title: Meta-analysis of the association between COL9A2 genetic polymorphisms and lumbar disc disease susceptibility.
abstract: METHODS
  Meta-analysis to collect all the relevant studies to date to further investigate whether or not the COL9A2 gene rs12077871, rs12722877, and rs7533552 polymorphism are associated with susceptibility to lumbar disc disease (LDD).
  
  
  OBJECTIVE
  The aim of this study was to assess the association between the COL9A2 gene rs12077871, rs12722877, and rs7533552 and LDD.
  
  
  BACKGROUND
  LDD is a common musculoskeletal disease with strong genetic determinants. COL9A2 encodes the α2 (IX) chain of type IX collagen, which is the major collagen component of the hyaline cartilage. Growing numbers of studies have revealed the association between COL9A2 polymorphisms and susceptibility to LDD. However, those studies have yielded contradictory results.
  
  
  METHODS
  Data were collected from the following electronic databases: PubMed, Web of Knowledge, and China National Knowledge Infrastructure, with the last report up to November 30, 2013. The odds ratio (OR) and 95% confidence interval (CI) were used to assess the strength of association under the allelic genetic model. We summarized the data on the association between COL9A2 rs12077871, rs12722877, and rs7533552 polymorphism and LDD in the overall studies.
  
  
  RESULTS
  Nine case-control studies, including 1522 LDD cases and 1646 controls, were identified. The results indicated that the rs12077871, rs12722877, and rs7533552 variants in COL9A2 were not associated with LDD (rs12077871: C vs. T, OR = 0.541, 95% CI = 0.256-1.147, P = 0.109; rs12722877: C vs. G, OR = 1.199, 95% CI = 0.992-1.448, P = 0.06; rs7533552: A vs. G, OR = 0.993, 95% CI = 0.815-1.069, P = 0.320). Furthermore, the Egger test and the Begg funnel plot did not show any evidence of publication bias.
  
  
  CONCLUSIONS
  Our results suggest that the COL9A2 rs12077871, rs12722877, and rs7533552 polymorphisms may not be associated with LDD. More studies based on larger sample sizes and homogeneous samples of patients with LDD are needed to confirm these findings.
  
  
  METHODS
  2.
authors.affiliation: From the Department of Orthopedics, Taizhou Central Hospital, Taizhou, Zhejiang Province, China.
authors.forename: Zhaobo
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jingsheng
authors.initials: J
authors.lastname: Zhang
authors.forename: Lingzhi
authors.initials: L
authors.lastname: Ding
authors.forename: Xiao
authors.initials: X
authors.lastname: Teng
mesh_terms: D000483:Alleles; D024081:Collagen Type IX / Q000235:genetics*; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D006801:Humans; D055959:Intervertebral Disc Degeneration / Q000235:genetics* / Q000473:pathology; D008159:Lumbar Vertebrae / Q000473:pathology*; D020641:Polymorphism, Single Nucleotide
chemical_list: C120282:COL9A2 protein, human; D024081:Collagen Type IX