Relation of alleles of the collagen type Ialpha1 gene to bone density and the risk of osteoporotic fractures in postmenopausal women

Association between the Sp1-binding-site polymorphism in the collagen type I alpha 1 (COLIA1) gene and bone phenotypes: the Dubbo Osteoporosis Epidemiology Study

INTRODUCTION

Polymorphisms within the collagen 1 alpha 1 gene (COLIA1) have been shown to be associated with bone mineral density (BMD). This study aimed to test the hypothesis that COLIA1 polymorphisms are associated with bone loss and fragility fractures.

MATERIALS AND METHODS

The study involved 809 postmenopausal women aged 60 years and above in the Dubbo Osteoporosis Epidemiology Study who had COLIA1 genotypes and at least two BMD measurements over a 30-year period. BMD at the lumbar spine (LSBMD) and femoral neck (FNBMD) was measured biennially by dual-energy X-ray absorptiometry (GE-Lunar Prodigy). Fragility fracture has been ascertained by X-ray reports between 1990 and 2020. The G-> T polymorphism at the Sp1-binding site in the COLIA1 gene (rs1800012) was determined by the PCR-based method, and coded as GG, GT, and TT.

RESULTS

Women homozygous for the minor allele (TT) tended to have greater bone loss (-0.72%/year) than those with GT (-0.58%/year) or GG (-0.56%/year) though the difference did not achieve statistical significance (P = 0.84). Women of the TT genotype were associated with a two-fold greater risk of any fracture (adjusted hazard ratio: 2.21; 95%CI 1.42-3.46) and almost fourfold greater risk of hip fracture (3.78; 1.83-7.82) than those with either GG or GT genotype.

CONCLUSIONS

Polymorphisms at the Sp1 site in the COLIA1 gene are associated with fracture risk, independent of bone loss.

The structural basis for the collagen processing by human P3H1/CRTAP/PPIB ternary complex

Collagen posttranslational processing is crucial for its proper assembly and function. Disruption of collagen processing leads to tissue development and structure disorders like osteogenesis imperfecta (OI). OI-related collagen processing machinery includes prolyl 3-hydroxylase 1 (P3H1), peptidyl-prolyl cis-trans isomerase B (PPIB), and cartilage-associated protein (CRTAP), with their structural organization and mechanism unclear. We determine cryo-EM structures of the P3H1/CRTAP/PPIB complex. The active sites of P3H1 and PPIB form a face-to-face bifunctional reaction center, indicating a coupled modification mechanism. The structure of the P3H1/CRTAP/PPIB/collagen peptide complex reveals multiple binding sites, suggesting a substrate interacting zone. Unexpectedly, a dual-ternary complex is observed, and the balance between ternary and dual-ternary states can be altered by mutations in the P3H1/PPIB active site and the addition of PPIB inhibitors. These findings provide insights into the structural basis of collagen processing by P3H1/CRTAP/PPIB and the molecular pathology of collagen-related disorders.

A Case-control Study of Major Genetic Predisposition Risk Alleles in Developing DDD in the Northeast US Population: Effects of Gene-gene Interactions

STUDY DESIGN

A case-control study of risk alleles for degenerative disc disease (DDD) using magnetic resonance (MR) imaging for phenotyping.

OBJECTIVE

We aim to provide the first statistically adequately powered study of the relationship between the presence of common risk alleles and occurrence of DDD in Eastern US population.

SUMMARY OF BACKGROUND DATA

Many genetic predisposing factors have been identified in elevating the risk of DDD, including common variants in VDR, COL1A1, AGC1, COL9A2/3 genes.

METHODS

We utilized the Mass General Brigham (MGB) Biobank in which subjects' Medical Record is linked with genotyped data from single-nucleotide polymorphism (SNP) arrays. Subjects with lumbosacral spine MR imaging studies were used to construct the Cases cohort; the Biobank's Controls cohort was used as the Control cohort. Odds ratios (OR) and False-discovery-rate (FDR) q values from multiple-hypotheses-testing corrections were used to assess the likelihood of DDD given occurrence of the listed DDD risk alleles.

RESULTS

Four-hundred-fourteen subjects (mean age = 64, range = 27 to 94) were Cases and 925 Controls (mean age = 46, range = 21-61). A systematic search has identified 25 SNPs in 18 genes in the SNP arrays. At univariate level, rs1544410 in VDR was significantly associated with DDD for male subjects (odds ratio [OR] = 0.594, P = 0.011). After adjustment for all significant variants and demographics, three predictor variables had a significant association with the outcome, age (OR = 1.130, q < 0.0001), rs143383 (OR = 1.951, q = 0.056), and rs3737821 (OR = 2.701, q = 0.069). A novel variant-to-variant correlation rs143383:rs763110 had a significant adjusted OR = 7.933, q = 0.070).

CONCLUSION

In this large-scale study of common variants' correlation with the presence of DDD in the Northeast United States, we have found a novel and significant variant-to-variant interaction to be associated with the risk of developing DDD, corroborating and necessitating the inclusion of gene-gene interactions in predictive risk model development for DDD.Level of Evidence: 4.

Genome-wide association study implicates novel loci and reveals candidate effector genes for longitudinal pediatric bone accrual

BACKGROUND

Bone accrual impacts lifelong skeletal health, but genetic discovery has been primarily limited to cross-sectional study designs and hampered by uncertainty about target effector genes. Here, we capture this dynamic phenotype by modeling longitudinal bone accrual across 11,000 bone scans in a cohort of healthy children and adolescents, followed by genome-wide association studies (GWAS) and variant-to-gene mapping with functional follow-up.

RESULTS

We identify 40 loci, 35 not previously reported, with various degrees of supportive evidence, half residing in topological associated domains harboring known bone genes. Of several loci potentially associated with later-life fracture risk, a candidate SNP lookup provides the most compelling evidence for rs11195210 (SMC3). Variant-to-gene mapping combining ATAC-seq to assay open chromatin with high-resolution promoter-focused Capture C identifies contacts between GWAS loci and nearby gene promoters. siRNA knockdown of gene expression supports the putative effector gene at three specific loci in two osteoblast cell models. Finally, using CRISPR-Cas9 genome editing, we confirm that the immediate genomic region harboring the putative causal SNP influences PRPF38A expression, a location which is predicted to coincide with a set of binding sites for relevant transcription factors.

CONCLUSIONS

Using a new longitudinal approach, we expand the number of genetic loci putatively associated with pediatric bone gain. Functional follow-up in appropriate cell models finds novel candidate genes impacting bone accrual. Our data also raise the possibility that the cell fate decision between osteogenic and adipogenic lineages is important in normal bone accrual.

Composition and characteristics of trabecular bone in osteoporosis and osteoarthritis

BACKGROUND

Bone strength depends on multiple factors such as bone density, architecture and composition turnover. However, the role these factors play in osteoporotic fractures is not well understood.

PURPOSE

The aim of this study was to analyze trabecular bone architecture, and its crystal and organic composition in humans, by comparing samples taken from patients who had a hip fracture (HF) and individuals with hip osteoarthritis (HOA).

METHODS

The study included 31 HF patients and 42 cases of HOA who underwent joint replacement surgery between 1/1/2013 and 31/12/2013. Trabecular bone samples were collected from the femoral heads and analyzed using a dual-energy X-ray absorptiometry, micro-CT, and solid-state high-resolution magic-angle-spinning nuclear magnetic resonance (MAS-NMR) spectroscopy.

RESULTS

No differences in proton or phosphorus concentration were found between the two groups using ¹H single pulse, ³¹P single pulse, ³¹P single pulse with proton decoupling NMR spectroscopy, in hydroxyapatite (HA) c-axis or a-axis crystal length. Bone volume fraction (BV/TV), trabecular number (Tb.N), and bone mineral density (BMD) were higher in the HO group than in the HF group [28.6% ± 10.5 vs 20.3% ± 6.6 (p = 0.026); 2.58 mm^-1 ± 1.57 vs 1.5 mm^-1 ± 0.79 (p = 0.005); and 0.39 g/cm² ± 0.10 vs. 0.28 g/cm² ± 0.05 (p = 0.002), respectively]. The trabecular separation (Tp.Sp) was lower in the HO group 0.42 mm ± 0.23 compared with the HF group 0.58 mm ± 0.27 (p = 0.036). In the HO group, BMD was correlated with BV/TV (r = 0.704, p < 0.001), BMC (r = 0.853, p < 0.001), Tb.N (r = 0.653, p < 0.001), Tb.Sp (-0.561, p < 0.001) and ¹H concentration (-0.580, p < 0.001) in the HO group. BMD was not correlated with BV/TV, Tb.Sp, Tb.Th, Tb.N, Tb.PF, ¹H concentration or HA crystal size in the HF group.

CONCLUSIONS

Patients with HO who did not sustain previous hip fractures had a higher femoral head BMD, BV/TV, and Tb.N than HF patients. In HO patients, BMD was positively correlated with the BV/TV and Tb.N and negatively correlated with the femoral head organic content and trabecular separation. Interestingly, these correlations were not found in HF patients with relatively lower bone densities. Therefore, osteoporotic patients with similar low bone densities could have significant microstructural differences. No differences were found between the two groups at a HA crystal level.

Association of the Sp1 binding site and -1997 promoter variations in COL1A1 with osteoporosis risk: The application of meta-analysis and bioinformatics approaches offers a new perspective for future research

As a complex disease, osteoporosis is influenced by several genetic markers. Many studies have examined the link between the Sp1 binding site +1245 G > T (rs1800012) and -1997 G > T (rs1107946) variations in the COL1A1 gene with osteoporosis risk. However, the findings of these studies have been contradictory; therefore, we performed a meta-analysis to aggregate additional information and obtain increased statistical power to more efficiently estimate this correlation. A meta-analysis was conducted with studies published between 1991-2020 that were identified by a systematic electronic search of the Scopus and Clarivate Analytics databases. Studies with bone mineral density (BMD) data and complete genotypes of the single-nucleotide variations (SNVs) for the overall and postmenopausal female population were included in this meta-analysis and analyzed using the R metaphor package. A relationship between rs1800012 and significantly decreased BMD values at the lumbar spine and femoral neck was found in individuals carrying the "ss" versus the "SS" genotype in the overall population according to a random effects model (p < 0.0001). Similar results were also found in the postmenopausal female population (p = 0.003 and 0.0002, respectively). Such findings might be an indication of increased osteoporosis risk in both studied groups in individuals with the "ss" genotype. Although no association was identified between the -1997 G > T and low BMD in the overall population, those individuals with the "GT" genotype showed a higher level of BMD than those with "GG" in the subgroup analysis (p = 0.007). To determine which transcription factor (TF) might bind to the -1997 G > T in COL1A1, 45 TFs were identified based on bioinformatics predictions. According to the GSE35958 microarray dataset, 16 of 45 TFs showed differential expression profiles in osteoporotic human mesenchymal stem cells relative to normal samples from elderly donors. By identifying candidate TFs for the -1997 G > T site, our study offers a new perspective for future research.

Sp1 Binding Site Polymorphism at COL1A1 Gene and Its Relation to Bone Mineral Density for Osteoporosis Risk Factor Among the Sikkimese Men and Women of Northeast India

Single nucleotide polymorphism in the first intron of Collagen type I alpha 1 (COL1A1) gene which is the binding site of specificity protein 1 (Sp1) transcription factor associated with low bone mineral density and osteoporosis. To evaluate such genetic factors among the Sikkimese population, a total of 150 cases (75 men and 75 women) with primary osteopenia and osteoporosis and 150 healthy controls (75 men and 75 women) of age range between 35 and 65 years were enrolled in this study. The COL1A1 genotypes [SS, Ss and ss] were assessed by restriction enzyme [MscI] digestion of DNA after amplification by polymerase chain reaction. There, only 2.7% women and 1.3% men cases had restriction site with heterozygous genotype (Ss) and no homozygous genotype (ss) were detected. There was no statistically significant association between low bone mass and genotypes on analysis (χ² = 1.014, P = 0.314; RR = 1.510) that, the Sp1 binding site polymorphism at the COLIA1 gene is very rare and has no contribution in the development low bone mineral density.

Postmenopausal osteoporotic fracture-associated COLIA1 variant impacts bone accretion in girls

Over the past two decades, a low frequency variant (rs1800012) within the first intron of the type I collagen alpha 1 (COLIA1) gene has been implicated in lower areal BMD (aBMD) and increased risk of osteoporotic fracture. This association is particularly strong in postmenopausal women, in whom net bone loss arises in the context of high bone turnover. High bone turnover also accompanies childhood linear growth; however, the role of rs1800012 in this stage of net bone accretion is less well understood. Thus, we assessed the association between rs1800012 and aBMD and bone mineral content (BMC) Z-scores for the 1/3 distal radius, lumbar spine, total hip, and femoral neck total body less head in the Bone Mineral Density in Childhood Study, a mixed-longitudinal cohort of children and adolescents (total n = 804 girls and 771 boys; n = 19 girls and 22 boys with the TT genotype). Mixed effects modeling, stratified by sex, was used to test for associations between rs1800012 and aBMD or BMC Z-scores and for pubertal stage interactions. Separately, SITAR growth modeling of aBMD and BMC in subjects with longitudinal data reduced the complex longitudinal bone accrual curves into three parameters representing a-size, b-timing, and c-velocity. We tested for differences in these three parameters by rs1800012 genotype using t-tests. Girls with the TT genotype had significantly lower aBMD and BMC Z-scores prior to puberty completion (e.g. spine aBMD-Z P-interaction = 1.0 × 10-6), but this association was attenuated post-puberty. SITAR models revealed that TT girls began pubertal bone accrual later (b-timing; e.g. total hip BMC, P = 0.03). BMC and aBMD Z-scores also increased across puberty in TT homozygous boys. Our data, along with previous findings in post-menopausal women, suggest that rs1800012 principally affects female bone density during periods of high turnover. Insights into the genetics of bone gain and loss may be masked during the relatively quiescent state in mid-adulthood, and discovery efforts should focus on early and late life.

Associations between polymorphisms of the PDLIM4 gene and susceptibility to osteoporotic fracture in an elderly population of Han Chinese

The aim of the present study was to investigate the associations between single nucleotide polymorphisms (SNPs) in the PDZ and LIM domain protein 4 (PDLIM4) gene and susceptibility to osteoporotic fracture in an elderly Han Chinese population. Seven SNPs of PDLIM4, including rs77584624, rs78418541, rs270611, rs3900945, rs77486529, rs71583465, and rs366512, were examined in 540 elderly Chinese patients with osteoporotic fractures (case group) and 540 healthy Chinese subjects (control group) using Sanger sequencing. A-allele carriers of rs270611 in PDLIM4 had a significantly high risk of osteoporotic fracture (adjusted odds ratio [OR] = 1.34; 95% confidence interval [CI]: 1.24–1.46; P<0.001). Similarly, individuals carrying the C-allele at PDLIM4 rs3900945 were predisposed to osteoporotic fracture (adjusted OR = 1.45; 95% CI: 1.05–1.25; P<0.001). In contrast, the T-allele at rs366512 appeared to be a protective genetic factor against osteoporotic fracture (adjusted OR = 0.84; 95% CI: 0.74–0.95; P<0.01). Consistently, the serum levels of N-terminal propeptide of type I procollagen (PINP) and C-telopeptide fragments of Collagen type I α1 chains (β-CTx) were higher in A-allele carriers of rs270611 and C-allele carriers of rs3900945, while T-allele carriers of rs366512 had lower PINP and β-CTx levels. Corresponding well with published findings, the A-allele of rs270611 and C-allele of rs3900945 were associated with reduced bone marrow density (BMD) at the fracture site, while T-allele carriers of rs366512 were shown to have normal BMD. Our study provides supportive evidence for the contribution of PDLIM4 gene polymorphisms to the susceptibility to osteoporotic fracture and suggests that rs270611 and rs3900945 are genetic risk factors, while rs366512 might be a genetic protective factor against osteoporotic fracture in elderly Han individuals.

Causes of low peak bone mass in women

Peak bone mass is the maximum bone mass that accrues during growth and development. Consolidation of peak bone mass normally occurs during early adulthood. Low peak bone mass results from failure to achieve peak bone mass genetic potential, primarily due to bone loss caused by a variety of conditions or processes occurring at younger ages than usual. Recognized causes of low peak bone mass include genetic causes, endocrine disorders, nutritional disorders, chronic diseases of childhood or adolescence, medications, and idiopathic factors.

The c.29T>C polymorphism of the transforming growth factor beta-1 (TGFB1) gene, bone mineral density and the occurrence of low-energy fractures in patients with inflammatory bowel disease

Gastrointestinal tract conditions are frequently associated with low bone mineral density and increased risk of fractures due to osteoporosis, the latter concerning particularly inflammatory bowel disease (IBD) patients. One of the candidate genes involved in osteoporosis is the transforming growth factor beta-1 (TGFB1) whose polymorphisms may be responsible for the development of this disease. The aim of this study was to analyse the frequency of TGFB1 polymorphic variants and determine the association between the c.29T>C TGFB1 polymorphism, and bone mineral density and fractures in IBD patients. The study subjects included 198 IBD patients [100 suffering from Crohn's disease (CD) and 98 from ulcerative colitis (UC)] and 41 healthy volunteers as a control group. Densitometric bone measurements were obtained using dual energy X-ray absorptiometry. The TGFB1 genotyping was conducted using restriction fragments length polymorphism. We conducted an analysis of genotype distribution's concordance with Hardy-Weinberg equilibrium. We found statistically significant differences in lumbar spine (L2-L4) and femoral neck BMD and T-scores between CD, UC and control subgroups. The distribution of TGFB1 polymorphic variants among CD and UC patients was concordant with Hardy-Weinberg equilibrium. There were no statistically significant differences in densitometric parameters (lumbar spine and femoral neck BMD, T-score, and Z-score) between carriers of different TGFB1 polymorphisms among IBD (CD and UC) patients nor among controls. We have found no statistically significant differences in the prevalence of low-energy fractures between groups of different TGFB1 polymorphic variant carriers. The allele dose effect, recessive effect and dominant effect analysis did not show an association between low-energy fractures and the TGFB1 polymorphisms among CD and UC patients. We have not observed an association between the c.29T>C TGFB1 polymorphic variant and the bone mineral density within the cancellous and cortical bones (L2-L4 and femoral neck, respectively), or the occurrence of fractures among the IBD patients and their family members.

Association of collagen type I alpha 1 +1245G/T polymorphism and osteoporosis risk in post-menopausal women: a meta-analysis

AIM

To fully understand the association between collagen type I alpha 1 (COL1A1) +1245G/T polymorphism and osteoporosis risk in post-menopausal women.

METHODS

We searched the electronic databases including PubMed, Embase and Cochrane library updated to January 2016, as well as printed articles. Studies were screened according to the predefined inclusion and exclusion criteria, and the included studies were further assessed by Clark scores system. Furthermore, the association between COL1A1 +1245G/T polymorphism and osteoporosis risk was assessed using odds ratios (ORs) and their 95% confidence intervals (95% CIs). Additionally, the meta-analysis was carried out using Review Manger 5.1 software (Cochrane Collaboration, Oxford, UK) and Stata 11.0 software (StataCorp, College Station, TX, USA).

RESULTS

A total of five studies, which contained 1557 subjects (including 458 osteoporosis patients, 269 osteopenic patients and 830 normal controls), were included. Further, the included studies achieved Clark scores no less than 5, indicating a moderate or high quality. The pooled effect size indicated that there was a significant association between COL1A1 +1245G/T polymorphism and osteoporosis risk only under a co-dominant model (GG vs. TT, OR = 2.45, 95% CI = 1.11-5.44, P = 0.03). Moreover, there was no significant correlation between COL1A1 +1245G/T polymorphism and osteopenic risk under each model (P > 0.05).

CONCLUSION

There might be a certain relationship between GG genotype of COL1A1 +1245G/T polymorphism and osteoporosis risk in post-menopausal women.

MRI Phenotyping of COL9A2/Trp2 and COL9A3/Trp3 Alleles in Lumbar Disc Disease: A Case-control Study in South-Western Iranian Population Reveals a Significant Trp3-Disease Association in Males

STUDY DESIGN

A case-control study of the Trp2/3 alleles of COL9A2/3 genes and their correlation with occurrence of Lumbar disc disease (DDD) as phenotyped by magnetic resonance imaging.

OBJECTIVE

To establish a better understanding of relationship between presence of said alleles and occurrence of DDD in South-Western Iranian population.

SUMMARY OF BACKGROUND DATA

A number of genetic predisposing factors have been identified in elevating the risk of developing DDD. Specifically, the Trp2 and Trp3 alleles of COL9A2 and COL9A3 genes have been suggested as DDD risk variants.

METHODS

A total of 108 patients (mean age = 41±11.8 yrs, range = 20-66 yrs) with 57 controls (mean age = 35±10.0 yrs, range = 20-58 yrs) participated in the study. The frequency of G/A polymorphism in COL9A2 gene on location 326 on chromosome 1 and G/A/C/ or T polymorphism in 103 location of COL9A3 gene on chromosome 20 was assessed using a PCR short-primer technique. Outcome measure was defined as presence of DDD on MRI. Odds ratios (OR) and 95% confidence intervals (CI) were used to assess the likelihood of DDD given occurrence of Trp2(3).

RESULTS

Each allele was present in both patients and controls. The Trp2 allele was positive in 28.5% of individuals (31.5% of patients; 22.8% of controls), OR 1.55 (0.71-3.56). The Trp3 allele, the frequency was 23.6% in all patients (26.9% patients; 17.5% controls), OR 1.72 (0.73-4.33). We observed a 5.8-fold increase in the odds of DDD in males when the Trp3 allele was present, OR 5.83 (1.09-9.98), P = 0.0273.

CONCLUSION

Both Trp2 and Trp3 alleles occurred more frequently compared with other studied ethnicities. The sampled Iranian population exhibited a similar Trp2 frequency to a Southern Chinese population, and Trp3 occurrence to Finnish and Greek population. We found that male patient were much more likely to develop DDD when Trp 3 was present.

LEVEL OF EVIDENCE

N/A.

Transcriptional Regulation of Frizzled-1 in Human Osteoblasts by Sp1

The wingless pathway has a powerful influence on bone metabolism and is a therapeutic target in skeletal disorders. Wingless signaling is mediated in part through the Frizzled (FZD) receptor family. FZD transcriptional regulation is poorly understood. Herein we tested the hypothesis that Sp1 plays an important role in the transcriptional regulation of FZD1 expression in osteoblasts and osteoblast mineralization. To test this hypothesis, we conducted FZD1 promoter assays in Saos2 cells with and without Sp1 overexpression. We found that Sp1 significantly up-regulates FZD1 promoter activity in Saos2 cells. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility shift (EMSA) assays identified a novel and functional Sp1 binding site at -44 to -40 from the translation start site in the FZD1 promoter. The Sp1-dependent activation of the FZD1 promoter was abolished by mithramycin A (MMA), an antibiotic affecting both Sp1 binding and Sp1 protein levels in Saos2 cells. Similarly, down-regulation of Sp1 in hFOB cells resulted in less FZD1 expression and lower alkaline phosphatase activity. Moreover, over-expression of Sp1 increased FZD1 expression and Saos2 cell mineralization while MMA decreased Sp1 and FZD1 expression and Saos2 cell mineralization. Knockdown of FZD1 prior to Sp1 overexpression partially abolished Sp1 stimulation of osteoblast differentiation markers. Taken together, our results suggest that Sp1 plays a role in human osteoblast differentiation and mineralization, which is at least partially mediated by Sp1-dependent transactivation of FZD1.

Raloxifene: A Selective Estrogen Receptor Modulator for the Prevention of Osteoporosis

Objective:

To review the efficacy and safety of the selective estrogen receptor modulator raloxifene hydrochloride in the prevention of osteoporosis.

Data Sources:

A MEDLINE search (January 1966–May 1998) and unpublished data obtained from the manufacturer were used to identify relevant studies and review articles. Additionally, bibliographies of selected articles were reviewed. Only English-language articles on human studies were obtained.

