title: A new haplotype of PDCD1 is associated with rheumatoid arthritis in Hong Kong Chinese.
abstract: OBJECTIVE
  The programmed death 1 (PD-1) molecule is a negative regulator of T cells, and a genetic association between PD-1 and systemic lupus erythematosus and rheumatoid arthritis (RA) in Caucasians has been reported. The aim of this study was to investigate the association of PDCD1 polymorphisms and haplotypes with RA in the Chinese population.
  
  
  METHODS
  Three single-nucleotide polymorphisms (SNPs), PD-1.1 G/A, PD-1.3 G/A, and PD-1.5 C/T, were genotyped in 180 patients with RA and 647 healthy controls in a case-control association study. Analyses of the association of genotypes and alleles with disease, haplotype construction, and linkage disequilibrium (LD) were performed.
  
  
  RESULTS
  We constructed haplotypes with the alleles of markers PD-1.1 G/A and PD-1.5 C/T and found that the GT haplotype was overrepresented in patients with RA (31%) compared with controls (23%) (P = 0.001, odds ratio [OR] 1.54, 95% confidence interval [95% CI] 1.18-1.99). Among GT double homozygotes the risk of RA was increased even further (OR 2.31, 95% CI 1.31-4.08, P = 0.006). We also observed that the AA genotype of SNP PD-1.1 was associated with a decreased risk for developing RA (OR 0.38, 95% CI 0.15-0.99, P = 0.034). No association for SNP PD-1.5 in RA was found, and SNP PD-1.3 was nonpolymorphic in the Chinese population.
  
  
  CONCLUSIONS
  Our results support the involvement of PDCD1 as a susceptibility gene for RA in the Chinese population.
authors.affiliation: The University of Hong Kong, Hong Kong SAR, China.
authors.forename: Eric Kai-Pang
authors.initials: EK
authors.lastname: Kong
authors.forename: Ludmila
authors.initials: L
authors.lastname: Prokunina-Olsson
authors.forename: Wilfred Hing-Sang
authors.initials: WH
authors.lastname: Wong
authors.forename: Chak-Sing
authors.initials: CS
authors.lastname: Lau
authors.forename: Tak-Mao
authors.initials: TM
authors.lastname: Chan
authors.forename: Marta
authors.initials: M
authors.lastname: Alarcón-Riquelme
authors.forename: Yu-Lung
authors.initials: YL
authors.lastname: Lau
mesh_terms: D000328:Adult; D015703:Antigens, CD; D000954:Antigens, Surface / Q000235:genetics*; D051017:Apoptosis Regulatory Proteins; D001172:Arthritis, Rheumatoid / Q000208:ethnology / Q000235:genetics*; D002681:China / Q000208:ethnology; D005260:Female; D020022:Genetic Predisposition to Disease; D006239:Haplotypes / Q000235:genetics*; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D061026:Programmed Cell Death 1 Receptor; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015703:Antigens, CD; D000954:Antigens, Surface; D051017:Apoptosis Regulatory Proteins; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor