Genotypes and clinical aspects associated with bone mineral density in Argentine postmenopausal women

Association between the ESR1 and ESR2 polymorphisms and osteoporosis risk: An updated meta-analysis

BACKGROUND

Gene polymorphisms of estrogen receptor (ESR) 1 PvuII (rs2234693), XbaI (rs9340799), G2014A (rs2228480), ESR2 AluI (rs4986938), and RsaI (rs1256049) had been reported to be associated with the risk of osteoporosis. However, these conclusions were inconsistent, therefore, an updated meta-analysis was conducted to further explore these issues.

OBJECTIVE

To evaluate the association between gene polymorphisms of ESR1 PvuII (rs2234693), XbaI (rs9340799), G2014A (rs2228480), ESR2 AluI (rs4986938), RsaI (rs1256049), and osteoporosis risk.

MATERIALS AND METHODS

PubMed, Medline, Ovid, Embase, CNKI, and China Wanfang databases were searched. Association was assessed using odds ratio with 95% confidence interval. Moreover, the false-positive reporting probability, Bayesian false-finding probability, and Venetian criteria were used to assess the credibility of statistically significant associations.

RESULTS

Overall, ESR1 PvuII (rs2234693) and XbaI (rs9340799) were associated with the risk of osteoporosis in Indians. Moreover, ESR1 G2014A (rs2228480) was associated with the decreased risk of osteoporosis in East Asians. Moreover, ESR2 Alul (rs4986938) was associated with the increased risk of osteoporosis in East Asians and Caucasians. There was a significant association between ESR2 Rsal (rs1256049) and osteoporosis risk in overall population. When only high-quality and Hardy-Weinberg equilibrium studies were included in the sensitivity analysis, all results did not change in the present study. When the credibility was evaluated applying false-positive reporting probability, Bayesian false-finding probability, and Venetian criteria, all significant associations were considered as false positive results.

CONCLUSIONS

In summary, this study shows that all substantial associations between gene polymorphisms of ESR1 (PvuII, XbaI, and G2014A) and ESR 2 (AluI and RsaI) and osteoporosis risk are possibly false positive results instead of real associations or biological variables.

Association of ESR1 and ESR2 Polymorphisms with Osteoporosis: A Meta-Analysis from 36 Studies

BACKGROUND

Recently, the roles of ESR1 and ESR2 polymorphisms in osteoporosis have been extensively reported, with conflicting findings. Therefore, we performed this present study to evaluate the potential associations between ESR1 and ESR2 polymorphisms and osteoporosis risk.

METHODOLOGY

All included literatures published up to April 2021 were identified by searching Pubmed, Embase, Web of Science, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI) and Wanfang databases. Pooled odds ratio (OR) and 95% confidence interval (CI) were calculated the associations using a fixed or random effects model.

RESULTS

36 observational studies involving five gene polymorphisms (ESR1 PvuII, ESR1 XbaI, ESR1 G2014A, ESR2 AluI and ESR2 RsaI) covering 12507 cases and 18487 controls were included. The results of our meta-analysis demonstrated the variant A allele of ESR2 RsaI polymorphism might play a remarkable protective role in developing osteoporosis under all genetic models. However, no associations were observed between ESR1 PvuII, ESR1 XbaI, ESR1 G2014A and ESR2 AluI polymorphisms with the risk of osteoporosis under all genetic models.

CONCLUSIONS

Our meta-analysis suggests that genetic polymorphism in ESR2 RsaI may lead to decreased risk for osteoporosis. Further larger studies are needed to confirm this conclusion.

Relationship Between Vitamin D Receptor Gene BsmI Polymorphism and Fibromyalgia Syndrome

Purpose

Vitamin D receptor (VDR) has been proposed as a possible marker for fibromyalgia syndrome (FMS). The purpose of this study is to characterize the expression pattern of BsmI polymorphism (rs1544410) in the VDR gene in women with FMS and the genotype-phenotype association.

Methods

A total of 105 FMS patients and 105 controls were included in this study. VDR gene BsmI polymorphism was assessed by polymerase chain reaction (PCR) and restriction fragment length polymerase (RFLP) method.

Results

There was no significant difference in the frequency distribution of both genotypes and alleles for VDR gene BsmI polymorphism between FMS patients and controls (p>0.05). The frequencies of BB, Bb, and bb in the VDR gene BsmI polymorphism were 19%, 43%, and 37% in patients, while in controls were 22.9%, 55.2%, and 21.9%. However, we did not find any significant association between the clinical symptoms of this disease and VDR BsmI genotypes among FMS patients (p>0.05).

Conclusions

The relationship between the VDR gene BsmI polymorphism and FMS could not be determined in this study. However, further studies with a larger sample size may be required to show a relation between the VDR gene BsmI polymorphism and FMS.

Vitamin D receptor Bsm I polymorphism and osteoporosis risk in postmenopausal women: a meta-analysis from 42 studies

OBJECTIVE

This study aimed to quantitatively summarize the evidence for VDR BsmI gene polymorphism and osteoporosis risk in postmenopausal women.

MATERIALS AND METHODS

The PubMed, EMBASE, Weipu, CNKI, and Wanfang databases were searched for eligible studies. Case-control studies containing available genotype frequencies of B/b were chosen, and odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of this association.

RESULTS

4485 osteoporosis and 5490 controls were identified in our meta-analysis. In the stratified analysis, a significant association was observed between VDR BsmI gene polymorphism and osteoporosis susceptibility in Caucasians (additive model: OR = 0.809, 95% CI 0.678~0.965, p = 0.019; recessive model: OR = 0.736, 95% CI 0.568~0.955, p = 0.021; and co-dominant model: bb vs. BB OR = 0.701, 95% CI 0.511~0.962 p = 0.028), and we failed to find any significant relationship in Asians.

CONCLUSION

The present meta-analysis suggests that VDR BsmI genotype is associated with increased risk of postmenopausal osteoporosis in Caucasians but not in Asians. To draw comprehensive and true conclusions, further prospective studies with larger numbers of participants worldwide are needed to examine associations between VDR BsmI polymorphism and osteoporosis in postmenopausal women.

Association between vitamin D receptor BsmI, FokI, and Cdx2 polymorphisms and osteoporosis risk: an updated meta-analysis

Background: Many studies have reported the association between vitamin D receptor (VDR) polymorphism and osteoporosis risk. However, their results were conflicting. Six previous meta-analyses have been published to analyze VDR BsmI, FokI, and Cdx2 polymorphisms on osteoporosis risk. However, they did not evaluate the reliability of statistically significant associations. Furthermore, a lot of new articles have been published on these themes, and therefore an updated meta-analysis was performed to further explore these issues.

Objectives: To explore the association between VDR BsmI, FokI, and Cdx2 polymorphisms polymorphisms and osteoporosis risk.

Methods: The odds ratios (ORs) and 95% confidence intervals (95% CIs) were pooled to evaluate the association between VDR BsmI, FokI, and Cdx2 polymorphisms and osteoporosis risk. To evaluate the credibility of statistically significant associations, we applied the false-positive report probabilities (FPRPs) test and the Venice criteria.

Results: Overall, statistically significantly increased osteoporosis risk was found in Indians and women for VDR FokI polymorphism. Statistically significantly decreased osteoporosis risk was found in West Asians for VDR BsmI polymorphism. However, when we performed a sensitivity analysis after excluding low quality and Hardy–Weinberg Disequilibrium (HWD) studies, significantly decreased osteoporosis risk was only found in overall population for VDR BsmI polymorphism. Further, less-credible positive results were identified when we evaluated the credibility of positive results.

Conclusion: These positive findings should be interpreted with caution and indicate that significant association may most likely result from less-credible, rather than from true associations or biological factors on the VDR BsmI and FokI polymorphisms with osteoporosis risk.

The association between vitamin D receptor FokI gene polymorphism and osteoporosis in postmenopausal women: a meta-analysis

OBJECTIVE

This study aimed to quantitatively summarize the evidence for vitamin D receptor (VDR) FokI gene polymorphism and osteoporosis risk in Caucasian and Asian postmenopausal women.

MATERIALS AND METHODS

The PubMed, EMBASE, Weipu, CNKI, and Wanfang databases were searched for eligible studies. Case-control studies containing available genotype frequencies for F/f were chosen, and the odds ratio (OR) with 95% confidence interval (CI) was used to assess the strength of this association.

RESULTS

In total, 3349 osteoporosis cases and 3202 controls were identified in our meta-analysis. In the stratified analysis, a significant association was observed between VDR FokI gene polymorphism and postmenopausal osteoporosis susceptibility in Asian subjects (additive model: OR = 1.529, 95% CI 1.053-2.219, p = 0.026; dominant model: OR 2.711, 95% CI 1.693-4.342 p < 0.001; co-dominant model: ff vs. FF, OR 2.796, 95% CI 1.439-5.433 p = 0.002), and we failed to find any significant relationship in Caucasian populations.

CONCLUSION

The present meta-analysis suggests that the VDR FokI genotype is associated with increased risk of osteoporosis in Asian women but not in Caucasian women. To draw comprehensive and true conclusions, further prospective studies with larger numbers of participants worldwide are needed to examine associations between VDR FokI polymorphism and osteoporosis.

Vitamin D receptor (VDR) gene FokI, BsmI, ApaI, and TaqI polymorphisms and osteoporosis risk: a meta-analysis

Background

Osteoporosis is a disease of the bones in which the density of the bones decreases. The prevalence of this disease greatly varies in different populations of the world. Numerous studies have been investigated VDR gene polymorphisms as osteoporosis risk in different ethnic groups. In present meta-analysis, the aim is to find out the role of VDR gene polymorphisms (FokI, BsmI, ApaI, and TaqI) in osteoporosis risk.

Methods

Suitable case-control studies for present meta-analysis were retrieved from four electronic databases. Open Meta-Analyst program was used for statistical analyses.

Results

Studies investigated BsmI (65 studies; 6880 cases/8049 controls), ApaI (31 studies; 3763 cases/3934 controls), FokI (18 studies; 1895 cases/1722 controls), and TaqI (26 studies; 2458 cases/2895 controls) polymorphisms that were included in the present meta-analysis. A significant association was found between the dominant model of FokI (ORff + Ffvs.FF = 1.19, 95% CI = 1.04–1.36, p = 0.01, I2 = 39.36%) in the overall analysis and recessive model of the Caucasian population of TaqI polymorphism (ORTT + Ttvs.tt = 1.35, 95% CI = 1.11–1.63, p = 0.002, I2 = 50.07%) with osteoporosis. On the other hand, no such effect is found in any other genetic models and in any other gene polymorphisms of the overall analyses or sub-group analyses.

Conclusion

In conclusion, the authors found that the dominant model of FokI in the overall analysis and recessive model of TaqI in the Caucasian population are significantly associated with the development of osteoporosis.

Association of Vitamin D Receptor (FokI and BsmI) Gene Polymorphism with Bone Mineral Density and Their Effect on 25-Hydroxyvitamin D Level in North Indian Postmenopausal Women with Osteoporosis

Osteoporosis is a systemic disease with a strong genetic component. Vitamin D receptor (VDR) has been suggested as a candidate gene for osteoporosis. Therefore the present study was aimed to investigate the pattern of allelic variants of VDR gene polymorphism (FokI and BsmI), its influence on vitamin D levels and bone mineral density (BMD) in North Indian postmenopausal women with osteoporosis for possible genetic association. 254 postmenopausal osteoporotic women and 254 postmenopausal non osteoporotic women were included in the study. VDR FokI and BsmI gene polymorphism gene were assessed by the PCR-RFLP method. Serum 25-hydroxyvitamin D was measured by the ELISA. BMD at the L1-L4 lumbar spine, hip, forearm and femoral neck was assessed by dual energy X-ray absorptiometry. The average BMD at spine and hip in postmenopausal women with bb and spine, hip, femoral neck and forearm with ff genotype had significantly low BMD. The frequency of ff genotype and f allele was significantly higher in postmenopausal osteoporotic women when compared with postmenopausal non osteoporotic women. However, no significant association was found between the genotypes and vitamin D levels. Our study reveals that VDR gene FokI and BsmI polymorphism is significantly associated with low bone mineral density. Therefore the ff genotype and f allele of VDR FokI gene may be used as an important risk factor for osteoporosis.