Study Selection:

Literature was reviewed to evaluate the pharmacology, pharmacokinetics, therapeutic use, adverse effects, and drug interactions of raloxifene. Additional relevant citations were used in the introduction material and clinical controversy section.

Data Extraction:

Clinical trials reviewing raloxifene for the prevention of osteoporosis were evaluated.

Data Synthesis:

Raloxifene hydrochloride is a partial estrogen agonist that displays both estrogenic and antiestrogenic effects. As a result of binding to estrogen receptors, raloxifene therapy, like estrogen treatment, causes positive changes in biochemical markers of bone turnover such as serum osteocalcin, serum alkaline phosphatase, urinary pyridinoline cross-links, and urinary calcium excretion. In addition, raloxifene increases bone mineral density. Furthermore, raloxifene reduces total serum cholesterol and serum low-density lipoprotein cholesterol. Raloxifene has no effect on serum high-density lipoprotein cholesterol. As a selective estrogen receptor modulator, raloxifene does not display the deleterious effects of estrogen in endometrial or breast tissue. The most common adverse effects are hot flashes and leg cramping.

Conclusions:

Clinical trials have found that raloxifene is effective in the prevention of osteoporosis, making the drug an alternative choice for the prevention of osteoporosis in patients who are concerned about the proliferative effects of estrogen replacement therapy on the endometrium or breast tissue. Raloxifene may not be a good alternative in women experiencing troublesome hot flushes during menopause. The use of raloxifene in the treatment of osteoporosis and in the prevention of breast cancer is currently being evaluated.

Genetics of pediatric bone strength

Osteoporosis is one of the most common chronic forms of disability in postmenopausal women and represents a major health burden around the world. Bone fragility is affected by bone mineral density (BMD), and, one of the most important factors in preventing osteoporosis is optimizing peak bone mass, which is achieved during growth in childhood and adolescence. BMD is a complex trait resulting from environmental and genetic factors. Genome-wide association studies have discovered robust genetic signals influencing BMD in adults, and similar studies have also been conducted to investigate the genetics of BMD in the pediatric setting. These latter studies have revealed that many adult osteoporosis-related loci also regulate BMD during growth. These investigations have the potential to profoundly impact public health and will allow for the eventual development of effective interventions for the prevention of osteoporosis.

The influence of osteoporosis in trauma

Osteoporosis is a descriptive term for a loss of bone mass and structure which predisposes to fracture in response to minimal trauma. These fractures cause pain, disability and significant mortality, with enormous resource costs to health and other services. Proximal femoral (hip) fractures account for most of the mortality and cost, and an estimated six million osteoporosis-related hip fractures occur world-wide each year, a number likely to increase dramatically due to changes in population demographics. The diagnosis of osteoporosis should be considered in all patients over the age of 50 years who sustain a fracture, unless there is obvious major trauma. Not only will this inform immediate management but it also allows measures aimed at prevention of further fractures to be implemented. Early surgery is often effective in limiting morbidity from osteoporotic fractures and in older people is best planned in collaboration with other health care professionals.

Association analysis of the COL1A1 polymorphism with bone mineral density and prevalent fractures in Polish postmenopausal women with osteoporosis

INTRODUCTION

Polymorphism in the promoter region of collagen type 1α (COL1A1) +1245G/T (Sp1, rs1800012) was in some studies shown to be relevant for bone mineral density (BMD) and low-energy fracture prediction. The aim of the study was to confirm this finding in a group of postmenopausal women diagnosed with osteoporosis.

MATERIAL AND METHODS

We investigated 311 Caucasian women (mean age: 65.2 ±9.39 years) either after low-energy fractures (regardless of the location) or meeting World Health Organization (WHO) criteria for osteoporosis. All patients underwent clinical examination in order to exclude secondary osteoporosis; hip and lumbar spine DEXA was performed (Lunar). The three genotypes of Sp1 polymorphism were determined by RFLP (restriction fragment length polymorphism).

RESULTS

Distribution of COL1A1 genotypes (SS/Ss/ss) agreed with Hardy-Weinberg equilibrium. No relation between COL1A1 genotypes and hip/L1-L4 BMD was found. Fractures were reported in 26.3% of women. Prevalence of low-energy fractures, regardless of the type, was 50.0% in ss genotype carriers, 26.4% in SS homozygotes and 23.7% in Ss heterozygotes. There was no statistically significant recessive or dominant effect of any Sp1 genotype on fracture prevalence (p = 0.613).

CONCLUSIONS

We failed to observe that COL1A1 Sp 1 genotypes contribute to BMD determination or are associated with prevalent low-energy fractures in a Polish cohort of postmenopausal osteoporotic women.

Low bone mineral density and vitamin d deficiency correlated with genetics and other bone markers in female Turkish immigrants in Germany

Patients with osteoporosis have a low bone mass resulting in an increased risk for bone fractures, morbidity and mortality. One hundred thirty-one female pre-menopausal participants (98 Turkish immigrants living in Germany in comparison with 33 age-matched healthy Germans) were recruited for this study which explored vitamin D deficiency and specific genetic modifications of bone metabolism. The subjects were investigated for their femoral and lumbar bone mineral density (BMD) by dual-energy X-ray absorptiometry (DEXA) of the right total femur and the lumbar spine. Serum levels of osteologic parameters were determined: parathormone (PTH), calcium (Ca), osteocalcin (OC), phosphate (P), alkaline phosphatase (AP), beta-crossLaps (CL), tartrate-resistant acid phosphatase isoform 5b (TRAP5b), and 25-vitamin D₃ (25-OH D₃). The Bsml- and Fokl-polymorphisms of the vitamin D receptor (VDR) gene and the collagen type I alpha 1 (COLIA1)-gene polymorphism were also genotyped. An extremely high prevalence of vitamin D deficiency could be found in the immigrant cohort (87.8 %). Osteoporosis but not osteopenia was more prevalent in this group. Among immigrants with osteoporosis, TRAP5b was elevated in 42.9 % and beta-CL in 28.6 %. Only the Fokl FF-genotype of the VDR polymorphism was significantly more prevalent among the Turkish women, Ff-genotyped immigrants showed significantly decreased BMD. A significant correlation between the COLIA1-gene polymorphism and BMD could not be identified in the two groups. Vitamin D deficiency and osteoporosis appear to be dominant and unrecognized problem among female Turkish immigrants in Germany. Therefore, in this population, osteologic parameters and BMD should be routinely analyzed and deficiencies be treated immediately.

The Developmental Origins of Osteoporosis

Osteoporosis is one of the most prevalent skeletal disorders and has enormous public health consequences due to the morbidity and mortality of the resulting fractures. This article discusses the developmental origins of osteoporosis and outlines some of the modifiable and non-modifiable risk factors in both intrauterine and postnatal life that contribute to the later onset of osteoporosis. Evidence for the effects of birth size and early growth in both preterm and term born infants are discussed and the role of epigenetics within the programming hypothesis is highlighted. This review provides compelling evidence for the developmental origins of osteoporosis and highlights the importance of osteoporosis prevention at all stages of the life course.

Polymorphisms Associated With Low Bone Mass and High Risk of Atraumatic Fracture

Osteoporosis is a serious disease characterized by high morbidity and mortality due to atraumatic fractures. In the pathogenesis of osteoporosis, except environment and internal factors, such as hormonal imbalance and genetic background, are also in play. In this study candidate genes for osteoporosis were classified according to metabolic or hormonal pathways, which regulate bone mineral density and bone quality (estrogen, RANKL/RANK/OPG axis, mevalonate, the canonical circuit and genes regulating the vitamin D system). COL1A1 and/or COL1A2 genes, which encode formation of the procollagen 1 molecule, were also studied. Mutations in these genes are well-known causes of the inborn disease ‘osteogenesis imperfecta’. In addition to this, polymorphisms in COL1A1 and/or COL1A2 have been found to be associated with parameters of bone quality in adult subjects. The authors discuss the perspectives for the practical utilization of pharmacogenetics (identification of single candidate genes using PCR) and pharmacogenomics (using genome wide association studies (GWAS) to choose optimal treatment for osteoporosis). Potential predictors of antiresorptive therapy efficacy include the following well established genes: ER, FDPS, Cyp19A1, VDR, Col1A1, and Col1A2, as well as the gene for the canonical (Wnt) pathway. Unfortunately, the positive outcomes seen in most association studies have not been confirmed by other researchers. The controversial results could be explained by the use of different methodological approaches in individual studies (different sample size, homogeneity of investigated groups, ethnic differences, or linkage disequilibrium between genes). The key pitfall of association studies is the low variability (7-10 %) of bone phenotypes associated with the investigated genes. Nevertheless, the identification of new genes and the verification of their association with bone density and/or quality (using both PCR and GWAS), remain a great challenge in the optimal prevention and treatment of osteoporosis.

Degenerated intervertebral disc prolapse and its association of collagen I alpha 1 Spl gene polymorphism: A preliminary case control study of Indian population

BACKGROUND

Degenerated disc disease (DDD) is a common disorder responsible for increased morbidity in a productive age group. Its etiology is multifactorial and genetic factors have been predominantly implicated. Disc prolapse results due to tear in the annulus, which is a fibrous structure composed largely of type I collagen. Functional polymorphism at the Sp1 site of the collagen I alpha 1 (COL1A1) gene has shown a positive association with DDD in Dutch and Greek populations. The purpose of this study was to assess COL1A1 Sp1 gene polymorphism in the Indian population.

MATERIALS AND METHODS

Fifty clinically and radiologically proven patients with disc prolapse requiring surgery were included as cases and 50 healthy, age-matched volunteers served as controls. After isolating DNA from their blood sample, genotyping for COL1A1 polymorphism (rs1800012) was performed and identified as GG, GT, and TT.

RESULTS

The mean age and body mass index in cases and controls were similar. 76% of the patients were males. The most common site of disc degeneration was L4-L5 (36%), followed by L5-S1 (34%). Homozygous-GG, heterozygous GT, and homozygous TT genotypes were seen in 38 (76%), 10 (20%) and 2 (4%) cases respectively, controls had similar percentage of genotypes as well. The alleles in cases and the control group showed no significant difference (P = 0.6744) and followed the Hardy-Weinberg Equilibrium in the study population.

CONCLUSION

The COL1A1 (rs1800012) is in Hardy-Weinberg equilibrium in the present subset of Indian population. But taken as a single factor, it was not found to be associated with DDD in this preliminary study. Disc degeneration is multifactorial and also anticipated to be a result of multiple genes involvement and gene-gene interaction.

Combined effects of collagen type I alpha1 (COL1A1) Sp1 polymorphism and osteoporosis risk factors on bone mineral density in Turkish postmenopausal women

Identification of risk factors for osteoporosis has been essential for understanding the development of osteoporosis. The collagen type I alpha1 (COL1A1) gene is suggested to be implicated in reduced bone mineral density (BMD) in osteoporosis. In the present study, the investigation of the effects of Sp1 polymorphic variants of COL1A1 gene on BMD values, and the determination of the association between COL1A1 Sp1 gene variants and osteoporosis risk factors in the context of gene-environment interaction in Turkish postmenopausal women were aimed. For the detection of COL1A1 Sp1 polymorphism, PCR-RFLP techniques have been used. BMD for lumbar spine (L1-L4) and hip (femoral neck and total hip) was measured by DXA. This study was carried out using a sample of 254 postmenopausal women. We observed a trend decrease in BMD values in the subjects with "ss" genotype having lower BMD of lumbar spine, femoral neck and total hip than those with "SS" and "Ss" genotype, however the differences did not reach statistical significance (P>0.05). We also found that the frequencies of the BMD under mean values at the femoral neck (57.5%) and total hip (76.2%) increased considerably in the subjects carrying "Ss/ss" genotypes in combination of having family history of osteoporosis (61.5% for femoral neck) and smoking history (90.0% for total hip). This population-based study indicates that COL1A1 Sp1 polymorphism may contribute to the development of osteoporosis in combination of osteoporosis risk factors in Turkish postmenopausal women.

Genetic analysis of the relationship between bone mineral density and low-density lipoprotein receptor-related protein 5 gene polymorphisms

Background

A number of studies have examined the association between the polymorphisms of the low-density lipoprotein receptor-related protein 5 gene (LRP5), but previous results have been inconclusive. Thus we performed a meta-analysis of studies on the association between the LRP5 polymorphisms and bone mineral density (BMD) to assess their pooled effects.

Methods

Published literature from PubMed, EMBASE and ISI web of science were searched for eligible publications. Weighted mean difference (WMD) and 95% confidence interval (CI) was calculated using fixed- or random-effects model.

Results

A total of 19 studies with 25773 subjects were considered in this meta-analysis. Of them, 17 examined the association between the A1330V polymorphism and BMD, 8 were focused on the V667M polymorphism, and 2 analyzed the Q89R polymorphism. Individuals with the A1330V AA genotype showed significantly higher BMD than those with the AV/VV genotypes [at lumbar spine (LS): WMD = 0.02g/cm², 95% CI = 0.01-0.03, P < 10^-4; at femur neck (FN): WMD = 0.01g/cm², 95% CI = 0.00-0.02, P = 0.01] or VV genotype (at LS: WMD = 0.02g/cm², 95% CI = 0.01-0.04, P = 0.01). Significant associations were also detected in the analysis for V667M (VV vs. VM/MM: WMD at LS = 0.02g/cm², 95% CI = 0.02-0.03, P < 10^-5; WMD at FN = 0.01g/cm², 95% CI = 0.01-0.02, P = 0.0002). As for Q89R, subjects with the QQ genotype tended to have higher BMD than those with the QR/RR genotypes at FN (WMD = 0.03g/cm², 95% CI = 0.01-0.05, P = 0.005).

Conclusion

This meta-analysis demonstrated that the LRP5 polymorphisms may be modestly associated with BMD of LS and FN.

Screening of osteoprotegerin-related feature genes in osteoporosis and functional analysis with DNA microarray

Background

Osteoporosis affects 200 million people worldwide and places an enormous economic burden on society. We aim to identify the feature genes that are related to osteoprotegerin in osteoporosis and to perform function analysis with DNA microarray from human bone marrow.

Methods

We downloaded the gene expression profile GSE35957 from Gene Expression Omnibus database including nine gene chips from bone marrow mesenchymal stem cells of five osteoporotic and four non-osteoporotic subjects. The differentially expressed genes between normal and disease samples were identified by LIMMA package in R language. The interactions among the osteoprotegerin gene (OPG) and differentially expressed genes were searched and visualized by Cytoscape. MCODE and Bingo were used to perform module analysis. Finally, GENECODIS was used to obtain enriched pathways of genes in an interaction network.

Results

A total of 656 genes were identified as differentially expressed genes between osteoporotic and non-osteoporotic samples. IL17RC, COL1A1, and ESR1 were identified to interact with OPG directly from the protein-protein interaction network. A module containing ERS1 was screened out, and this module was most significantly enriched in organ development. Pathway enrichment analysis suggested genes in the interaction network were related to focal adhesion.

Conclusions

The expression pattern of IL17RC, COL1A1, and ESR1 can be useful in osteoporosis detection, which may help in identifying those populations at high risk for osteoporosis, and in directing treatment of osteoporosis.

Postmenopausal women with osteoporosis and osteoarthritis show different microstructural characteristics of trabecular bone in proximal tibia using high-resolution magnetic resonance imaging at 3 tesla

Background

Osteoporosis (OP) and osteoarthritis (OA) are two common musculoskeletal disorders that affect the quality of life in aged people. An inverse relationship between OP and OA was proposed four decades ago. However, the difference in microstructure of the trabecular bone of these two disorders by high-resolution MRI (HR-MRI) has not been compared. The primary objective of the study is to explain the actual relationship between OA and OP based on differences between bone microstructure of these two diseases. The secondary objectives are to find out the significance of Euler number and its relationship with other structural parameters, and important role of HR-MRI to reveal the microstructure of trabecular bone directly.

Methods

Totally, 30 women with OP and 30 women with OA (n = 60) were included in this study. Primary OA of hip, knee, as well as spinal arthrosis were diagnosed according to plain X-ray film findings. Osteoporosis was defined based on the latest criteria of World Health Organization (WHO). Structural and textural parameters derived from HR-MRI images of proximal tibia were calculated and compared with special software.

Results

There were significant differences in apparent bone volume fraction, trabecular thickness, mean roundness, Euler number, entropy and inverse different moment between OP and OA patients. In OP group, apparent trabecular separation (Tb.Sp), inertia, absolute value and contrast were positively correlated with Euler number, whereas apparent trabecular number (Tb.N), mean trabecular area, inverse difference and inverse different moment were negatively correlated. Apparent trabecular bone volume fraction (BV/TV), mean trabecular area, mean trabecular perimeter and mean skeleton length negatively correlated with Euler number in OA group. Inverse different moment was the texture parameter, which influenced bone mineral density (BMD) of femoral neck, meanwhile contrast influenced BMD of both great trochanter and Ward’s triangle in OP group. While in OA group, Euler number was the exclusive parameter, which affected BMD of femoral neck and Ward’s triangle.

Conclusions

We found significant differences in microstructure parameters derived from HR-MRI images between postmenopausal women with OP and OA. It convincingly supports the hypothesis that there might be an inverse relationship between OP and OA.

JAG1 and COL1A1 polymorphisms and haplotypes in relation to bone mineral density variations in postmenopausal Mexican-Mestizo Women

Osteoporosis is characterized by low bone mineral density (BMD). One of the most important factors that influence BMD is the genetic contribution. The collagen type 1 alpha 1 (COL1A1) and the JAGGED (JAG1) have been investigated in relation to BMD. The aim of this study was to investigate the possible association between two single-nucleotide polymorphisms (SNPs) of COL1A1, their haplotypes, and one SNP of JAG1 with BMD in postmenopausal Mexican-Mestizo women. Seven hundred and fifty unrelated postmenopausal women were included. Risk factors were recorded and BMD was measured in lumbar spine, total hip, and femoral neck by dual-energy X-ray absorptiometry. DNA was obtained from blood leukocytes. Two SNPs in COL1A1 (rs1800012 and rs1107946) and one in JAG1 (rs2273061) were studied. Real-time PCR allelic discrimination was used for genotyping. The differences between the means of the BMDs according to genotype were analyzed with covariance. Deviations from Hardy-Weinberg equilibrium were tested. Pairwise linkage disequilibrium between single nucleotide polymorphisms was calculated by direct correlation r (2), and haplotype analysis of COL1A1 was conducted. Under a dominant model, the rs1800012 polymorphism of the COL1A1 showed an association with BMD of the lumbar spine (P = 0.021). In addition, analysis of the haplotype of COL1A1 showed that the G-G haplotype presented a higher BMD in lumbar spine. We did not find an association between the s1107946 and rs2273061 polymorphisms of the COL1A1 and JAG1, respectively. Our results suggest that the rs1800012 polymorphism of the COL1A1, in addition to one haplotype, were significantly associated with BMD variation in Mexican-Mestizo postmenopausal women.

The future of pharmacogenetics for osteoporosis

The possibility to predict the outcome of medical treatments, both in terms of efficacy and development of adverse effects, is the main goal of modern personalized medicine. The principal aim of pharmacogenetics is to design specific predictive genetic tests, to be performed prior to any drug treatment, and to tailor the therapy for each patient based on the results of these tests. Few pharmacogenetic tests are today validated and commonly applied in clinical practice, and none in the area of osteoporosis and bone disorders. Surely, the complex regulation of bone metabolism and the involvement of numerous different molecular pathways makes it difficult to individuate responsible genes and polymorphisms involved in the modulation of anti-osteoporotic drug response and, subsequently, in designing specific predictive analyses.

Genetics of lumbar disk degeneration: technology, study designs, and risk factors

Lumbar disk degeneration (LDD) is a common musculoskeletal condition. Genetic risk factors have been suggested to play a major role in its cause. This article reviews the main research strategies that have been used to study the genetics of LDD, and the genes that thus far have been identified to influence susceptibility to LDD. With the rapid progress in genomic technologies, further advances in the genetics of LDD are expected in the next few years.

Effects of COLIA1 polymorphisms and haplotypes on perimenopausal bone mass, postmenopausal bone loss and fracture risk

One thousand seven hundred seventeen perimenopausal women from the Danish Osteoporosis Prevention Study were genotyped for the -1997G/T, -1663indelT and +1245G/T polymorphisms in the COLIA1 gen. We found that the -1997T allele and a haplotype containing it were associated with reduced bone mineral density (BMD) and increased bone turnover at menopause and after 10 years of follow-up.

INTRODUCTION

We wanted to investigate whether the -1997G/T, -1663indelT and +1245G/T polymorphisms in the COLIA1 gene are associated with perimenopausal bone mass, early postmenopausal bone loss and interact with hormone treatment.

METHODS

One thousand seven hundred seventeen perimenopausal women from the Danish Osteoporosis Prevention Study were genotyped, and haplotypes were determined. BMD was examined by dual X-ray absorptiometry.

RESULTS

Women carrying the -1997T variant had lower BMD at all measured sites: lumbar spine BMD 1.030 ± 0.137 g/cm(2), 1.016 ± 0.147 g/cm(2) and 0.988 ± 0.124 g/cm(2) in women with the GG, GT and TT genotypes, respectively (p < 0.05) and total hip BMD 0.921 ± 0.116 g/cm(2), 0.904 ± 0.123 g/cm(2) and 0.887 ± 0.109 g/cm(2) in women with the GG, GT and TT genotypes, respectively (p = 0.01). The effect remained after 10 years although statistical significance was lost. Haplotype 3 (-1997T-1663ins + 1245G) was associated with lower bone mass and higher levels of bone turnover. Compared with haplotype 1, haplotype 3 carriers had lower BMD at the lumbar spine, femoral neck and total hip by 0.016 ± 0.007 g/cm(2), 0.015 ± 0.006 g/cm(2) and 0.017 ± 0.006 g/cm(2), respectively (p < 0.05-0.005). No association with postmenopausal changes in bone mass and fracture risk and no overall interaction with the effects of hormone therapy could be demonstrated for any of the polymorphisms in COLIA1.

CONCLUSIONS

The -1997G/T polymorphism and haplotype 3 are significantly associated with perimenopausal bone mass, and these effects were sustained up to 10 years after menopause. No association between the -1663indelT or +1245G/T polymorphisms and peri- or postmenopausal bone mass could be demonstrated.

Association of estrogen receptor alpha and collagen type I alpha 1 gene polymorphisms with bone mineral density in postmenopausal women

In this study, ERα gene PvuII and XbaI polymorphisms and COL1A1 gene Sp1 polymorphisms in postmenopausal women were compared with lumbar vertebra and femoral neck BMD values. In conclusion, it was designated that PvuII polymorphism was effective on average lumbar vertebra BMD value in postmenopausal women of our study group.

INTRODUCTION

Bone mineral density (BMD), the major determinant of osteoporotic fracture risk, has a strong genetic component. Several candidate gene polymorphisms have been implicated in the regulation of this process. In this study, the relationship among BMD values of lumbar vertebra and femoral neck and ERα gene PvuII and XbaI polymorphisms and COL1A1 gene Sp1 polymorphism in 126 postmenopausal women (30 normal, 46 osteopenic, and 50 osteoporotic in terms of bone mineral density) was researched.

METHODS

The ERα gene PvuII and XbaI genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) whereas the COL1A1 gene Sp1 genotype was determined by real-time PCR. BMDs at the lumbar spine (vertebrae L1-L4) and hip (femur neck) were measured by dual-energy X-ray absorptiometry.

RESULTS

According to our study results, the significant difference was found in women with normal, osteopenic, and osteoporotic bone mass in terms of ERα gene PvuII polymorphism "pp" genotype frequency. The "pp" genotype frequency was significantly lower in women with normal bone mass. Average lumbar vertebra BMD value of women with "PP" genotype was significantly higher than that with "pp" genotype. On the other hand, in the evaluations on ERα gene XbaI polymorphism and COL1A1 gene Sp1 polymorphism, it was noted that there was no difference in terms of average BMD values, genotype, and allele frequencies among groups.

