Bone mineral density in relation to polymorphism at the vitamin D receptor gene locus

Prevalence and effects of Vitamin D receptor polymorphism on bone mineral density and metabolism in patients with systemic sclerosis: a preliminary study

Patients with systemic sclerosis (SSc) have a disproportionately high prevalence of reduced bone mineral density (BMD). Polymorphisms of the vitamin D receptor (VDR) gene have been associated with osteoporosis in patients with autoimmune diseases. The aim of this study was to investigate the prevalence and possible effects of VDR polymorphism on BMD and bone metabolism in patients with SSc. In patients with SSc measurement of BMD was performed using dual-energy X-ray absorptiometry. VDR polymorphisms (FokI, BsmI) were genotyped using restriction fragment length polymorphism analysis. Markers of bone metabolism (calcium, osteocalcin, β-crosslaps) were determined. Primary endpoint was the prevalence of VDR gene polymorphisms and the association with reduced BMD. Secondary endpoints included associations between bone metabolism and VDR gene polymorphism. 79 Caucasian patients with SSc were included. Overall, 83.5% had reduced BMD (51.9% osteopenia, 31.6% osteoporosis). The prevalence of VDR gene polymorphism (73% BsmI, 77% FokI) was comparable to studies in healthy and rheumatic populations. The homozygous presence of FokI polymorphism, but not BsmI, was significantly associated with reduced axial BMD. Fokl polymorphism was significantly associated with reduced CTX levels, although changes remained within the reference limits. VDR polymorphisms can frequently be found in patients with SSc in comparable prevalence to healthy and rheumatic populations. The homozygous presence of FokI polymorphism, but not BsmI, was significantly associated with reduced axial BMD. This could be a possible contributor for the high prevalence of reduced BMD in 83.5% of patients with SSc in this study.Trial registration. DRKS00032768, date: 05.10.2023, retrospectively registered.

Vitamin D Receptor Gene Variants Susceptible to Osteoporosis in Arab Post-Menopausal Women

Post-menopausal osteoporosis (PMO) is a multifactorial bone disorder in elderly women. Various vitamin D receptor (VDR) gene variants have been studied and associated with osteoporosis in other populations, but not in a homogenous Arab ethnic group. Herein, the current study explores the association between VDR polymorphisms and susceptibility to osteoporosis in Saudi postmenopausal women. In total, 600 Saudi postmenopausal women (N = 300 osteoporosis; N = 300 control) were genotyped for VDR gene variants (rs7975232, rs1544410, rs731236) using TaqMan^® SNP genotyping assays. Bone mineral density (BMD) for the lumbar spine and femur was assessed using dual-energy X-ray absorptiometry (DEXA). The heterozygous frequency distributions AC of rs7975232, CT of rs1544410, and AG of rs731236 were significantly higher in the osteoporosis group than controls (p < 0.05). Heterozygous AC of rs7975232 (1.6; 95% CI 1.1–2.3; p < 0.023), CT of rs1544410 (1.6; 95% CI 1.1–2.4; p < 0.022), and AG of rs731236 (1.6; 95% CI 1.1–2.4; p < 0.024) were significantly associated with increased risk of osteoporosis, independent of age and BMI. In conclusion, VDR gene variants rs7975232, rs1544410, rs731236 had a significant effect on BMD and were associated with osteoporosis risk in Saudi postmenopausal women.

Association Between Low Bone Mineral Density Risk Factors and Estrogen Receptor α Gene Polymorphisms in Japanese Female Athletes

Background: The relationship between bone metabolism-related gene polymorphisms and low bone mineral density (BMD) risk factors in female athletes is unclear. This study aimed at investigating whether the sensitivity of low BMD risk factors to BMD depends on estrogen receptor α (ERα) gene polymorphisms in Japanese female athletes. Materials and Methods: This study included 280 collegiate female athletes from 12 competitive sports (age, 19.2 ± 1.3 years). Data on sports participation, age at menarche, menstrual cycles, prior stress fractures, and prior eating disorders were obtained through a questionnaire-type survey. Sports types were classified into endurance, esthetic, aquatic, ball, and high load in consideration of exercise load characteristics. ERα gene PvuII (rs2234693) and XbaI (rs9340799) polymorphisms were analyzed by TaqMan^® assay. The total body BMD was measured by dual-energy X-ray absorptiometry. Results: On multiple regression analysis, sports types, body mass index (BMI), menarche, and XbaI polymorphism remained robust independent predictors of BMD. However, prior stress fractures and menstrual cycles were excluded. In athletes carrying the XX+Xx genotype of XbaI polymorphism, sports types and BMI were associated with BMD. However, in athletes carrying the xx genotype of XbaI polymorphism, sports types, BMI, and menarche were associated with BMD. These results indicated that athletes carrying the xx genotype with delayed menarche had low BMD. Conclusions: In collegiate female athletes, participation in endurance, esthetic, and aquatic sports types and a low BMI are associated with low BMD. In addition, delayed menarche may negatively affect BMD in athletes carrying the xx type of ERα gene XbaI polymorphism.

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.

Prevalence of osteoporosis and vitamin D receptor gene polymorphisms (FokI) in an Iranian general population based study (Kurdistan) (IMOS)

BACKGROUND

Osteoporosis, or porous bone, is a disease characterized by low bone mass density (BMD) and structural deterioration of bone tissue, leading to bone fragility and increased risk of hip, spine, and wrist fractures. There are numerous risk factors for osteoporosis. While many of these factors are non-genetic in nature, there is a definite genetic component responsible for this condition. The main aim of this study was to evaluate the association between VDR (Vitamin D receptor gene) polymorphisms (Fok1) A>G (rs2228570) and bone mineral density in an Iranian defined population.

