Eta-1/osteopontin genetic polymorphism is associated with urolithiasis in Koreans

Abstract

Purpose: Osteopontin (OPN) is one of the major non-collagenous bone matrix proteins produced by osteoblasts and osteolclasts, and it is also involved in the pathogenesis of urolithiasis. Single nucleotide polymorphisms (SNPs), as a tool for searching for the genetic markers of disease, have a large role in investigating the genetic markers of complex human diseases. The aim of this study is to investigate the association with this SNP at position nucleotide 9250 (C→T) in the OPN gene and the susceptibility to urolithiasis. We also compared the allele frequency of Koreans with those of Americans and Japanese. Materials and Methods: A total of 161 urolithiasis patients and 104 healthy controls were studied. The SNPs located at position 9520 in the OPN gene were genotyped using restriction fragment length polymorphism (RFLP). The wild-type sequence contains a C while the polymorphism variant is a T (C→T), which results in the appearance of an Alu I restriction site. Results: The gene frequencies of C/C, C/T and T/T at position 9250 on the Eta-1/osteopontin gene in urolithiasis patients were 10.6%, 36.6% and 52.8%, respectively, compared with 6.7%, 27.9% and 65.8%, respectively, in the controls (p>0.05). The allele frequencies of C and T at this position in the urolithiasis patients were 28.9 and 72.1, respectively, whereas those in the controls were 20.7 and 79.3, respectively, (p<0.05). The allele frequencies found in the present study were compared with those coding SNPs described in the USA database; 60 and 39 (USA) vs 20.7 and 79.3 (Korea), respectively (p<0.05). Conclusions: Those findings suggest there is no association of with Eta-1/osteopontin genetic polymorphism, but the allele frequencies were significantly associated with urolithiasis patients. We also observed difference of allele frequencies in our controls and in the USA controls and these differences may be caused by a difference in the incidence of urolithiasis patients between the two countries.