Association analysis of the polymorphisms of the VDR gene with bone mineral density and the occurrence of fractures

Evaluation of Association Studies and an Updated Meta-Analysis of VDR Polymorphisms in Osteoporotic Fracture Risk

Background: Several studies have examined the association between vitamin D receptor (VDR) polymorphisms and osteoporotic fracture risk; however, the results are not uniform. Furthermore, many new articles have been published, and therefore, an updated meta-analysis was performed to further explore these issues.

Objectives: The aim of the study was to investigate the association between VDR, BsmI, ApaI, TaqI, FokI, and Cdx2 polymorphisms and osteoporotic fracture risk.

Methods: The odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the association between VDR BsmI, ApaI, TaqI, FokI, and Cdx2 polymorphisms and the risk of osteoporotic fracture. We also used the false-positive reporting probability (FPRP) test and the Venice criteria to evaluate the credibility of the statistically significant associations.

Results: Overall, this study found that the VDR ApaI and BsmI polymorphisms significantly increased the risk of osteoporotic fracture in European countries and America, respectively. However, when sensitivity analysis was performed after excluding low-quality and Hardy–Weinberg disequilibrium (HWD) studies, it was found that only individuals with the double-mutated genotype have an increased risk of osteoporotic fracture in European countries. In addition, when the credibility of the positive results was assessed, it was found that the positive results were not credible.

Conclusion: This meta-analysis indicates that there may be no significant association among the polymorphisms of VDR BsmI, ApaI, TaqI, FokI, and Cdx2 and the risk of osteoporotic fracture. The increased risk of osteoporotic fracture is most likely due to false-positive results.

Does the VDR gene polymorphism influence the efficacy of denosumab therapy in postmenopausal osteoporosis?

INTRODUCTION

One of the challenges of personalized medicine is a departure from traditional pharmacology toward individualized, genotype-based therapies. Postmenopausal osteoporosis is a prevalent condition requiring intensive treatment, whose effects are measurable only after a long time, and the goal is bone fracture prevention. This study aimed to determine the influence of VDR gene variation on anti-osteoporotic one-year treatment with denosumab in 63 Polish women with postmenopausal osteoporosis.

MATERIALS AND METHODS

The correlation between bone mineral density (BMD) of the lumbar vertebral column (L1-L4) and femoral neck, and genotype distributions for the ApaI, BsmI, FokI, and TaqI variants of the VDR gene was analyzed. Bone fractures during denosumab therapy were also investigated.

RESULTS

In the case of the Bsml polymorphism, female patients with BB and Bb genotypes had statistically significantly higher values of BMD and T-score/Z-score indicators, which persisted after a year of denosumab treatment. Our results indicated that the Bsml polymorphism contributes to better bone status, and, consequently, to more efficient biological therapy. The study did not reveal significant differences between changes (delta) in BMD and genotypes for the analyzed VDR gene loci. In the entire study group, one bone fracture was observed in one patient throughout the yearlong period of denosumab therapy.

CONCLUSIONS

BB and Bb genotypes of the Bsml polymorphism of the VDR gene determine higher DXA parameter values both before and after one-year denosumab therapy in postmenopausal women with osteoporosis.

Vitamin D Status, Bone Mineral Density, and VDR Gene Polymorphism in a Cohort of Belarusian Postmenopausal Women

Vitamin D plays an important role in bone metabolism and is important for the prevention of multifactorial pathologies, including osteoporosis (OP). The biological action of vitamin is realized through its receptor, which is coded by the VDR gene. VDR gene polymorphism can influence individual predisposition to OP and response to vitamin D supplementation. The aim of this work was to reveal the effects of VDR gene ApaI rs7975232, BsmI rs1544410, TaqI rs731236, FokI rs2228570, and Cdx2 rs11568820 variants on bone mineral density (BMD), 25-hydroxyvitamin D level, and OP risk in Belarusian women. Methods. The case group included 355 women with postmenopausal OP, and the control group comprised 247 women who met the inclusion criteria. TaqMan genotyping assay was used to determine VDR gene variants. Results. Rs7975232 A/A, rs1544410 T/T, and rs731236 G/G single variants and their A-T-G haplotype showed a significant association with increased OP risk (for A-T-G, OR = 1.8, p = 0.0001) and decreased BMD (A-T-G, −0.09 g/cm², p = 0.0001). The rs11568820 A-allele showed a protective effect on BMD (+0.22 g/cm², p = 0.027). A significant dose effect with 25(OH)D was found for rs1544410, rs731236, and rs11568820 genotypes. Rs731236 A/A was associated with the 25(OH)D deficiency state. Conclusion. Our novel data on the relationship between VDR gene variants and BMD, 25(OH)D level, and OP risk highlights the importance of genetic markers for personalized medicine strategy.

