A meta-analysis of the relationship between aspartic acid (D)-repeat polymorphisms in asporin and osteoarthritis susceptibility

Our aim was to determine whether asporin (ASPN) D-repeat polymorphisms are associated with susceptibility to osteoarthritis (OA). A meta-analysis was conducted to examine the association between the ASPN D14, D13, and D15 alleles and OA of the knee and hip in each ethnic group. In total, 9 studies from eight articles involving 4,417 OA patients and 3,403 controls were considered in the meta-analysis. Meta-analysis showed no association between OA and the ASPN allele coding for 14 D-repeats (D14) in the overall population (OR 1.161, 95% CI 0.934-1.444, p = 0.178). Stratification by ethnicity identified no association between the ASPN D14 allele and OA in Europeans or Asians (OR 1.035, 95% CI 0.914-1.173, p = 0.589; OR 1.537, 95% CI 0.899-2.626, p = 0.116), respectively. However, high heterogeneity was found in Asians (I² = 81.2, p = 0.001). Meta-analysis of OA by site showed no association between knee and hip OA and the ASPN D14 allele (OR 1.240, 95% CI 0.946-1.627, p = 0.119; OR 1.130, 95% CI 0.767-1.665, p = 0.537). Meta-analysis of D14 versus D13 allele showed the same pattern of OA association as the D14 allele. No association was found between the ASPN D13 and D15 alleles and risk of developing OA by meta-analysis (OR 0.942, 95% CI 0.840-1.056, p = 0.304; OR 1.050, 95% CI 0.956-1.154, p = 0.306), respectively. This meta-analysis shows that the ASPN D14, D13, and D15 alleles are not associated with the development of OA in Europeans and Asians. Thus, further study of this relationship is required in homogenous populations because of the heterogeneity of the ASPN D14 allele observed in Asians.