication studies in the European descent populations were combined (P = 0.0096, common OR = 1.10).
  
  
  CONCLUSIONS
  Our meta-analysis showed a positive association between PADI4 and RA not only in the Japanese population but also in populations of European descent.
authors.affiliation: Institute of Rheumatology, Tokyo Women's Medical University, 10-22 Kawada, Shinjuku, Tokyo 162-0054, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Iwamoto
authors.forename: K
authors.initials: K
authors.lastname: Ikari
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Kuwahara
authors.forename: Y
authors.initials: Y
authors.lastname: Toyama
authors.forename: T
authors.initials: T
authors.lastname: Tomatsu
authors.forename: S
authors.initials: S
authors.lastname: Momohara
authors.forename: N
authors.initials: N
authors.lastname: Kamatani
mesh_terms: D001172:Arthritis, Rheumatoid / Q000235:genetics*; D016022:Case-Control Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D006867:Hydrolases / Q000235:genetics*; D011110:Polymorphism, Genetic; D000080002:Protein-Arginine Deiminase Type 4; D000076342:Protein-Arginine Deiminases
chemical_list: D006867:Hydrolases; C000629235:PADI4 protein, human; D000080002:Protein-Arginine Deiminase Type 4; D000076342:Protein-Arginine Deiminases