Relationship of vitamin D receptor gene polymorphisms with susceptibility, surgical outcome and prognosis of hallux valgus in a Chinese Han population

BACKGROUND

This study aimed to identify the relationship between the vitamin D receptor (VDR) BsmI gene polymorphism and risk factors, surgical outcome and prognosis of hallux valgus (HV).

METHODS

A case-control study was performed on a cohort of 236 HV patients and 236 controls in a Chinese Han population. Detection of the VDR BsmI/G2A polymorphism was performed using restriction fragment length polymorphism-polymerase chain reaction.

RESULTS

We detected a statistically significant difference in the allele distribution of the BsmI polymorphism between cases and controls (p<0.01). Significant loss of hallux valgus angle (HVA) and intermetatarsal angle (IMA) correction was only noted in patients with the bb genotype during the 2-year follow-up period (p<0.01). The average American Orthopaedic Foot and Ankle Society (AOFAS) scores at the 2-year follow-up were decreased in both groups when compared with those at the 6 month follow-up, and 1.45 points more decrease in patients with the bb genotype was observed as compared to those with the BB and Bb genotypes (p<0.0001). The average visual analogue scales (VAS) also had the tendency with more pains in the bb genotype group (p<0.0001). Furthermore, larger numbers of transfer metatarsalgia were found in patients with the bb genotype upon 2-year follow-up (p=0.049).

CONCLUSIONS

We report the first candidate gene polymorphism associated with susceptibility, surgical outcome and prognosis of HV in a Chinese Han population. Moreover, development of genetically-based method to predict the surgical outcome accurately and individualized therapy for HV are warranted.

The interactions of physical activity, exercise and genetics and their associations with bone mineral density: implications for injury risk in elite athletes

Low bone mineral density (BMD) is established as a primary predictor of osteoporotic risk and can also have substantial implications for athlete health and injury risk in the elite sporting environment. BMD is a highly multi-factorial phenotype influenced by diet, hormonal characteristics and physical activity. The interrelationships between such factors, and a strong genetic component, suggested to be around 50-85% at various anatomical sites, determine skeletal health throughout life. Genome-wide association studies and case-control designs have revealed many loci associated with variation in BMD. However, a number of the candidate genes identified at these loci have no known associated biological function or have yet to be replicated in subsequent investigations. Furthermore, few investigations have considered gene-environment interactions-in particular, whether specific genes may be sensitive to mechanical loading from physical activity and the outcome of such an interaction for BMD and potential injury risk. Therefore, this review considers the importance of physical activity on BMD, genetic associations with BMD and how subsequent investigation requires consideration of the interaction between these determinants. Future research using well-defined independent cohorts such as elite athletes, who experience much greater mechanical stress than most, to study such phenotypes, can provide a greater understanding of these factors as well as the biological underpinnings of such a physiologically "extreme" population. Subsequently, modification of training, exercise or rehabilitation programmes based on genetic characteristics could have substantial implications in both the sporting and public health domains once the fundamental research has been conducted successfully.