METHODS

The study participants comprised of 1032 Iranians recruited from the city of Sanandaj during IMOS (Iranian Multi Center Osteoporosis Study). Bone mineral density measurement was performed in all the participants with and without osteoporosis. All samples were genotyped for VDR genes (Fok1) polymorphism with polymerase chain reaction, using a predesigned TaqMan allele discrimination assay.

RESULTS

There was a significant association between Fok1 polymorphism and osteoporosis in postmenopausal women, 0.138 (0.025-0.768).

CONCLUSION

It seems that cohort studies, which are more powerful than case-control studies, can be useful in evaluating the roles of genetic variants as risk or protective factors for osteoporosis.

Chronic administration of anticonvulsants but not antidepressants impairs bone strength: clinical implications

Major depression and bipolar disorder are associated with decreased bone mineral density (BMD). Antidepressants such as imipramine (IMIP) and specific serotonin reuptake inhibitors (SSRIs) have been implicated in reduced BMD and/or fracture in older depressed patients. Moreover, anticonvulsants such as valproate (VAL) and carbamazepine (CBZ) are also known to increase fracture rates. Although BMD is a predictor of susceptibility to fracture, bone strength is a more sensitive predictor. We measured mechanical and geometrical properties of bone in 68 male Sprague Dawley rats on IMIP, fluoxetine (FLX), VAL, CBZ, CBZ vehicle and saline (SAL), given intraperitoneally daily for 8 weeks. Distinct regions were tested to failure by four-point bending, whereas load displacement was used to determine stiffness. The left femurs were scanned in a MicroCT system to calculate mid-diaphyseal moments of inertia. None of these parameters were affected by antidepressants. However, VAL resulted in a significant decrease in stiffness and a reduction in yield, and CBZ induced a decrease in stiffness. Only CBZ induced alterations in mechanical properties that were accompanied by significant geometrical changes. These data reveal that chronic antidepressant treatment does not reduce bone strength, in contrast to chronic anticonvulsant treatment. Thus, decreased BMD and increased fracture rates in older patients on antidepressants are more likely to represent factors intrinsic to depression that weaken bone rather than antidepressants per se. Patients with affective illness on anticonvulsants may be at particularly high risk for fracture, especially as they grow older, as bone strength falls progressively with age.

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.

Genetic and environmental factors in human osteoporosis

Osteoporosis is a common disorder, with prolongation of the average life span it has become a major public health problem. On the formation of osteoporosis genetic factors and environmental influences could play a role then it is considered as multi-factorial. Because a variety of functions to affect susceptibility to the formation of osteoporosis VDR-F, VDR-B, COL1A1, ESR1X, ESR1P and CTR are thought to be candidate genes. In this study, the aim is to investigate the relationship between these genes polymorphism and bone mineral density (BMD) values of lumbar vertebra and femoral neck in 188 Turkish people. Lumbar spine and femoral neck BMD of the individuals included in the study were measured by the dual X-ray absorptiometry method. The genotyped polymorphisms by simultaneous amplification of five regions of the genome, containing six SNPs of interest and detecting the amplified product, using the kit MetaBone Clinical Arrays(®). Statistical analyses indicated that; VDR-B gene polymorphisms major (P = 0.013), VDR-F polymorphisms have minor (P = 0.082) effect on femur BMD. None of the other genes has any significant effect on spinal BMD. Patient age, body mass index and diet has significant effect on femoral and spinal BMD. Osteoporosis is a multi-factorial disease and many genetic and non-genetic risk factors contribute to the development of osteoporosis. Early detection of a genetic predisposition to osteoporosis should allow delay and/or limit unfavorable changes in the bone tissue.

Adverse effects of corticosteroids on bone metabolism: a review

Glucocorticoid (GC) exposure is the most common etiology of drug-induced (secondary) osteoporosis. Twenty percent of all cases of osteoporosis have been attributed to GC exposure. Significant risk factors for the development of fractures after GC exposure include age older than 65 years, prolonged GC exposure (>3 months), positive family history of osteoporosis, and low calcium intake. GCs are known to inhibit bone remodeling and to increase fracture risk. GC exposure alters the fragile balance between osteoclast and osteoblast activity in bone metabolism. GC stimulates osteoclast-mediated bone resorption and reduces osteoblast-mediated bone formation, which results in increased overall net bone resorption. Specifically, the 2 main effects of GCs on bone metabolism are (1) inducing apoptosis in osteoblasts and osteocytes, thereby decreasing bone formation, and (2) prolonging the lifespan of osteoclasts and increasing bone resorption. The risk of fracture decreases 3 months after cessation of GC therapy; thus, a 3-month period may be ideal between GC exposures in patients at high risk for the development of osteoporosis. Patients managed with GCs who are at high risk for the development of secondary osteoporosis should have appropriate diagnostic testing; pre-GC exposure medication management (ie, use of bisphosphonates, human parathyroid hormone); and a limitation of GC therapy, with a wait period of 3 months between GC exposures if possible.

