Aspartic acid repeat polymorphism of the Asporin gene with susceptibility to osteoarthritis of the knee in a Korean population

Osteoarthritis (OA) is a common disease that is characterized by the degeneration of joint cartilage in the knee, hip and hand. Recently, it has been reported that susceptibility to OA is affected by the number of aspartic acid (D) residues in the amino-terminal of the asporin protein. In order to investigate whether the association found in Japanese OA is also present in the Korean population, the frequency of the polymorphism was examined in 190 OA patients and 376 healthy controls. The D-repeat microsatellite polymorphism was examined by amplifying the asporin gene and sequencing its products. The frequencies of the D13 and D14 alleles were 69.7% (265/380) and 5.8% (22/380), respectively, in OA patients and 64.2% (483/752) and 8.7% (65/752), respectively, in healthy controls. When we adjusted for gender and age, there was no statistically significant difference between Korean OA patients and healthy controls (P = 0.1082) in the allele frequency of D13 compared to the other alleles. However, a significant difference between female OA patients and their controls (P = 0.0245) in the allele frequency of the D13 allele was found compared to the other alleles. There was no significant difference between Korean OA patients and healthy controls in the frequency of the D14 and other alleles (P = 0.2339). These results suggest that asporin may play a role in OA susceptibility of the knee in the Korean female population.