Associations between ERα/β gene polymorphisms and osteoporosis susceptibility and bone mineral density in postmenopausal women: a systematic review and meta-analysis

BACKGROUND

Many studies have reported associations between estrogen receptor (ER) gene polymorphisms and postmenopausal osteoporosis (PMOP) risk and bone mineral density (BMD), but the results are controversial. The aim of the present meta-analysis is to verify the association between ERα and ERβ gene polymorphisms and osteoporosis susceptibility and BMD in postmenopausal women.

METHODS

PubMed, EMBASE, Web of Science, the Cochrane Library and China WeiPu Library were searched. OR and WMD with 95% CI were calculated to assess the association.

RESULTS

Overall, no significant association was observed between ERα XbaI, ERα PvuII and PMOP susceptibility in either overall, Caucasian or Asian populations. ERα G2014A was significantly associated with a decreased risk of PMOP in Caucasian populations. There was a significant association between ERβ RsaI and PMOP risk in both overall and Asian populations. Caucasian PMOP women with ERα XbaI XX and Xx genotypes had a higher LS Z value than women with xx genotype. ERα XbaI XX genotype was associated with increased FN BMD in overall and Caucasian populations, an increased FN Z value in Asians, and a decreased FN Z value in Caucasians. There was also a significant association between ERα XbaI Xx genotype and an increased FN Z value in either Asians or Caucasians. ERα PvuII PP genotype was associated with a low LS Z value in Caucasians and a low FN BMD and Z value in Asians. Pp genotype in PMOP women was significantly correlated with low LS BMD in overall populations, a low FN Z value in either overall, Caucasian or Asian populations.

CONCLUSION

Each ERα and ERβ gene polymorphism might have different impact on PMOP risk and BMD in various ethnicities.

Associations between VDR Gene Polymorphisms and Osteoporosis Risk and Bone Mineral Density in Postmenopausal Women: A systematic review and Meta-Analysis

Results on the relationships between vitamin D receptor (VDR) gene polymorphisms and postmenopausal osteoporosis (PMOP) susceptibility and bone mineral density (BMD) are conflicting. The aim of the study is to identify more eligible studies that calculated pooled OR and WMD with 95% CI to assess their associations. Overall, there were significant correlations between VDR ApaI, VDR FokI and PMOP susceptibility. Subgroup analysis showed that VDR ApaI polymorphism significantly decreased the osteoporosis risk in Caucasian postmenopausal women. In Asian populations, VDR BsmI and VDR FokI were associated with an increased risk of PMOP. As to the associations between VDR polymorphisms and BMD, Caucasian PMOP women carrying the ApaI aa genotype were at risk of high BMD in femoral neck, and low femoral neck BMD was observed in Caucasian PMOP women with FokI Ff genotype. PMOP women with the Cdx2 GA genotype had a lower lumbar spine BMD in overall and Caucasian populations compared with PMOP women with GG genotype. Different VDR gene polymorphisms have different impacts on PMOP risk and BMD.

Genetic Dissection of Trabecular Bone Structure with Mouse Intersubspecific Consomic Strains

Trabecular bone structure has an important influence on bone strength, but little is known about its genetic regulation. To elucidate the genetic factor(s) regulating trabecular bone structure, we compared the trabecular bone structures of two genetically remote mouse strains, C57BL/6J and Japanese wild mouse-derived MSM/Ms. Phenotyping by X-ray micro-CT revealed that MSM/Ms has structurally more fragile trabecular bone than C57BL/6J. Toward identification of genetic determinants for the difference in fragility of trabecular bone between the two mouse strains, we employed phenotype screening of consomic mouse strains in which each C57BL/6J chromosome is substituted by its counterpart from MSM/Ms. The results showed that many chromosomes affect trabecular bone structure, and that the consomic strain B6-Chr15^MSM, carrying MSM/Ms-derived chromosome 15 (Chr15), has the lowest values for the parameters BV/TV, Tb.N, and Conn.D, and the highest values for the parameters Tb.Sp and SMI. Subsequent phenotyping of subconsomic strains for Chr15 mapped four novel trabecular bone structure-related QTL (Tbsq1-4) on mouse Chr15. These results collectively indicate that genetic regulation of trabecular bone structure is highly complex, and that even in the single Chr15, the combined action of the four Tbsqs controls the fragility of trabecular bone. Given that Tbsq4 is syntenic to human Chr 12q12-13.3, where several bone-related SNPs are assigned, further study of Tbsq4 should facilitate our understanding of the genetic regulation of bone formation in humans.