Risk factors for osteoporosis after renal transplantation and effect of vitamin D receptor Bsm I polymorphism

OBJECTIVE

Rapid loss of vertebral or hip mineral density after renal transplantation is a major complication which occurs within 6-12 months. The aim of this study was to evaluate risk factors contributing to bone disease in the early stage after renal transplantation and the effect of vitamin D receptor (VDR) gene polymorphisms.

METHODS

We prospectively followed for up to 12 months 44 patients (29 men and 15 women) with end-stage renal disease who underwent kidney transplantation. All patients received prednisone with either cyclosporine (CsA)/mycophenolate mofetil (MMF) or tacrolimus (Tac)/MMF therapy. Spine, hip, and whole body bone mineral density (BMD) was measured at 12 months after transplantation. According to World Health Organization recommendations, our patients were categorized as normal, osteopenic, or osteoporotic BMD levels. VDR alleles were genotyped as BB, Bb, or bb by polymerase chain reactions based on polymorphism at the Bsm I restriction site.

RESULTS

Forty-six percent of patients were normal, 43% osteopenic, and 11% osteoporotic. Significant risk factors for osteoporosis among renal transplant recipients were younger age and pretransplant high intact parathyroid hormone (iPTH) levels. (P values .045 and .027, respectively). According to polymorphic group categorization, posttransplant serum Ca was significantly higher in patients with BB or Bb genotype than in those with bb genotype (P = .012). Although there was no statistical significance regarding iPTH levels, it was higher among Bb+BB than the bb genotype group. Also, first-year BMD analysis after transplantation according to Bsm I polymorphism showed significant differences in femur BMD levels according to the dual classification of polymorphism (P < .05). The BMD levels in the bb group was higher than in the Bb+BB group.

CONCLUSIONS

Although high pretransplant iPTH levels and younger age enhanced posttransplant bone loss, functionally different alleles of the VDR gene may modulate bone turnover during the first year after renal transplantation.

The relationship between vitamin D receptor gene polymorphisms and bone density, osteocalcin level and growth in adolescents

BACKGROUND/OBJECTIVE

The relationship between vitamin D receptor gene polymorphisms and bone density, osteocalcin and growth was investigated.

SUBJECTS

Eighty eight adolescents aged between 8-15, with no history of illness influencing the level of bone parameters, were examined in our study.

METHODS

Areal BMD for lumbar spine (L1-4) was assessed by dual energy X-ray absorptiometry (DEXA). Height and weight were measured on the day of the DEXA scans. Serum osteocalcin level was determined by using ELISA method. DNA was extracted from white blood cells, amplified by the polymerase chain reaction (PCR) and the polymorphic sites were analyzed by using ApaI, TaqI and FokI restriction enzymes.

RESULTS

The most frequent genotypes were FF (% 54.6), Aa (% 53.4) and Tt (% 48.8). No significant relationship was found between VDR genotypes and areal BMD, osteocalcin level or growth in either sex. But there was a strong tendency for a higher BMD at the lumbar spine of TT and AA genotypes compared to tt and Aa genotypes. The children with TT genotype were taller and heavier than the children with tt genotype

CONCLUSION

Our results suggest that VDR gene TaqI polymorphism may be associated with body weight and bone mass, but more studies with larger groups should be conducted.

Genome-wide association study of bone mineral density in premenopausal European-American women and replication in African-American women

CONTEXT

Several genome-wide association studies (GWAS) have been performed to identify genes contributing to bone mineral density (BMD), typically in samples of elderly women and men.

OBJECTIVE

The objective of the study was to identify genes contributing to BMD in premenopausal women.

DESIGN

GWAS using the Illumina 610Quad array in premenopausal European-American (EA) women and replication of the top 50 single-nucleotide polymorphisms (SNPs) for two BMD measures in African-American (AA) women.

SUBJECTS

Subjects included 1524 premenopausal EA women aged 20-45 yr from 762 sibships and 669 AA premenopausal women aged 20-44 yr from 383 sibships.

INTERVENTIONS

There were no interventions.

MAIN OUTCOME MEASURES

BMD was measured at the lumbar spine and femoral neck by dual-energy x-ray absorptiometry. Age- and weight-adjusted BMD values were tested for association with each SNP, with P values determined by permutation.

RESULTS

SNPs in CATSPERB on chromosome 14 provided evidence of association with femoral neck BMD (rs1298989, P = 2.7 x 10(-5); rs1285635, P = 3.0 x 10(-5)) in the EA women, and some supporting evidence was also observed with these SNPs in the AA women (rs1285635, P = 0.003). Genes identified in other BMD GWAS studies, including IBSP and ADAMTS18, were also among the most significant findings in our GWAS.

CONCLUSIONS

Evidence of association to several novel loci was detected in a GWAS of premenopausal EA women, and SNPs in one of these loci also provided supporting evidence in a sample of AA women.

Effect of age, gender and calciotropic hormones on the relationship between vitamin D receptor gene polymorphisms and bone mineral density

BACKGROUND/OBJECTIVES

Hypovitaminosis D is a major public health problem worldwide and unexpectedly more so in sunny countries. Vitamin D receptor (VDR) gene is associated with inter-individual variance in bone mineral density (BMD). Studies assessing the effect of VDR gene polymorphisms on BMD yielded conflicting results. The aim of this study was to assess the relationship between VDR polymorphisms and BMD in the Lebanese, across age groups and genders and to assess the effect of PTH and lean mass and vitamin D levels on such relationship.

SUBJECTS/METHODS

In total, 203 subjects aged 65-85 years and 336 children aged 10-17 years. Polymorphisms in the VDR gene were assessed with the restriction enzymes BsmI, TaqI and ApaI. Bone mineral content, BMD and lean mass were measured using Dual-Energy X-ray Absorptiometry (DXA). The dominant hand strength was measured in children.

RESULTS

Heterozygote genotype was the most frequent in both age groups. There was no difference in the frequency distribution of genotypes between the young and the elderly. No relationship between VDR genotypes and lean mass was found in either age group. Heterozygote boys had the lowest parathormone (PTH) and heterozygote elderly women had the highest BMD at the spine and forearm.

CONCLUSIONS

In the Lebanese, the relationship between VDR polymorphisms and BMD differs by age. Survival does not seem to differ by VDR genotype. However, further studies are needed to assess the effect of VDR gene polymorphisms on mortality per se and time to mortality, not evaluated in this study.

Current evidence for a modulation of low back pain by human genetic variants

The manifestation of chronic back pain depends on structural, psychosocial, occupational and genetic influences. Heritability estimates for back pain range from 30% to 45%. Genetic influences are caused by genes affecting intervertebral disc degeneration or the immune response and genes involved in pain perception, signalling and psychological processing. This inter-individual variability which is partly due to genetic differences would require an individualized pain management to prevent the transition from acute to chronic back pain or improve the outcome. The genetic profile may help to define patients at high risk for chronic pain. We summarize genetic factors that (i) impact on intervertebral disc stability, namely Collagen IX, COL9A3, COL11A1, COL11A2, COL1A1, aggrecan (AGAN), cartilage intermediate layer protein, vitamin D receptor, metalloproteinsase-3 (MMP3), MMP9, and thrombospondin-2, (ii) modify inflammation, namely interleukin-1 (IL-1) locus genes and IL-6 and (iii) and pain signalling namely guanine triphosphate (GTP) cyclohydrolase 1, catechol-O-methyltransferase, mu opioid receptor (OPMR1), melanocortin 1 receptor (MC1R), transient receptor potential channel A1 and fatty acid amide hydrolase and analgesic drug metabolism (cytochrome P450 [CYP]2D6, CYP2C9).

Association of adenylate cyclase 10 (ADCY10) polymorphisms and bone mineral density in healthy adults

Phenotypic variation in bone mineral density (BMD) among healthy adults is influenced by both genetic and environmental factors. Sequence variations in the adenylate cyclase 10 (ADCY10) gene, which is also called soluble adenylate cyclase, have previously been associated with low spinal BMD in hypercalciuric patients. Since ADCY10 is located in the region linked to spinal BMD in our previous linkage analysis, we tested whether polymorphisms in this gene are also associated with normal BMD variation in healthy adults. Sixteen single-nucleotide polymorphisms (SNPs) distributed throughout ADCY10 were genotyped in two healthy groups of American whites: 1692 premenopausal women and 715 men. Statistical analyses were performed in the two groups to test for association between these SNPs and the femoral neck and lumbar spine areal BMD. We observed significant evidence of association (p < 0.01), with one SNP each in men and women. Genotypes at these SNPs accounted for <1% of hip BMD variation in men but 1.5% of spinal BMD in women. However, adjacent SNPs did not corroborate the association in either men or women. In conclusion, we found a modest association between an ADCY10 polymorphism and the spinal areal BMD in premenopausal white women.

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.

Identification of a linkage disequilibrium block in chromosome 1q associated with BMD in premenopausal white women

Osteoporosis is a complex disease with both genetic and environmental risk factors. A major determinant of osteoporotic fractures is peak BMD obtained during young adulthood. We previously reported linkage of chromosome 1q (LOD = 4.3) with variation in spinal areal BMD in healthy premenopausal white women. In this study, we used a two-stage genotyping approach to identify genes in the linked region that contributed to the variation of femoral neck and lumbar spine areal BMD. In the first stage, 654 SNPs across the linked region were genotyped in a sample of 1309 premenopausal white women. The most significant evidence of association for lumbar spine (p = 1.3 x 10(-6)) was found with rs1127091 in the GATAD2B gene. In the second stage, 52 SNPs around this candidate gene were genotyped in an expanded sample of 1692 white women. Significant evidence of association with spinal BMD (p < 10(-5)), and to a lesser extent with femoral neck BMD, was observed with eight SNPs within a single 230-kb linkage disequilibrium (LD) block. The most significant SNP (p = 3.4 x 10(-7)) accounted for >2.5% of the variation in spinal BMD in these women. The 230-kb LD block contains 11 genes, but because of the extensive LD, the specific gene(s) contributing to the variation in BMD could not be determined. In conclusion, the significant association between spinal BMD and SNPs in the 230-kb LD block in chromosome 1q indicates that genetic factor(s) in this block plays an important role in peak spinal BMD in healthy premenopausal white women.

Association studies of ALOX5 and bone mineral density in healthy adults

Animal studies suggest that arachidonate 5-lipoxygenase (encoded by ALOX5) may be a genetic determinant of bone mineral density. We tested this hypothesis in a sample of healthy men and women and did not find consistent evidence for an association between variation in this gene and either lumbar spine or femoral neck BMD.

INTRODUCTION

Phenotypic variation in bone mineral density (BMD) among healthy adults is influenced by both genetic and environmental factors. A recent mouse study implicated ALOX5, which encodes arachidonate 5-lipoxygenase, as a contributing factor to areal BMD (aBMD).

METHODS

Fifteen single nucleotide polymorphisms (SNPs) distributed throughout ALOX5 were genotyped in three healthy groups: 1,688 European American, premenopausal sisters, 512 African American premenopausal sisters and 715 European American brothers. Statistical analyses were performed in the three groups to test for association between these SNPs and femoral neck and lumbar spine aBMD.

RESULTS

Significant (p < or = 0.05) evidence of association was observed with three of the SNPs. However, despite the linkage disequilibrium between SNPs, adjacent SNPs did not provide statistical evidence of association in any of the three study groups.

CONCLUSIONS

These data do not provide consistent evidence of association between genomic variation in ALOX5 and clinical variability in aBMD in healthy subjects.

Bone mass and breast milk calcium concentration are associated with vitamin D receptor gene polymorphisms in adolescent mothers

Lactation-associated bone loss has been reported in adolescent mothers. Polymorphisms in the vitamin D receptor (VDR) gene may contribute to differences in the physiologic skeletal response to lactation in these mothers. We evaluated the influence of VDR gene polymorphisms ApaI, BsmI, and TaqI on bone mass, bone and calcium-related hormones, and breast milk calcium of lactating adolescents with habitually low calcium intake. Total body bone mineral content (TBMC), total body bone mineral density (TBMD), lumbar spine BMD (LSBMD), serum hormones [intact parathyroid hormone (iPTH), 25-hydroxyvitamin D, insulin-like growth factor-I (IGF1), prolactin, and estradiol), and breast milk calcium were measured in 40 lactating Brazilian adolescents (15-18 y), and compared by VDR genotype subgroups after adjustment for calcium intake and postmenarcheal and lactational periods. TBMD and LSBMD Z scores were -0.55 +/- 1.01 and -1.15 +/- 1.48, respectively. LSBMD was higher (21%; P < 0.05) in adolescents with the aa genotype (n = 5) compared with those with the AA genotype (n = 7). TBMC and IGF1 were higher (23 and 50%, respectively; P < 0.05) in adolescents with tt (n = 4) than those with TT (n = 29) and Tt (n = 7) genotypes. Breast milk calcium and serum iPTH were higher (24 and 80%, respectively; P < 0.05) in adolescents with bb (n = 8) compared with those with BB (n = 21) genotype. These results indicate that bone mass and breast milk calcium are significantly associated with VDR genotypes in lactating Brazilian adolescents. Those with aa and tt genotypes had a better bone status and those with bb genotype had greater breast milk calcium.

Genetic susceptibility to total hip arthroplasty failure: a preliminary study on the influence of matrix metalloproteinase 1, interleukin 6 polymorphisms and vitamin D receptor

BACKGROUND

Matrix metalloproteinase (MMP)1, interleukin(IL)6 and vitamin D receptor (VDR) have been implicated in the biological cascade of events initiated by particulate wear debris and bacterial infection, resulting in periprosthetic bone loss around loosened total hip replacements (THRs). The individual responses to such stimuli may be dictated by genetic variation.

OBJECTIVE

To study the effect of single-nucleotide polymorphisms (SNPs) within these candidate genes.

METHODS

A case-control study of the MMP1, IL6 and VDR genes was performed for possible association with deep sepsis or aseptic loosening. All cases included in the study were Caucasian patients with osteoarthritis who had received a cemented Charnley total hip arthroplasty (THA) and polyethylene acetabular cup. Cases consisted of 91 patients with early aseptic loosening and 71 patients with microbiological evidence of deep infection on surgery. Controls consisted of 150 patients with THAs that were clinically asymptomatic for over 10 years and showed no radiographic features of aseptic loosening. DNA samples from all individuals were genotyped using Taqman allelic discrimination.

RESULTS

The C allele (p = 0.001; OR = 3.27; 95% CI 2.21 to 4.83) and C/C genotype (p = 0.001) for the MMP1 SNP were highly associated with aseptic failure when compared with controls. No statistically significant relationships were found between aseptic loosening and the MMP2, MMP4, IL6 -174 or VDRL SNPs. The T allele (p = 0.007; OR = 1.76; 95% CI 1.16 to 2.66) and T/T genotype (p = 0.028) for VDR-T were statistically associated with osteolysis owing to deep infection as compared with controls. No statistically significant relationship was found between septic failure and any of the other SNPs examined in this study.

CONCLUSIONS

Aseptic loosening and possibly deep infection of THR may be due to the genetic influence of candidate susceptibility genes. SNP markers may serve as predictors of implant survival and aid in pharmacogenomic prevention of THR failure.

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

Associations of the FokI, BsmI, ApaI, and TaqI polymorphisms of the vitamin D receptor (VDR) gene with the bone mineral density (BMD) of the lumbar part of the spinal column (BMD LS) and the neck of the femur (BMD FN), and with the occurrence of fractures, were studied using the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis on DNA isolated from peripheral blood of 239 women and 40 men from the region of western Poland. Three polymorphisms of the 3' end of the VDR gene (BsmI, ApaI, TaqI) indicated a strong linkage disequilibrium. Association analysis of the VDR gene FokI polymorphism with BMD LS showed a dose effect of allele f. The association of the bAT haplotype of the BsmI, ApaI, and TaqI polymorphisms of the VDR gene with BMD FN was statistically significant. The association of the ApaI polymorphism with the occurrence of fractures was observed. Associations were also observed between the occurrence of fractures and the baT haplotypes of the VDR gene.

