دانلود رایگان مقاله تعیین ژنتیکی نمره ترابکولار استخوان و تراکم مواد معدنی استخوان

SUMMARY

This study sought to estimate the extent of genetic influence on the variation in trabecular bone score (TBS). We found that genetic factors accounted for ~45% of variance in TBS, and that the co-variation between TBS and bone density is partially determined by genetic factors. Introduction: Trabecular bone score has emerged as an important predictor of fragility fracture, but factors underlying the individual differences in TBS have not been explored. In this study, we sought to determine the genetic contribution to the variation of TBS in the general population. Methods: The study included 556 women and 189 men from 265 families. The individuals aged 53 years (SD 11). We measured lumbar spine bone mineral density (BMD; Hologic Horizon) and then derived the TBS from the same Hologic scan where BMD was derived. A biometric model was applied to the data to partition the variance of TBS into two components: one due to additive genetic factors, and one due to environmental factors. The index of heritability was estimated as the ratio of genetic variance to total variance of a trait. Bivariate genetic analysis was conducted to estimate the genetic correlation between TBS and BMD measurements. Results: TBS was strongly correlated with lumbar spine BMD (r = 0.73; P b 0.001). On average TBS in men was higher than women, after adjusting age and height which are significantly associated with both TBS and lumbar spine BMD. The age and height adjusted index of heritability of TBS was 0.46 (95% CI, 0.39–0.54), which was not much different from that of LSBMD (0.44; 95% CI, 0.31–0.55). Moreover, the genetic correlation between TBS and LSBMD was 0.35 (95% CI, 0.21–0.46), between TBS and femoral neck BMD was 0.21 (95% CI, 0.10–0.33). Conclusions: Approximately 45% of the variance in TBS is under genetic influence, and this effect magnitude is similar to that of lumbar spine BMD. This finding provides a scientific justification for the search for specific genetic variants that may be associated with TBS and fracture risk.

4. Discussion

TBS has emerged as an independent predictor of fragility fracture, with the magnitude of association being equivalent to that of bone mineral density. However, etiological determinants of TBS have not been well documented. In this family based study, we have demonstrated that approximately 45% of the between-individual variance in TBS was determined by genetic factors, after adjusting for age, gender and height. Moreover, the about one third of the covariation between TBS and lumbar spine BMD was also genetically determined. To our knowledge, this is the first demonstration of the heritability of TBS, and it is thus difficult to put the present study's finding within context. However, the index of heritability of LSBMD in this study is lower than previous twin studies'. Classical twin sties [12,13] have typically shown that the index of heritability for lumbar spine BMD ranged between 75% and 92%. In this study, we found that the heritability was much lower (51%). This difference is somewhat expected, because it is well known that twin studies tend to over-estimate the effect of genetic factors of a trait [14]. In the classical twin model, the shared environmental factors are assumed to be equal between monozygotic and dizygotic twins, and as a result, the heritability is often higher than in siblings based studies.