VDR, RANKL and OPG polymorphisms as possible predisposing cofactors of postmenopausal osteoporosis: explorative study in Italian population

Postmenopausal osteoporosis (PO) has a strong genetic component. Presently, the published evidence on the association between the main single-nucleotide polymorphisms (SNPs) of the receptor activator of nuclear factor-kb ligand (RANKL), osteoprotegerin (OPG) and vitamin D receptor (VDR) and bone mass density (BMD) are scarce, mostly considering Italian population. This study sought to determine whether OPG (rs2073618), RANKL (rs9525641) and the VDR (rs2228570) SNPs were associated with BMD in a sample of 139 North-Italian postmenopausal women. The allelic distribution of rs9525641 in women with PO or osteopenia (OP + OPE group) differed from controls (p < 0.05), suggesting that this allele might confer a greater susceptibility to bone resorption. Concerning rs2228570, CC genotype was associated with OP + OPE women, with a worst total hip BMD. Notably, the combined genotype RANK (CT)-VDR (TT) was significantly associated to spine BMD (p < 0.05). In conclusion, this pilot study showed that rs9525641 and rs2228570 polymorphisms might contribute, separately or in combination, in determining BMD phenotype in selected postmenopausal populations.

Association between Vitamin D Receptor Polymorphism and Serum Vitamin D Levels in Children with Low-Energy Fractures

OBJECTIVE

Fractures of bones, especially forearm fractures, are very common in children and their number is increasing. This study was designed to determine the impact of vitamin D serum levels and vitamin D receptor (VDR) polymorphisms on the occurrence of low-energy fractures in children.

METHODS

The study group consisted of 100 children with clinically relevant bone fractures and a control group consisted of 127 children without fractures. Total vitamin D [25(OH)D3 plus 25(OH)D2] serum concentrations were evaluated in every patient. Genotypes for 4 restriction fragment length polymorphisms of the vitamin D receptor gene (FokI, ApaI, TaqI, and BsmI) were determined by standard polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) techniques.

RESULTS

Differences in concentrations of vitamin D were observed between the group with bone fractures (median = 12 ng/ml) and the control group (median = 16 ng/ml; p = 0.000044). Higher levels of vitamin D reduced the risk of fracture by 1.06 times (p = 0.0005). No impact of particular VDR polymorphism on the occurrence of low-energy fractures in children was detected. However, there were significant differences in the prevalence of FokI polymorphism genotypes between the fracture and control groups (p = 0.05). Furthermore, the recessive "aa" genotype of ApaI polymorphism and the dominant "TT" genotype of TaqI polymorphism were associated with higher levels of vitamin D (p = 0.005 and p = 0.036, respectively).

CONCLUSIONS

Vitamin D deficiency is an independent risk factor for fractures in children. ApaI polymorphism recessive "aa" and TaqI polymorphism dominant "TT" genotypes are associated with higher levels of vitamin D in serum.

Modulation of keratin in adhesion, proliferation, adipogenic, and osteogenic differentiation of porcine adipose-derived stem cells

Recently, keratin attracts tremendous interest because of its intrinsic ability to interact with different cells. It has the potential to serve as a controllable extracellular matrix protein that can be used to demonstrate cell mechanism and cell-matrix interaction. However, there have been relatively few studies on the effects of keratin on stem cells. In the present work, we study the effects of human keratin on porcine adipose-derived stem cells (pASCs) and a series of selective cell lines: 3T3 fibroblasts, Madin-Darby canine kidney (MDCK) cells, and MG63 osteoblasts. Relative to un-treated culture plate, our results showed that keratin coating substrates promote cell adhesion and proliferation to above cell lines. Keratin also improved pASCs adhesion, proliferation, and enhanced cell viability. Evaluation of genetic markers showed that adipogenic and osteogenic differentiations of pASCs can be successfully induced, thus demonstrating that keratin did not influence the stemness of pASCs. Furthermore, keratin improved adipogenic differentiations of pASCs in terms of up-regulations in lipoprotein lipase, peroxisome proliferator-activated receptor gamma, and CCAAT-enhancer-binding protein alpha. The osteogenic markers type I collagen, runt-related transcription factor 2, and vitamin D receptor were also upregulated when pASCs cultured on keratin substrates. Therefore, keratin can serve as a biological derived material for surface modification and scaffold fabrication for biomedical purpose. The combination of keratin with stem cells may be a potential candidate for tissue repair in the field of regenerative medicine. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 180-192, 2017.

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.

Analysis of FokI polymorphism of vitamin D receptor gene in intervertebral disc degeneration

AIM

We have hypothesized a possible relationship between disc degeneration (DD) and VDR FokI/T2C polymorphism.