Vitamin D receptor polymorphisms and diseases

The vitamin D endocrine system is central to the control of bone and calcium homeostasis. Thus, alterations in the vitamin D pathway lead to disturbances in mineral metabolism. Furthermore, a role for vitamin D has been suggested in other diseases, like cancer, diabetes and cardiovascular disease. Expression and nuclear activation of the vitamin D receptor (VDR) are necessary for the effects of vitamin D. Several genetic variations have been identified in the VDR. DNA sequence variations, which occur frequently in the population, are referred to as "polymorphisms" and can have biological effects. To test whether there is a linkage between VDR polymorphisms and diseases, epidemiological studies are performed. In these studies, the presence of a variation of the gene is studied in a population of patients, and then compared to a control group. Thus, association studies are performed, and a link among gene polymorphisms and diseases can be established. Since the discovery of VDR polymorphisms a number of papers have been published studying its role in bone biology, renal diseases, diabetes, etc. The purpose of this review is to summarize the vast amount of information regarding vitamin D receptor polymorphisms and human diseases, and discuss its possible role as diagnostic tools.

Human ALOX12, but not ALOX15, is associated with BMD in white men and women

The Alox15 gene was recently identified as a negative regulator of peak BMD in mice. Polymorphisms in human ALOX12, but not ALOX15, were significantly associated with spine BMD in white men and women, suggesting that ALOX12 may contribute to normal variation in BMD.

INTRODUCTION

Osteoporosis is a complex disease with both genetic and environmental risk factors. A major determinant of osteoporosis is peak BMD, which is a highly heritable trait. Recently, the arachidonate 15-lipoxygenase (Alox15) gene was identified as a negative regulator of peak BMD in mice.

MATERIALS AND METHODS

To assess the contribution of lipoxygenase genes to normal BMD variation in healthy white men and women, we performed population- and family-based association studies of two arachidonate lipoxygenase genes: ALOX15, which is the human homolog of mouse Alox15, and ALOX12, which is functionally similar to Alox15. Single nucleotide polymorphisms (SNPs) distributed across the two genes were genotyped. BMD was measured at the femoral neck and lumbar spine in 411 men 18-61 years of age and 1291 premenopausal women 20-50 years of age.

RESULTS

Moderate evidence of association was found between spine BMD and six SNPs in the ALOX12 gene in both men and women (p = 0.0052-0.050). Furthermore, the most common SNP haplotype in ALOX12 showed evidence of significant association with high spine BMD in men (p = 0.0083), whereas the second most common haplotype was associated with high spine BMD in women (p = 0.0081).

CONCLUSIONS

Polymorphisms in the ALOX12 gene may contribute to normal variation in spine BMD.

Influence of IL-6, COL1A1, and VDR gene polymorphisms on bone mineral density in Crohn's disease

BACKGROUND

Osteoporosis is an important cause of morbidity in patients with Crohn's disease. The pathogenesis of reduced bone mineral density (BMD) is multifactorial. A range of genetic factors have been implicated in other populations of patients with osteoporosis.

AIM

To investigate the influence of interleukin 6 (IL-6), collagen type 1alpha1 (COL1A1), and vitamin D receptor gene (VDR) single nucleotide polymorphisms (SNP) on BMD in patients with Crohn's disease.

PATIENTS

A cohort of 245 well characterised patients with Crohn's disease were recruited from the inflammatory bowel disease register at the Freeman Hospital and Royal Victoria Infirmary, Newcastle upon Tyne, and the Queen Elizabeth Hospital, Gateshead, UK.

METHODS

Patients were genotyped for IL-6 C-174G SNP, COL1A1 Sp1 binding site G T SNP, VDR Taq1, and Fok1 SNPs, and CARD15 R702W, G908R, and L1007fs SNPs. BMD was measured at the lumbar spine (LSP) and hip using dual energy x ray absorptiometry.

RESULTS

A total of 158 female and 87 male patients, aged 24-70 years (mean 44), were recruited. There were no significant differences in the distribution of the tested SNPs when analysed for age, body mass index, pre/post-menopausal status, smoking, or steroid use. Two hundred and thirteen patients were genotyped for the IL-6 SNP. LSP and total hip BMD was significantly lower in patients with the GG genotype (48%) than the CC genotype (15%) (p = 0.041, p = 0.014). One hundred and eighty patients were genotyped for the COL1A1 SNP. There was no significant difference in BMD at LSP. Hip BMD was significantly lower in heterozygous patients compared with homozygous wild-types (p = 0.034). There were no significant differences in BMD between genotypes for the two VDR SNPs or the CARD15 genotypes examined.

CONCLUSION

IL-6 and COL1A1 gene polymorphisms influence BMD in patients with Crohn's disease but the particular VDR gene polymorphisms studied do not have a major effect.

Bone mineral density, body height, and vitamin D receptor gene polymorphism in middle-aged men

BACKGROUND

Polymorphisms of the vitamin D receptor (VDR) gene have been suggested to account for some of the genetic variation in bone mass. However, the relationship has been controversial. It has been suggested that environmental factors such as physical activity may be one of the many reasons for this controversy.AIM. We investigated the possible interactions of VDR gene polymorphisms and low to moderate intensity exercise on bone mineral density (BMD) in a four-year controlled, randomized intervention trial in 140 middle-aged Finnish men.

