Association of the osteoprotegerin gene polymorphisms with bone mineral density in postmenopausal women

OBJECTIVES: Osteoprotegerin (OPG) is a recently discovered member of the tumour necrosis factor receptor superfamily. It plays a crucial role in the control of bone resorption and its gene could therefore be a good candidate gene for osteoporosis. The aim of our work was to find polymorphisms in the OPG gene and to investigate their possible contribution to the genetic susceptibility to osteoporosis by testing for their association with bone mineral density (BMD). METHODS: The whole OPG gene coding region was screened for the presence of polymorphisms in a group of 60 osteoporotic women by single-strand conformation polymorphism analysis (SSCP) approach. Association of the discovered polymorphisms with bone mineral density was investigated in 136 Slovenian postmenopausal women. RESULTS: We detected eight OPG gene polymorphisms that were confirmed by direct DNA sequencing, deletion 4752_4753delCT and nucleotide substitutions 1181G>C, 1217C>T, 1284G>A, 4501C>T, 6893A>G, 6950A>C and 8738T>A. Nucleotide substitutions 1284G>A and 8738T>A have not been previously described. Polymorphisms 4752_4753delCT, 6893A>G and 6950A>C were in complete linkage and the same was true for 1217C>T and 4501C>T. The association with BMD was found only for polymorphism 1181G>C. Subjects with genotype 1181GG had significantly lower lumbar spine BMD than subjects displaying 1181GC. CONCLUSIONS: By our approach we detected eight polymorphisms in the OPG gene. According to our analysis polymorphism 1181G>C is associated with BMD and could therefore be considered as an element of genetic susceptibility to osteoporosis.