METHODS

A case-control study was performed comprising 121 Brazilian patients with confirmed DD by nuclear magnetic resonance and a control group consisting of 131 healthy patients without a history of disc cysts of the lumbar spine. Detection of VDR FokI/T2C polymorphism was performed using restriction fragment length polymorphism-polymerase chain reaction. The chi-square test was used to compare allele and genotype frequencies between groups, and a p-value of <0.05 was considered statistically significant.

RESULTS

The results disclosed statistical difference between allele distribution among cases and controls (p=0.025, odds ratio=1.58, confidence interval=1.07-2.32) considering VDR FokI/T2C polymorphism.

CONCLUSION

The results showed a positive association between VDR FokI/T2C polymorphism and DD in Brazilian patients tested.

Vitamin D receptor gene polymorphisms, bone mineral density and fractures in postmenopausal women with osteoporosis

The goal of the study was to investigate the possibility of an association between polymorphisms and single alleles of BsmI, ApaI, TaqI of the vitamin D receptor (VDR) gene with bone mineral density (BMD) and prevalence of vertebral/non-vertebral fractures in a group of postmenopausal Polish women with osteoporosis. The study group comprised of 501 postmenopausal females with osteoporosis (mean age 66.4 ± 8.9), who were diagnosed on the basis of either the WHO criteria or self-reported history of low-energy fractures. The three polymorphisms were determined by PCR (polymerase chain reaction) and RFLP (restriction fragment length polymorphism). BMD at the lumbar spine and femoral neck was assessed by dual energy X-ray absorptiometry (DXA). 285 fractures were reported in the whole group (168 vertebral and 117 non-vertebral). Incidence of non-vertebral fractures was significantly higher in the carriers of single alleles a of ApaI, b of BsmI and T of TaqI VDR gene polymorphisms (p = 0.021, 0.032, 0.020, respectively). No significant associations between allelic variants of the studied polymorphisms and BMD or fracture incidence were found. (1).The presence of single alleles a,b and T of ApaI, BsmI, TaqI VDR gene polymorphisms respectively, might serve as an indicator of non-vertebral fractures. (2). Lack of association between the VDR gene polymorphisms and BMD suggests that VDR contributes to low-energy fractures also through other ways.

Association of vitamin D receptor gene start codon (Fok1) polymorphism with high myopia

Background:

High myopia caused primarily due to abnormal emmetropization and excessive axial ocular elongation is associated with sight-threatening ocular pathology. Muscular dysfunction of ocular ciliary muscles due to altered intracellular calcium levels can result in defective mechanotransduction of the eye and retinal defocus. The vitamin D3 receptor (VDR; a intracellular hormone receptor) is known to mediate calcium homeostasis, influencing the development of myopia.

Materials and Methods:

In the present study, a total of 206 high myopia, 98 low myopia and 250 control samples were analyzed for VDR gene Fok1 (exon 2 start codon) polymorphism using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique.

Results:

High myopia patients revealed decrease in the frequency of ff homozygotes (8.3%) as compared to control group (14.0%), with a corresponding increase in frequency of FF homozygotes (68.9% in high myopia vs. 62.8% in controls). The frequency of f allele carriers (Ff and ff) was increased in females of high myopia (35.6%) and low myopia cases (45.4%). Elevated frequency of f allele was found only in early age at onset cases of high myopia (0.227) and later age at onset (10–20 years) cases of low myopia (0.273) as well as in low myopia cases with parental consanguinity (0.458) (P 0.035; χ² = 6.692*).

Conclusion:

The results suggest that VDR gene might not be playing a direct role in the development of myopia, but might contribute indirectly to the risk conferred by mechanical stress factors or growth/development related factors through its role in calcium homeostasis and regulation of ciliary muscle function.

A susceptible haplotype within APOE gene influences BMD and intensifies the osteoporosis risk in postmenopausal women of Northwest India

BACKGROUND

The association of apolipoprotein E (APOE) genotypes with bone mineral density (BMD) and risk of osteoporosis have remained unclear. The influence of APOE gene polymorphisms on BMD as genetic mediators of osteoporosis risk needs to be explored in Indian postmenopausal females where this disease is rising rampantly.