Analysis of SNP-SNP interactions and bone quantitative ultrasound parameter in early adulthood

Background

Osteoporosis individual susceptibility is determined by the interaction of multiple genetic variants and environmental factors. The aim of this study was to conduct SNP-SNP interaction analyses in candidate genes influencing heel quantitative ultrasound (QUS) parameter in early adulthood to identify novel insights into the mechanism of disease.

Methods

The study population included 575 healthy subjects (mean age 20.41; SD 2.36). To assess bone mass QUS was performed to determine Broadband ultrasound attenuation (BUA, dB/MHz). A total of 32 SNPs mapping to loci that have been characterized as genetic markers for QUS and/or BMD parameters were selected as genetic markers in this study. The association of all possible SNP pairs with QUS was assessed by linear regression and a SNP-SNP interaction was defined as a significant departure from additive effects.

Results

The pairwise SNP-SNP analysis showed multiple interactions. The interaction comprising SNPs rs9340799 and rs3736228 that map in the ESR1 and LRP5 genes respectively, revealed the lowest p value after adjusting for confounding factors (p-value = 0.001, β (95% CI) = 14.289 (5.548, 23.029). In addition, our model reported others such as TMEM135-WNT16 (p = 0.007, β(95%CI) = 9.101 (2.498, 15.704), ESR1-DKK1 (p = 0.012, β(95%CI) = 13.641 (2.959, 24.322) or OPG-LRP5 (p = 0.012, β(95%CI) = 8.724 (1.936, 15.512). However, none of the detected interactions remain significant considering the Bonferroni significance threshold for multiple testing (p<0.0001).

Conclusion

Our analysis of SNP-SNP interaction in candidate genes of QUS in Caucasian young adults reveal several interactions, especially between ESR1 and LRP5 genes, that did not reach statistical significance. Although our results do not support a relevant genetic contribution of SNP-SNP epistatic interactions to QUS in young adults, further studies in larger independent populations would be necessary to support these preliminary findings.

Influence of vitamin D and estrogen receptor gene polymorphisms on calcium absorption: BsmI predicts a greater decrease during energy restriction

Low calcium absorption is associated with low bone mass and fracture. In this study, we use gold standard methods of fractional calcium absorption (FCA) to determine whether polymorphisms of intestinal receptors, vitamin D receptor (VDR) and estrogen receptor α (ESR1), influence the response to energy restriction. Fractional calcium absorption was measured using dual stable isotopes ((42)Ca and (43)Ca) in women given adequate calcium and vitamin D and examined at baseline and after 6 weeks of energy restriction or no intervention. After genotyping, the relationship between VDR and ESR1 genotypes/haplotypes and FCA response was assessed using several genetic models. One-hundred and sixty-eight women (53 ± 11 years of age) were included in this analysis. The ESR1 polymorphisms, PvuII and XbaI and VDR polymorphisms (TaqI, ApaI) did not significantly influence FCA. The BB genotype of the VDR polymorphism, BsmI, was associated with a greater decrease in FCA than the Bb/bb genotype. Multiple linear regression showed that the BsmI polymorphism or the VDR haplotype, BAt, in addition to changes in weight and vitamin D intake explained ~16% of the variation in changes in FCA. In conclusion, the reduction in calcium absorption due to energy restriction is greatest for those with the BB genotype. Previous candidate gene studies show that VDR polymorphisms are associated with higher risk for osteoporosis, and the current study supports the notion that the BsmI polymorphism in intestinal VDR may be contributing to alterations in bone health.

