Investigation of the asporin gene polymorphism as a risk factor for knee osteoarthritis in Iran.

Osteoarthritis (OA) is a degenerative disease of the joints characterized by degradation of the hyaline articular cartilage and remodeling of the subchondral bone with sclerosis. The asporin (ASPN) gene encodes a cartilage extracellular protein belonging to the small leucine-rich proteoglycan family. Polymorphisms in the aspartic acid (D) repeat region in the second exon of this gene, which consist of GAT repeats, are associated with OA susceptibility. The D14 allele, which contains 14 D-repeats, is associated with increased OA susceptibility in the Japanese and the Han Chinese but is not an important factor in OA etiology among Caucasians, though the D15 allele is a risk allele for the Greek population. To examine the possibility of this controversial association, we explored the effect of ASPN on Iranians with knee OA. The D-repeat polymorphism was genotyped in 100 knee OA patients and 100 controls, and the allelic association of the D-repeat was examined. Our data suggest that the D15 allele could be considered a risk allele significant only for women (P = .045, odds ratio = 1.73, 95% confidence interval [CI] = 1.01-2.94) in the Iranian population. This association is in part similar to that found for the Greek population.