METHODS AND RESULTS

The present study investigated the role and relevance of four pertinent APOE single nucleotide polymorphisms: 5'UTR G/C (rs440446), Int2 G/A (rs769450), Exon4 T/C (rs429358), Exon4C/T (rs7412) in DEXA verified 133 osteoporotic, 57 osteopenic and 83 normal postmenopausal females of India, who were not taking hormone replacement therapy. Minor allele frequencies of rs440446 and rs429358 were higher in osteoporotic females (0.31, 0.18) than osteopenic (0.29, 0.15) and females having normal bone mass (0.16, 0.07). Disease association analysis revealed a susceptibility haplotype CGTC (in order of rs440446, rs769450, rs429358, rs7412) and the carriers of this haplotype has higher risk of osteopenia (OR 3.53, 95% CI 1.21-11.0, P=0.017) and osteoporosis (OR 3.61, 95% CI 1.53-9.48, P=0.002) after adjusting the confounding effect of age, BMI and years since menopause. Females who possess either one copy or two copies of the haplotype have lesser BMD values of lumbar spine (0.88 and 0.85 g/cm(2)) and femoral neck (0.84 and 0.82 g/cm(2)) than those females who possess zero copy (0.9 and 0.87 g/cm(2), respectively).

CONCLUSIONS

The present study exposed a susceptibility haplotype CGTC, within APOE gene, which was found to be associated with BMD and risk of osteopenia and osteoporosis in postmenopausal females of India.

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.

Chronic liver disease and osteoporosis

Hepatic osteodystrophy, manifesting mainly as osteoporosis, can occur in patients with chronic liver disease (CLD) or after liver transplantation and lead to vertebral compression fracture, radial or femoral fracture. Currently, the pathogenesis of hepatic osteodystrophy is still not completely clear. The reported incidence of osteoporosis in CLD patients ranged from 12% to 55%. For CLD patients, attention should be paid to monitor osteoporosis by measuring bone mineral density on the basis of controlling liver disease to choose safe and effective medication to improve their quality of life.

BsmI, TaqI, ApaI and FokI polymorphisms in the vitamin D receptor (VDR) gene and risk of fracture in Caucasians: a meta-analysis

CONTEXT

Vitamin D receptor (VDR) gene polymorphisms have been strongly associated with bone mineral density in some studies. However, in a recent meta-analysis, no relationship of the VDR BsmI or TaqI polymorphism and fracture risk was found in the meta-analysis of published data.

OBJECTIVE AND DESIGN

Our meta-analysis studied whether a relationship exists between BsmI, TaqI, ApaI and FokI polymorphisms in the VDR gene and risk of fracture.

DATA SOURCES

Relevant studies were identified from the following electronic databases: MEDLINE, EMBASE and Current Contents before January 2010.

DATA SYNTHESIS

This meta-analysis included 17 studies with a total of 21 eligible comparisons, which included 2112 fracture cases and 4521 controls. All of these studies reported on Caucasians. The combined results based on all studies showed that fracture cases had a significantly lower frequency of bb genotype of BsmI [odds ratio (OR) = 0.87, 95% confidence interval (CI)=0.76, 0.98]. When stratifying by fracture type, we found that (1) hip fracture cases had a significantly lower frequency of bb genotype of BsmI (OR=0.82, 95% CI=0.70, 0.97); (2) hip fracture cases had a significantly lower frequency of Tt genotype of TaqI (OR=0.65, 95% CI=0.43, 0.97); (3) hip fracture cases had a significantly higher frequency of tt genotype of TaqI (OR=1.74, 95% CI=1.05, 2.91); (4) vertebral fracture cases had a significantly higher frequency of Aa genotype of ApaI (OR=1.63, 95% CI=1.03, 2.59). No significant difference was found in any genotype of FokI.

CONCLUSION

Our meta-analysis suggests that there is a modest but statistically significant association between the BsmI bb genotypes and fracture.