CONCLUSION

In conclusion, it was designated that ERα gene PvuII polymorphism was effective on average lumbar vertebra BMD value in postmenopausal women of our study group.

Polymorphisms in the 5' flank of COL1A1 gene and osteoporosis: meta-analysis of published studies

A meta-analysis of studies was conducted involving 24,511 participants with 7,864 fractures in which polymorphisms in the 5' flank of COL1A1 (rs1107946, rs2412298, and rs1800012) were related to osteoporosis phenotypes. Polymorphisms of all three sites were associated with BMD, and rs1800012 was associated with fracture but effect sizes were modest.

INTRODUCTION AND HYPOTHESIS

Polymorphisms in the 5' flank of COL1A1 gene have been implicated as genetic markers for susceptibility to osteoporosis, but previous studies have yielded conflicting results.

METHODS

We conducted a meta-analysis of 32 studies including 24,511 participants and 7,864 fractures in which alleles at the -1997G/T (rs1107946), -1663in/delT (rs2412298), and Sp1 binding site polymorphisms (rs1800012) of COL1A1 had been related to bone mineral density (BMD) or fracture.

RESULTS

For the Sp1 polymorphism, BMD values in TT homozygotes were 0.13 units [95% CI, 0.03 to 0.24] lower at the spine (p = 0.01) and 0.16 units [0.10 to 0.23] lower at the hip (p = 1 x 10⁻⁶) than GG homozygotes. Clinical fractures were 1.31-fold [1.04-1.65] increased in TT homozygotes (p = 0.02) and vertebral fractures were 1.34-fold [1.01-1.77] increased (p = 0.04). We also observed associations between spine BMD and allelic variants at the -1997G/T (p = 0.05) and the -1663indelT (p = 0.009) sites. We found no association between alleles at the -1997G/T or -1663indelT sites and fracture but power was limited.

CONCLUSIONS

The COL1A1 Sp1 polymorphism is associated with a modest reduction in BMD and an increased risk of fracture, although we cannot fully exclude the possibility that the results may have been influenced by publication bias. Further studies are required to fully evaluate the contribution of the -1997G/T and -1663in/delT sites to these phenotypes and to determine if they interact with the Sp1 polymorphism to regulate susceptibility to osteoporosis.

An SP1-binding site polymorphism in the COLIAI gene and osteoporosis in Egyptian patients with thalassemia major

β-Thalassemia major is an inherited blood disorder, which mainly affects the Mediterranean region. Osteoporosis represents an important cause of morbidity in β-thalassemia major and its pathogenesis has not been completely clarified. Genetic factors play an important role in the pathogenesis of osteoporosis and several candidate gene polymorphisms have been implicated in the regulation of this process. A G→T polymorphism in the regulatory region of the collagen type I alpha 1 (COLIAI) gene at a recognition site for transcription factor Sp1 has been strongly associated with osteoporosis. The aim of the present study was to examine the distribution of COLIAI polymorphism and its relationship with bone mineral density (BMD) at the lumbar spine and femur in patients and controls. In this study, the G→T polymorphism was detected in 31 Egyptian β-thalassemia major patients and 20 healthy controls and its possible association with BMD was investigated. Alleles S and s were detected by the presence of a G or T nucleotide, respectively, in a regulatory site of the COLIAI gene using polymerase chain reaction (PCR). A total of 80.6% of the β-thalassemia patients were homozygous for G/G (SS) and 19.4% were heterozygotes for G/T (Ss) polymorphism. There was no ss genotype in our patients. In the control group, 70 and 30% had SS and Ss genotypes, respectively. There was no significant difference between Z-score of patients with SS and Ss at head of femur (P = 1) or at lumbar spine (P = 0.48). Conclusion Our results raise the possibility that genotyping at the Sp1 site could be of clinical value in identifying the thalassemic patients at risk of developing osteoporosis.

Genetic variants in the apelin system and blood pressure responses to dietary sodium interventions: a family-based association study

OBJECTIVE

We examined the association between genetic variants in the apelin system and blood pressure (BP) responses to low-sodium and high-sodium interventions in the GenSalt Study.

METHODS

A 7-day low-sodium intervention (51.3 mmol sodium per day) followed by a 7-day high-sodium intervention (307.8 mmol sodium per day) was conducted among 1906 participants from 637 Han Chinese families. BP measurements were obtained at baseline and following each intervention using a random-zero sphygmomanometer. Twenty-three single nucleotide polymorphisms (SNPs), including both tag and functional SNPs, were selected from three candidate genes (APLN, APLNR, and ACE2). Single marker and haplotype analyses were conducted using the Family Based Association Test program. The false discovery rate method was used to correct for multiple testing.

RESULTS

SNPs rs2282623 and rs746886 of the APLNR gene were significantly associated with DBP (both P = 0.002) and mean arterial pressure (MAP) (P = 0.001 and 0.005, respectively) responses to low-sodium intervention. Six SNPs of the ACE2 gene were significantly associated with SBP, DBP, or MAP responses to low-sodium intervention. Three of them, rs1514283, rs1514282, and rs4646176, were also significantly associated with MAP response to high-sodium intervention (all P <or= 0.006). Haplotype analysis indicated the A-T-T haplotype of APLNR SNPs rs721608-rs2282623-rs746886 was associated with decreased DBP and MAP responses to low-sodium intervention (P = 0.001 and 0.003, respectively), whereas G-C-C was associated with increased SBP and MAP responses to high-sodium intervention (P = 0.004 and 0.01, respectively).

CONCLUSION

This large family-based study indicates that genetic variants in the APLNR and ACE2 genes are significantly associated with BP responses to dietary sodium intervention.

Genetic predisposition for femoral neck stress fractures in military conscripts

BACKGROUND

Stress fractures are a significant problem among athletes and soldiers and may result in devastating complications or even permanent handicap. Genetic factors may increase the risk, but no major susceptibility genes have been identified. The purpose of this study was to search for possible genetic factors predisposing military conscripts to femoral neck stress fractures.

RESULTS

Eight genes involved in bone metabolism or pathology (COL1A1, COL1A2, OPG, ESR1, VDR, CTR, LRP5, IL-6) were examined in 72 military conscripts with a femoral neck stress fracture and 120 controls. The risk of femoral neck stress fracture was significantly higher in subjects with low weight and body mass index (BMI). An interaction between the CTR (rs1801197) minor allele C and the VDR C-A haplotype was observed, and subjects lacking the C allele in CTR and/or the C-A haplotype in VDR had a 3-fold higher risk of stress fracture than subjects carrying both (OR = 3.22, 95% CI 1.38-7.49, p = 0.007). In addition, the LRP5 haplotype A-G-G-C alone and in combination with the VDR haplotype C-A was associated with stress fractures through reduced body weight and BMI.

CONCLUSIONS

Our findings suggest that genetic factors play a role in the development of stress fractures in individuals subjected to heavy exercise and mechanical loading. The present results can be applied to the design of future studies that will further elucidate the genetics of stress fractures.

Genetics of osteoporosis

Osteoporosis is a common disease with a strong genetic component characterized by reduced bone mass, defects in the microarchitecture of bone tissue, and an increased risk of fragility fractures. Twin and family studies have shown high heritability of bone mineral density (BMD) and other determinants of fracture risk such as ultrasound properties of bone, skeletal geometry, and bone turnover. Osteoporotic fractures also have a heritable component, but this reduces with age as environmental factors such as risk of falling come into play. Susceptibility to osteoporosis is governed by many different genetic variants and their interaction with environmental factors such as diet and exercise. Notable successes in identification of genes that regulate BMD have come from the study of rare Mendelian bone diseases characterized by major abnormalities of bone mass where variants of large effect size are operative. Genome-wide association studies have also identified common genetic variants of small effect size that contribute to regulation of BMD and fracture risk in the general population. In many cases, the loci and genes identified by these studies had not previously been suspected to play a role in bone metabolism. Although there has been extensive progress in identifying the genes and loci that contribute to the regulation of BMD and fracture over the past 15 yr, most of the genetic variants that regulate these phenotypes remain to be discovered.