METHOD

The TaqI, FokI, and ApaI restriction fragment length polymorphism (RFLP)-markers of the VDR gene were evaluated. BMDs of the lumbar spine (L2-L4), femoral neck, and total proximal femur were measured with dual-energy X-ray absorptiometry (DXA). In addition, the relations of the VDR gene polymorphism with bone turnover markers (serum tartrate-resistant acid phosphatase (TRAP) 5b activity and serum osteocalcin concentration) were evaluated.

RESULTS

At the randomization, the subjects with the VDR TaqI Tt or tt genotype had a greater body height than the subjects with TT genotype (P=0.001). In addition, the association of VDR TaqI polymorphism with femoral BMD was found. The Tt or tt genotype associated with higher femoral neck values than the TT genotype (P=0.003) at randomization. After adjusting the femoral neck for body height, the association remained (P=0.021). We did not find any association between VDR gene polymorphism and bone turnover markers or any interactions of VDR gene polymorphisms and exercise on BMD.

CONCLUSIONS

The TaqI polymorphism may be associated with body height and femoral neck BMD values. The present findings also suggest that the VDR polymorphisms do not modify the effect of regular aerobic exercise on BMD. However, more randomized controlled exercise trials are needed to investigate the role of exercise intensity on VDR gene polymorphisms, and the role of VDR gene polymorphisms on BMD.

Heritability of spinal trabecular volumetric bone mineral density measured by QCT in the Diabetes Heart Study

The heritability of trabecular volumetric bone mineral density (BMD) determined by quantitative computed tomography (QCT) has not yet been reported. The purpose of this study was to investigate the heritability of BMD as determined by QCT and DXA in 124 women and 120 men (age 39-83 years, BMI 17-75, 84% type 2 diabetics) from 101 families (232 sibling pairs) in the Diabetes Heart Study. Volumetric BMD had a heritability (h2) estimate of 0.73 (SE = 0.15, P < 0.0001) at the lumbar spine and 0.71 (SE = 0.15, P < 0.0001) at the thoracic spine. Areal BMD heritability estimates were 0.56 for PA spine, 0.43 for total hip, 0.43 for femoral neck, 0.45 for distal radius, 0.42 for mid-radius, and 0.52 for whole body (all P < 0.01). After accounting for familial correlation using generalized estimating equations, volumetric BMD was inversely associated with age (r = -0.52, P < 0.0001) and duration of diabetes (r = -0.24, P < 0.01) and positively associated with body weight (r = 0.25, P < 0.01). In multivariate analysis, adjustment for age, sex, and race lowered the h2 estimates for volumetric BMD at the lumbar (h2 = 0.41, P < 0.01) and thoracic (h2 = 0.48, P < 0.001) spine, increased the h2 estimate for areal BMD at the mid radius (h2 = 0.58, P < 0.0001), and had little effect on the h2 estimate for areal BMD at other sites (h2 = 0.41-0.55, all P < 0.01). Additional adjustment for BMI, duration of diabetes, and physical activity had little effect on the h2 estimates for volumetric BMD or areal BMD except at the hip where they were lowered (h2 = 0.31-0.33, all P < 0.05). These data suggest that, like areal BMD, volumetric BMD is highly heritable and may be used in designing linkage studies to locate genes governing bone metabolism.

Autosomal dominant avascular necrosis of femoral head in two Taiwanese pedigrees and linkage to chromosome 12q13

Avascular necrosis of the femoral head (ANFH) is a debilitating disease that commonly leads to destruction of the hip joint in adults. The etiology of ANFH is unknown, but previous studies have indicated that heritable thrombophilia (increased tendency to form thrombi) and hypofibrinolysis (reduced ability to lyse thrombi), alcohol intake, and steroid use are risk factors for ANFH. We recently identified two families with ANFH showing autosomal dominant inheritance. By applying linkage analysis to a four-generation pedigree, we excluded linkage between the family and three genes related to thrombophilia and hypofibrinolysis: protein C, protein S, and plasminogen activator inhibitor. Furthermore, by a genomewide scan, a significant two-point LOD score of 3.45 (recombination fraction [theta] = 0) was obtained between the family with ANFH and marker D12S85 on chromosome 12. High-resolution mapping was conducted in a second family with ANFH and replicated the linkage to D12S368 (pedigree I: LOD score 2.47, theta = 0.05; pedigree II: LOD score 2.81, theta = 0.10). When an age-dependent-penetrance model was applied, the combined multipoint LOD score was 6.43 between D12S1663 and D12S85. Thus, we mapped the candidate gene for autosomal dominant ANFH to a 15-cM region between D12S1663 and D12S1632 on chromosome 12q13.

Association of bone mineral density with vitamin D and estrogen receptor gene polymorphisms during GnRH agonist treatment

AIMS

This study examined whether or not a decrease in bone mineral density (BMD) induced by the use of gonadotropin-releasing hormone agonist (GnRHa) during sexual maturation is affected by vitamin D receptor and/or estrogen receptor gene polymorphisms, like the phenomenon observed during the postmenopausal period.

METHODS

In 43 patients who received GnRHa therapy for 6 months to treat uterine myoma or endometriosis at our department and who were confirmed to have pituitary down-regulation, we measured bone density before and after GnRHa treatment using DXA and analyzed the bone metabolism turnover using bone metabolic markers. Polymorphisms were analyzed by RFLP using FokI and TaqI for the vitamin D receptor gene and PvuII and XbaI for the estrogen receptor gene. The then determined gene polymorphism was analyzed in relation to the percentage decreases in BMD following GnRHa treatment.