Quantitative trait loci, genes, and polymorphisms that regulate bone mineral density in mouse

This is an in silico analysis of data available from genome-wide scans. Through analysis of QTL, genes and polymorphisms that regulate BMD, we identified 82 BMD QTL, 191 BMD-associated (BMDA) genes, and 83 genes containing known BMD-associated polymorphisms (BMDAP). The catalogue of all BMDA/BMDAP genes and relevant literatures are provided. In total, there are substantially more BMDA/BMDAP genes in regions of the genome where QTL have been identified than in non-QTL regions. Among 191 BMDA genes and 83 BMDAP genes, 133 and 58 are localized in QTL regions, respectively. The difference was still noticeable for the chromosome distribution of these genes between QTL and non-QTL regions. These results have allowed us to generate an integrative profile of QTL, genes, polymorphisms that determine BMD. These data could facilitate more rapid and comprehensive identification of causal genes underlying the determination of BMD in mouse and provide new insights into how BMD is regulated in humans.

Vitamin D receptor polymorphisms and falls among older adults living in the community: results from the ilSIRENTE study

Vitamin D receptor (VDR) genotypes were associated with cognitive status, depressive symptoms, strength, and sarcopenia, but, thus far, no study has assessed their relationship with falls. The objective of this study is to evaluate whether, in a population of older adults living in the community, VDR FokI and BsmI genotypes are associated with falls. To this aim, we used data from the baseline evaluation of the ilSIRENTE study, which enrolled older adults >or= 80 yr of age living in the community in Italy. Falls occurring within 90 days of assessment were assessed by study personnel. The mean age of 259 study participants was 85.0 +/- 4.5 (SD) yr; 172 (66.4%) were women. Overall, 33 (12.7%) participants reported one or more falls. The rate of falls was 19.5% in participants with the BB genotype, 11.1% in those with Bb genotype, and 5.9% in those with bb genotype (p for linear trend = 0.02). After adjusting for potential confounders, compared with participants with the BB genotype, those with the bb genotype had a significantly lower OR for falls 0.14 (95% CI, 0.03-0.66). Rate of falls did not differ significantly across FokI genotypes (FF: 14.4%, Ff: 11.9%, ff: 9.1%; p = 0.43). In conclusion, the VDR bb genotype of the BsmI gene is associated with a reduced rate of falls compared with the BB genotype, whereas no effect on falls was shown for FokI polymorphism. Further studies conducted in larger population are needed to confirm the association of BsmI genotype and falls and to understand reasons for these findings.

The vitamin D receptor Fok1 polymorphism and bone mineral density in Chinese children

BACKGROUND

To evaluate the relationship between vitamin D receptor (VDR) gene polymorphism and bone mineral density (BMD) in 213 healthy children aged 6-10 year in China.

METHODS

A questionnaire survey of dietary pattern, outdoor activity was conducted among 213 children (boys 126, girls 86) randomly selected in Xishui county of Hubei province. The BMD was determined by dual energy X-ray absorptiometry at the distal forearm, calcium, phosphorus, and alkaline phosphatase in serum were immediately analyzed. The FokI polymorphism was detected by using PCR-RFLP.

RESULTS

BMD was significantly higher in boys than in girls in 8/9 year group. (2) the frequencies of FF, Ff, and ff genotype were 25.8%, 62.0% and 12.2%, respectively; no difference was found between boys and girls. (3) BMD of children carrying FF genotype was higher (0.256+/-0.03) than those of carrying Ff genotype (0.241+/-0.03), P<0.01; the Ff genotype was associated with lowest forearm BMD in both boys and girls. Outdoor activity also positively affected peak bone mass.

CONCLUSION

The Fok1 polymorphism of the VDR receptor seems to directly affect bone mineral mass in Chinese children.

Molecular genetic studies of gene identification for osteoporosis

This review comprehensively summarizes the most important and representative molecular genetics studies of gene identification for osteoporosis published up to the end of September 2007. It is intended to constitute a sequential update of our previously published reviews covering the available data up to the end of 2004. Evidence from candidate gene-association studies, genome-wide linkage and association studies, as well as functional genomic studies (including gene-expression microarray and proteomics) on osteogenesis and osteoporosis, are reviewed separately. Studies of transgenic and knockout mice models relevant to osteoporosis are summarized. The major results of all studies are tabulated for comparison and ease of reference. Comments are made on the most notable findings and representative studies for their potential influence and implications on our present understanding of genetics of osteoporosis. The format adopted by this review should be ideal for accommodating future new advances and studies.