Serum osteoprotegerin (OPG) and the A163G polymorphism in the OPG promoter region are related to peripheral measures of bone mass and fracture odds ratios.

Abstract

The purpose of this study is to investigate the association of serum osteoprotegerin (OPG) and the A163G polymorphism in the OPG promoter with peripheral measures of bone mass and with odds ratios for wrist and hip fracture in a case-control study of postmenopausal Danish women. The study included 66 women with lower forearm fracture, 41 women with hip fracture, and 206 age-matched controls. All had broadband ultrasound attenuation (BUA) and speed of sound (SOS) measured at the heel as well as bone mineral density (BMD) measured by DXA at the distal forearm. S-OPG was measured by ELISA. The A163G genotypes were determined by PCR-RFLP analysis. S-OPG levels correlated positively with age ( r = 0.45; P << 0.0001) and negatively with distal forearm BMD ( r = -0.31; P << 0.0001), heel BUA ( r = -0.23; P << 0.0001), and heel SOS ( r = -0.22; P << 0.0001). Comparing the highest quartile of S-OPG to the lowest, the odds ratio for osteoporotic fracture was 2.5 (95% CI, 1.3-4.7; P = 0.006). The G allele of the A163G was associated with significantly lower t-scores of both lower forearm BMD, heel BUA, and heel SOS as well as being significantly more frequent in the fracture patients compared to the controls. Patients with a combination of the highest quartile of S-OPG and presence of the G allele ( n = 23) had a significantly elevated fracture odds ratio, 4.0 (95% CI, 1.7-9.9). A significant negative association between S-OPG with peripheral measures of bone mass and with increased fracture odds ratios was found. Furthermore, the A163G mutation in the OPG promoter had a significant influence on bone mass and fracture status independently of S-OPG level.