title: Association between GDF5 rs143383 polymorphism and knee osteoarthritis: an updated meta-analysis based on 23,995 subjects.
abstract: BACKGROUND
  Previous studies investigating the association between GDF5 rs143383 polymorphism and knee osteoarthritis (OA) have suggested stronger associations in Asians than Caucasians, but limitations on the amount of available data have meant that a definitive assessment has not been possible. Given the availability of more recent data, the aim of this meta-analysis was to determine the overall association between GDF5 rs143383 polymorphism and knee OA and whether the association varies by ethnicity.
  
  
  METHODS
  Searches of Medline, Embase, and ISI Web of Science were conducted up to July 2013. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to estimate the strength of association between the GDF5 polymorphism and knee OA risk.
  
  
  RESULTS
  A total of 20 studies with 23,995 individuals were included. There were weak but significant associations present between the GDF5 polymorphism and knee OA at the allele level (C vs. T: OR =0.85, 95% CI = 0.80-0.90) and genotype level (CC vs. TT: OR = 0.73; CT vs. TT: OR = 0.84; CC/CT vs. TT: OR = 0.81; CC vs.
  OR = 0.81) in the overall population. In the subgroup analysis by ethnicity, we observed a strong significant association (OR = 0.60 to 0.80, all P <0.05) in Asian population and weaker associations (OR =0.78 to 0.87, all P <0.05) in Caucasian population; however marked heterogeneity was detected in all models except for CC vs. TT (I2 = 12.9%) and CC vs. CT + TT (I2 = 0.0%) in Asians.
  
  
  CONCLUSIONS
  These results strongly suggest that the C allele and CC genotype of the GDF5 gene are protective for knee OA susceptibility across different populations.
authors.affiliation: Menzies Research Institute Tasmania, University of Tasmania, Private Bag 23, Hobart, Tasmania 7000, Australia. Feng.Pan@utas.edu.au.
authors.forename: Feng
authors.initials: F
authors.lastname: Pan
authors.forename: Jing
authors.initials: J
authors.lastname: Tian
authors.forename: Tania
authors.initials: T
authors.lastname: Winzenberg
authors.forename: Changhai
authors.initials: C
authors.lastname: Ding
authors.forename: Graeme
authors.initials: G
authors.lastname: Jones
mesh_terms: D056726:Genetic Association Studies / Q000379:methods*; D020022:Genetic Predisposition to Disease / Q000453:epidemiology / Q000235:genetics*; D055428:Growth Differentiation Factor 5 / Q000235:genetics*; D006801:Humans; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*
chemical_list: C525893:GDF5 protein, human; D055428:Growth Differentiation Factor 5