Identification of non-synonymous polymorphisms in the WDSOF1 gene as novel susceptibility markers for low bone mineral density in Japanese postmenopausal women

Genetic factors are important for the development of osteoporosis. During the search for novel markers of single-nucleotide polymorphisms (SNPs) associated with bone mineral density (BMD) by performing a large-scale SNP screen with 251 Japanese postmenopausal women utilizing 50K SNP array, we here focused on the rs1370005 in the WD repeats and SOF1 domain-containing (WDSOF1) gene because we could found common non-synonymous variants in this WDSOF1 gene. The analysis of linkage disequilibrium (LD) in the WDSOF1 gene revealed that rs1370005 and 3 other non-synonymous SNPs (Arg47Ser, Pro108Leu and Ile194Val) lie in a 30-kb region of high LD. Quantitative real-time PCR (qRT-PCR) analysis showed that WDSOF1 mRNA was expressed in mouse primary osteoblasts and osteoclasts, suggesting that WDSOF1 plays some roles in the bone metabolism. We examined the 3 non-synonymous SNPs in WDSOF1 gene in 750 Japanese postmenopausal women. A trend test showed that Arg47Ser, Pro108Leu, and Ile194Val genotypes were significant associated with total body BMD (Arg47Ser; P=0.021, Pro108Leu; P=0.022 and Ile194Val; P=0.009). We also compared Z scores for total body BMD between the subjects bearing at least one minor allele and those lacking the minor allele using unpaired t test. Subjects with the one or two minor alleles had significantly lower Z scores for total body BMD (Arg47Ser; P=0.010, Pro108Leu; P=0.019 and Ile194Val; P=0.003). The present study suggests that these non-synonymous WDSOF1 polymorphisms play a role in the genetic susceptibility to osteoporosis.

Micro-CT and mechanical evaluation of subchondral trabecular bone structure between postmenopausal women with osteoarthritis and osteoporosis

SUMMARY

An inverse relationship between osteoarthritis and osteoporosis has been debated over years. The microstructure of the femoral heads from postmenopausal osteoarthritic and osteoporotic women was evaluated with micro-CT. Significant differences were observed in microstructural parameters between them. Different microstructure might relate to the opposite bone defects in osteoarthritis and osteoporosis.

INTRODUCTION

This study was undertaken to verify the inverse relationship between osteoarthritis (OA) and osteoporosis (OP) by comparing the structural and mechanical indices.

METHODS

Femoral head specimens were obtained from 17 postmenopausal women (OA, n = 8; OP, n = 9) during hip surgery. The microstructural parameters were measured with micro-CT. Mechanical test was performed after bone cube scanning.

RESULTS

Significant difference in bone volume fraction (BV/TV) and trabecular thickness was noted between OA and OP groups. Structure model index decreased in OA, and increased in OP. The higher apparent density (AD) and lower material density (MD) were also shown in OA. Different from OP, positive correlation were noted between connectivity density and mechanical indices in OA. In OA group, BV/TV was associated with Young's modulus and AD, while trabecular number was the only parameter that correlated with MD. However, in OP group, only BV/TV correlated with yield strength, AD, and MD.

CONCLUSIONS

We observed the difference in microstructure between postmenopausal women with OA and OP, which might relate to the opposite bone defects in OA and OP. BV/TV might play an important role in mechanical properties of the subchondral bone in either OA or OP.

Polymorphism in interleukin-6 gene is associated with bone mineral density in patients with adolescent idiopathic scoliosis

Low bone mass and osteopenia have been described in the axial and peripheral skeleton of patients with adolescent idiopathic scoliosis (AIS). Recently, many studies have shown that gene polymorphism is related to osteoporosis. However, no studies have linked the association between IL6 gene polymorphism and bone mass in AIS. This study examined the association between bone mass and IL6 gene polymorphism in 198 girls with AIS. The polymorphisms of IL6-597 G→A, IL6-572 G→C and IL6-174 G→A and the bone mineral density in the lumbar spine and femoral neck were analysed and compared with their levels in healthy controls. The mean bone mineral density at both sites in patients with AIS was decreased compared with controls (p = 0.0022 and p = 0.0013, respectively). Comparison of genotype frequencies between AIS and healthy controls revealed a statistically significant difference in IL6-572 G→C polymorphism (p = 0.0305). There was a significant association between the IL6-572 G→C polymorphism and bone mineral density in the lumbar spine, with the CC genotype significantly higher with the GC (p = 0.0124) or GG (p = 0.0066) genotypes.

These results suggest that the IL6-572 G→C polymorphism is associated with bone mineral density in the lumbar spine in Korean girls with AIS.

Common variants of the neuropeptide expressing tachykinin genes and susceptibility to asthma: a case-control study

Since tachykinins appear to be involved in the pathogenesis of allergic asthma, we investigated a possible association between 28 single nucleotide polymorphisms of the tachykinin genes TAC1, TAC3 and TAC4, and asthma susceptibility. A case-control study was conducted on 102 patients and 100 healthy subjects from the Canary Islands (Spain). A significant association with asthma was observed for two SNPs: rs2291855 in the TAC3 gene conferring asthma protection (Odds ratio [OR]: 0.46; 95% Confidence Interval [CI]: 0.22-0.97; P=0.038), and rs4794068 in the TAC4 gene associated with an increased risk for asthma (OR: 1.94; 95% CI: 1.06-3.54; P=0.03). The present study represents a preliminary step in elucidating the association between tachykinin gene polymorphisms and asthma susceptibility.

Polymorphism in vitamin D receptor is associated with bone mineral density in patients with adolescent idiopathic scoliosis

Low bone mass and osteopenia have been reported in the axial and peripheral skeleton of adolescent idiopathic scoliosis (AIS) patients. Furthermore, several recent studies have shown that gene polymorphisms are related to osteoporosis. However, no study has yet linked polymorphisms in the vitamin D receptor (VDR) gene and bone mass in AIS. Accordingly, the authors examined the association between bone mass and VDR gene polymorphisms in 198 girls diagnosed with AIS. The VDR BsmI (rs1544410), FokI (rs2228670) and Cdx2 (rs11568820) polymorphisms and bone mineral density at the lumbar spine (LSBMD) and femoral neck (FNBMD) were analyzed and compared to their levels in healthy controls. Mean LSBMD and FNBMD in AIS patients were lower than in age- and sex-matched healthy controls (P = 0.0022 and P = 0.0013, respectively). A comparison of genotype frequencies in AIS patients and controls revealed a significant difference for the BsmI polymorphism only (P = 0.0054). Furthermore, a significant association was found between the VDR BsmI polymorphism and LSBMD. In particular, LSBMD in AIS patients with the AA genotype was found to be significantly lower than in patients with the GA (P < 0.05) or GG (P < 0.01) genotypes. However, no significant association was found between LSBMD or FNBMD and the VDR FokI or Cdx2 polymorphisms. These results suggest that the VDR BsmI polymorphism is associated with LSBMD in girls with AIS.

Genetic determinants of osteoporosis: common bases to cardiovascular diseases?

Osteoporosis is the most common and serious age-related skeletal disorder, characterized by a low bone mass and bone microarchitectural deterioration, with a consequent increase in bone fragility and susceptibility to spontaneous fractures, and it represents a major worldwide health care problem with important implications for health care costs, morbidity and mortality. Today is well accepted that osteoporosis is a multifactorial disorder caused by the interaction between environment and genes that singularly exert modest effects on bone mass and other aspects of bone strength and fracture risk. The individuation of genetic factors responsible for osteoporosis predisposition and development is fundamental for the disease prevention and for the setting of novel therapies, before fracture occurrence. In the last decades the interest of the Scientific Community has been concentrated in the understanding the genetic bases of this disease but with controversial and/or inconclusive results. This review tries to summarize data on the most representative osteoporosis candidate genes. Moreover, since recently osteoporosis and cardiovascular diseases have shown to share common physiopathological mechanisms, this review also provides information on the current understanding of osteoporosis and cardiovascular diseases common genetic bases.