Abstract: 【Abstract】 Objective To investigate the effect of polymorphisms of T149C and T950C in the promoter region of osteoprotegerin (OPG) gene on bone mineral density (BMD) in patients treated with glucocorticoids. Methods We determined T149C and T950C polymorphisms in the promoter region of OPG gene by PCR-RFLP in 208 healthy individuals (group 1) and 272 patients treated with large doses of glucocorticoids (group 2). BMD at lumbar spine, femoral neck, trochanter and Ward’s triangle were measured by dual-energy X-ray absorptiometry (DEXA). Several markers relating to bone turnover were also assayed. Results Hardy-Weinberg equilibrium was evident to the two polymorphisms. T149C genotypes in group 1 were TT (81.75%), TC (16.67%) and CC (1.58%), and those in group 2 were TT (82.61%), TC (15.94%) and CC (1.45%). There is no significant difference in the distribution of T149C genotypes between the two groups (P>0.05). T950C genotypes in group 1 were TT (26.98%), TC (48.41%) and CC (24.61%), those in group 2 were TT (27.54%), TC (48.55%) and CC (23.91%). There is also no significant difference in the distribution of T950C genotypes between the two groups (p>0.05). In group 2, however, BMD at femoral neck area was 0.91 + 0.06 g/cm2 and 0.87 + 0.08g/cm2 in patients carrying TT and TC+CC of the T149C genotype, respectively (P<0.05 by ANOVA). This difference is still significant after adjustment by age and body weight index. In group 2, the correlation of T950C genotypes to the magnitude of BMD at all areas was CC＞TC＞TT, but this correlation is statistically insignificant (P>0.05). In group I, no correlation of the genotypes T149C and T950C to the magnitude of BMD was observed. Conclusions There are no differences in the distribution of T149C and T950C genotypes in OPG gene between the two groups. Therefore, these two polymorphisms may not be related to the pathogenesis of glomerulonephritis. The polymorphism T149C may relate to the BMD at femoral neck in patients treated with glucocorticoids, in which allele T may be the protection factor of bone mass and may involve in the loss of bone mass by glucocorticoids. The polymorphism T950C may have no effects on BMD at all areas, and may not involve in the loss of bone mass by glucocorticoids.

Key words: Single nucleotide polymomphism, Glucocorticoids, Bone mineral density