Association between vitamin D receptor gene polymorphisms (Fok1 and Bsm1) and osteoporosis: a systematic review

Osteoporosis is a health concern characterized by reduced bone mineral density (BMD) and increased risk of fragility fractures. Many studies have investigated the association between genetic variants and osteoporosis. Polymorphism and allelic variations in the vitamin D receptor gene (VDR) have been found to be associated with bone mineral density. However, many studies have not been able to find this association. Literature review was conducted in several databases, including MEDLINE/Pubmed, Scopus, EMBASE, Ebsco, Science Citation Index Expanded, Ovid, Google Scholar, Iran Medex, Magiran and Scientific Information Database (SID) for papers published between 2000 and 2013 describing the association between Fok1 and Bsm1 polymorphisms of the VDR gene and osteoporosis risk. The majority of the revealed papers were conducted on postmenopausal women. Also, more than 50% studies reported significant relation between Fok1, Bsm1 and osteoporosis. Larger and more rigorous analytical studies with consideration of gene-gene and gene-environment interactions are needed to further dissect the mechanisms by which VDR polymorphisms influence osteoporosis.

Vitamin D receptor Fok I polymorphism is associated with low bone mineral density in postmenopausal women: a meta-analysis focused on populations in Asian countries

OBJECTIVE

To explore the associations between vitamin D receptor (VDR) gene polymorphisms (including Fok I, Bsm I and Apa I) and bone mineral density (BMD) in postmenopausal Asian women.

STUDY DESIGN

Databases of Medline, Embase and Wangfang were retrieved to identify eligible studies, with update to 1st February 2012. Standardized mean difference (SMD) and 95% confidence intervals were calculated by using fixed- or random-effect model. Best genetic comparison model was determined by using the Thakkinstian method.

RESULTS

A total of 14 studies with 3243 healthy postmenopausal Asian women were included in this meta-analysis. Overall, pooled analyses indicated that the f allele of VDR Fok I was significantly associated with decreased BMD in the lumbar spine (ff vs. FF: SMD (95% CI): -0.87 (-1.38, -0.35); P=0.001 for lumbar spine; -0.43 (-0.93, 0.06), P=0.086 for femoral neck). In contrast, we did not observe overall associations between VDR Bsm I and Apa I polymorphisms and BMD in either lumbar spine or femoral neck (Bsm I bb vs. BB: SMD (95% CI): 0.61 (-1.30, 2.53), P=0.531 for lumbar spine; Apa I aa vs. AA: SMD (95% CI): 0.66 (-0.16, 1.48), P=0.113 for lumbar spine). When subgroup analyses were conducted according to countries, Indians carrying the VDR Fok I ff genotype were at risk of low BMD at lumbar spine (ff vs. FF: SMD (95% CI): -0.57 (-0.85, -0.29), P<0.001). Sensitivity analyses indicated that no single study had substantial influence on all combined analyses. In addition, no publication bias was identified.

CONCLUSIONS

This meta-analysis indicated that VDR Fok I, rather than Bsm I and Apa I polymorphisms, is associated with bone mineral density in postmenopausal Asian women (especially for Indian women), and can probably be used with other genetic markers together to identify individuals at high risk of osteoporosis.

Gene-gene interaction between RBMS3 and ZNF516 influences bone mineral density

Osteoporosis is characterized by low bone mineral density (BMD), a highly heritable trait that is determined, in part, by the actions and interactions of multiple genes. Although an increasing number of genes have been identified to have independent effects on BMD, few studies have been performed to identify genes that interact with one another to affect BMD. In this study, we performed gene-gene interaction analyses in selected candidate genes in individuals with extremely high versus low hip BMD (20% tails of the distributions), in two independent U.S. Caucasian samples. The first sample contained 916 unrelated subjects with extreme hip BMD Z-scores selected from a population composed of 2286 subjects. The second sample consisted of 400 unrelated subjects with extreme hip BMD Z-scores selected from a population composed of 1000 subjects. Combining results from these two samples, we found one interacting gene pair (RBMS3 versus ZNF516) which, even after Bonferroni correction for multiple testing, showed consistently significant effects on hip BMD. RMBS3 harbored two single-nucleotide polymorphisms (SNPs), rs6549904 and rs7640046, both of which had significant interactions with an SNP, rs4891159, located on ZNF516 (p = 7.04 × 10(-11) and 1.03 × 10(-10) ). We further validated these results in two additional samples of Caucasian and African descent. The gene pair, RBMS3 versus ZNF516, was successfully replicated in the Caucasian sample (p = 8.07 × 10(-3) and 2.91 × 10(-3) ). For the African sample, a significant interaction was also detected (p = 0.031 and 0.043), but the direction of the effect was opposite to that observed in the three Caucasian samples. By providing evidence for genetic interactions underlying BMD, this study further delineates the genetic architecture of osteoporosis.

