Relationship between the gene polymorphism of osteoprotegerin and bone mineral density in hemodialysis patients.

ABSTRACT

OBJECTIVE: To investigate the relationship between the gene polymorphism of osteoprotegerin (OPG) and bone mineral density (BMD) in hemodialysis patients. PATIENTS AND METHODS: A total of 147 patients with end-stage renal disease (ESRD) who were admitted to the Weifang People's Hospital for maintenance hemodialysis between January 2014 and December 2015 were enrolled. Peripheral blood was collected from the subjects for assay of the polymorphism of A163G and G1181C loci of OPG. The measurements of the levels of RANK, RANKL, TNF-α, IL-6, PINP, CTX-I, CTX-II and TRACP5 in the isolated serum were taken. RESULTS: For the polymorphism of A163G locus on the OPG gene, the BMDs of left femoral neck and lumbar poster anterior L1-L4 of the AA genotype were significantly higher than those of the AG and GG genotypes. There was no significant difference in comparison of BMDs at the forearm (distal 1/3) between the AA genotype and AG and GG genotypes. No significant differences were found in the comparison of BMDs at all sites between AG and GG genotypes. The serum level of RANKL of the AA genotype was significantly higher than levels of AG and GG genotypes, but the levels of RANK, TNF-α, IL-6, PINP, CTX-I, CTX-II and TRACP5 were prominently lower than those levels of AG and GG genotypes. For the polymorphism of G1181C locus on the OPG gene, the BMDs of left femoral neck and lumbar poster anterior L1-L4 of the CC genotype were significantly higher than the BMDs of GG and GC genotypes, There was no significant difference in the comparison of BMDs at the forearm (distal 1/3) between the CC genotype and GG and GC genotypes. No significant differences were found in the comparison of BMDs at all sites between GG and GC genotypes. The serum level of RANKL of the CC genotype was significantly higher than the level of GG and GC genotypes. However, the levels of RANK, TNF-α, IL-6, PINP, CTX-I, CTX-II and TRACP5 were prominently lower than those levels of GG and GC genotypes. CONCLUSIONS: The polymorphisms of A163G and G1181C loci on the OPG gene were correlated with the BMD of hemodialysis patients. The genotype AA of A163G and genotype CC of G1181C were identified as the protective factors for BMD.