Estrogen receptor gene polymorphisms in a group of postmenopausal Turkish women: association with bone mineral density

OBJECTIVE

To evaluate the frequency of the estrogen receptor (ER) gene PvuII and XbaI polymorphisms and their associations with bone mineral density (BMD) in a group of postmenopausal Turkish women.

DESIGN

A total of 125 healthy postmenopausal women and 125 premenopausal healthy young women as controls were included in the study. The PvuII and XbaI polymorphisms in the ER gene were studied by the polymerase chain reaction-restriction fragment length polymorphism method. The BMD of the lumbar vertebrae and femoral neck were measured by dual-energy X-ray absorptiometry.

RESULTS

The frequencies of the ERα PVuII genotypes PP, Pp and pp were 20%, 54.4% and 25.6% in premenopausal and 24.8%, 44.8% and 30.4% in postmenopausal women, respectively. The frequencies of the ER XbaI genotypes XX, Xx, xx were 16.8%, 48.8% and 34.4% in premenopausal and 16.8%, 48% and 35.2% in postmenopausal women, respectively. There was no difference in the frequencies of ER gene polymorphisms between premenopausal and postmenopausal women. BMD measurements were not different between ER PvuII and XbaI genotypes in premenopausal and postmenopausal women.

CONCLUSIONS

ER gene PvuII and XbaI polymorphisms have no major influence on bone mineral density in our group of postmenopausal women.

Comparative analysis of clinical, biochemical and genetic aspects associated with bone mineral density in small for gestational age children

Clinical, biochemical and genetic analysis related to bone mineral density (BMD) were carried out in children born small for gestational age (SGA) that failed to achieve postnatal catch-up growth (CUG), SGA children that completed CUG and adequate for gestational age (AGA) children. Serum IGF-I, IGF-II, IGF binding protein-3 and acid-labile subunit were lower in the SGA-CUG children as compared with the other groups. Frequencies of polymorphic variants of vitamin D receptor, estrogen receptor and collagen genes were similar among groups. The genotype 194-192 of the IGF-I gene was higher in the SGA-CUG and 196-192 was higher in the SGA+CUG group. In the SGA-CUG group, the genotype SS of the COLIA1 gene was associated with lower BMD. Therefore, IGF system and COLIA1 polymorphism distinguish prepubertal SGA-CUG children from the SGA+CUG children of the same age. Furthermore, COLIA1 polymorphism could be useful to predict osteopenia in SGA-CUG children.

Vitamin D receptor genotypes are associated with bone mass in patients with Turner syndrome

BACKGROUND

Turner syndrome (TS) patients present low bone mineral density (BMD) and increased fracture risk, probably due to a genetic defect aggravated by hormonal deficiency.

AIM

To study the relationship between vitamin D receptor (VDR) gene polymorphisms and BMD and bone parameters in TS patients.

METHODS

DNA from 65 TS patients and 110 controls was amplified by PCR and digested with FokI, BsmI and ApaI restrictases. Lumbar and femoral BMD were determined by DEXA and serum intact parathyroid hormone, osteocalcin and beta-CrossLaps by electrochemiluminescence.

RESULTS

Genotype distribution within the ApaI site was different in both groups: genotype Aa was more abundant in TS (63.8% vs. 41.3%; p<0.01), whereas AA predominated in controls (33.9% vs. 15.5%; p<0.01). Patients carrying genotype bb (BsmI) or ff (FokI) had lower BMD than those with other genotypes (p<0.01 and p<0.05, respectively).

CONCLUSION

BsmI and FokI polymorphic sites of VDR could be genetic determinants of BMD in TS patients.

Molecular genetic studies of gene identification for osteoporosis: the 2009 update

Osteoporosis is a complex human disease that results in increased susceptibility to fragility fractures. It can be phenotypically characterized using several traits, including bone mineral density, bone size, bone strength, and bone turnover markers. The identification of gene variants that contribute to osteoporosis phenotypes, or responses to therapy, can eventually help individualize the prognosis, treatment, and prevention of fractures and their adverse outcomes. Our previously published reviews have comprehensively summarized the progress of molecular genetic studies of gene identification for osteoporosis and have covered the data available to the end of September 2007. This review represents our continuing efforts to summarize the important and representative findings published between October 2007 and November 2009. The topics covered include genetic association and linkage studies in humans, transgenic and knockout mouse models, as well as gene-expression microarray and proteomics studies. Major results are tabulated for comparison and ease of reference. Comments are made on the notable findings and representative studies for their potential influence and implications on our present understanding of the genetics of osteoporosis.

Molecular mechanisms triggered by low-calcium diets

Ca is not only essential for bone mineralisation, but also for regulation of extracellular and intracellular processes. When the Ca2+ intake is low, the efficiency of intestinal Ca2+ absorption and renal Ca2+ reabsorption is increased. This adaptive mechanism involves calcitriol enhancement via parathyroid hormone stimulation. Bone is also highly affected. Low Ca2+ intake is considered a risk factor for osteoporosis. Patients with renal lithiasis may be at higher risk of recurrence of stone formation when they have low Ca2+ intake. The role of dietary Ca2+ on the regulation of lipid metabolism and lipogenic genes in adipocytes might explain an inverse relationship between dairy intake and BMI. Dietary Ca2+ restriction produces impairment of the adipocyte apoptosis and dysregulation of glucocorticosteroid metabolism in the adipose tissue. An inverse relationship between hypertension and a low-Ca2+ diet has been described. Ca2+ facilitates weight loss and stimulates insulin sensitivity, which contributes to the decrease in the blood pressure. There is also evidence that dietary Ca2+ is associated with colorectal cancer. Dietary Ca2+ could alter the ratio of faecal bile acids, reducing the cytotoxicity of faecal water, or it could activate Ca2+-sensing receptors, triggering intracellular signalling pathways. Also it could bind luminal antigens, transporting them into mucosal mononuclear cells as a mechanism of immunosurveillance and promotion of tolerance. Data relative to nutritional Ca2+ and incidences of other human cancers are controversial. Health professionals should be aware of these nutritional complications and reinforce the dairy intakes to ensure the recommended Ca2+ requirements and prevent diseases.

The effect of telomere length, a marker of biological aging, on bone mineral density in elderly population

Telomere length (TL), as a reflection of aging and inflammatory processes, may be associated with bone mineral density (BMD). This study examines the association between TL and BMD cross-sectionally and the rate of bone loss over a 4-year period in 1,867 Chinese elderly community living subjects. After adjusting for confounding factors, no association was observed with BMD or bone loss. The decline in BMD with aging is not reflected by corresponding changes in telomere length.

INTRODUCTION

Bone mineral density (BMD) is influenced by the dynamics of aging, inflammatory, and bone remodeling processes. Telomere length (TL) is a reflection of the former two processes and may also be associated with bone loss.

METHODS

Hip BMD was measured in 1,867 Chinese elderly community living subjects and the relationship between leukocyte TL measured using quantitative real-time polymerase chain reaction, and bone loss after 4 years was examined.

RESULTS

Women had greater bone loss than men. In women, age of menopause, menarche, estrogen treatment/replacement therapy, and history of previous fracture were also among the significant covariates. However, in multivariate analyses, TL was not associated with BMD in either sex.

CONCLUSIONS

TL was not associated with either baseline BMD or bone loss over 4 years and accounted for less than 1.6% of the baseline BMD.