RESULTS

The patients were divided by f, t into two groups: (f, t) < 2 (Group V-I) and (f, t) > or = 2 (Group V-II). They were also divided by P, x into two groups (P, x) < 3 (Group E-I) and (P, x) > or = 3 (Group E-II). The BMD change was significantly higher in Group V-II than in Group V-I. Group E-II tended to have a higher BMD change than Group E-I, although this difference was not statistically significant.

CONCLUSION

Patients who often have f and t polymorphism are more likely to show BMD reduction following GnRHa therapy, like the phenomenon seen during the postmenopausal period, than patients with other gene polymorphisms. Measures to avoid BMD reduction are required when using GnRHa in such patients.

Bone density in sheep: genetic variation and quantitative trait loci localisation

Bone density (BD) is an important factor in osteoporotic fracture risk in humans. However, BD is a complex trait confounded by environmental influences and polygenic inheritance. Sheep provide a potentially useful model for studying differences in BD, as they provide a means of circumventing complex environmental factors and are a similar weight to humans. The aims of this study were to establish whether there is genetic variation in BD in sheep and then to localise quantitative trait loci (QTLs) associated with this variation. We also aimed to evaluate the relationship between fat and muscle body components and BD in sheep. Results showed that there was significant (P < 0.01) genetic variation among Coopworth sheep sires for BD. This genetic difference was correlated (P < 0.01) with body weight and muscle mass. A number of QTLs exceeding the suggestive threshold were identified (nine in total). Of these, two (chromosomes 1, P < 0.05; chromosome 24, P < 0.01) were significant using genome-wide permutation significance thresholds (2000 iterations). The position of the QTL on chromosome 24 coincided with a number of other body composition QTLs, indicating possible pleiotropic effects or the presence of multiple genes affecting body composition at that site. This study shows that sheep are potentially a useful model for studying the genetics of BD.

Association of vitamin D receptor gene polymorphisms with bone mineral density in postmenopausal women of Hellenic origin

OBJECTIVES

There are numerous indications that genetic factors play an important role in the pathogenesis of osteoporosis, a common condition characterized by reduced bone mass and increased fracture risk. The vitamin D receptor (VDR) gene has been suggested as a possible candidate gene for the regulation of bone mass but the relationship between VDR polymorphisms and bone mineral density (BMD) is controversial and has not been confirmed by all workers in different ethnic groups studied.

METHODS

In order to evaluate the contribution of the VDR alleles in bone mass loss, the BsmI, ApaI and TaqI polymorphisms in the VDR gene were studied in 126 postmenopausal women.

RESULTS

It was found that the bb, aa and TT genotypes and the bAT and baT haplotypes were associated with a lower BMD measured at the forearm.

CONCLUSIONS

Our analysis reveals a significant association between VDR gene alleles and bone mass in the population studied.

Influence of polymorphisms in VDR and COLIA1 genes on the risk of osteoporotic fractures in aged men

BACKGROUND

Osteoporosis in chronic renal failure is a common finding caused by several factors, including age. In the last decade, the likely effect of genetic markers related with the appearance and evolution of osteoporosis has been mainly studied in women, with no categorical results. The aim of this study was to assess the influence of polymorphisms of the vitamin D receptor (VDR) and COLIA1 genes on the risk of osteoporotic fractures in men older than 50 years.

METHODS

The study population comprised 156 men, aged 64 +/- 9 (50-86), randomly selected from the population list of Oviedo, Spain. Prevalent vertebral fractures and incident non-vertebral fractures were identified, as well as several genetic polymorphisms. Prevalent vertebral fractures were considered according to the Genant grade 2 classifications. The analyzed genetic polymorphisms were located on restriction sites BsmI (B,b), ApaI (A,a), and TaqI (T,t) in the VDR and on Sp1 (S,s) in COLIA1.

RESULTS

Although none of the VDR gene polymorphisms separately analyzed showed any differences between fractured and non-fractured men, the utilization of haplotypes could be employed in order to find osteoporotic fractures in men. By contrast, the COLIA1 polymorphism was associated with osteoporotic fractures. The percentage of prevalent vertebral fractures was significantly higher in the "ss" genotype with respect to the other genotypes. These results show that in men, the "ss" genotype of COLIA1 polymorphism could be the best osteoporotic fracture risk genetic predictor, independent of bone mass values.

Do the COL1A1 and Taq 1 vitamin D receptor polymorphisms have a role in identifying individuals at risk of developing osteoporosis?

The distribution of the Taq 1 polymorphism in the vitamin D receptor (VDR) gene and the MSc 1 polymorphism in the collagen 1 alpha 1 (COL1A1) gene were studied in 266 female and 55 male patients attending an osteoporosis clinic. Allele frequency in control (T- or Z-score >-1.0) and osteoporotic (T- or Z-scores <-2.5) groups were compared using Chi squared tests. No differences were found between the 2 groups with either of the polymorphisms. When allele frequency was compared in patients with and without history of fracture, no differences were found in the frequency of the COL1A1 alleles. However there were significantly more fracture patients, who had been previously treated with corticosteroids for other conditions, carrying the T allele of the VDR polymorphism (X2 = 5.65, p>0.01<0.02). In conclusion, neither of these polymorphisms aid in the prediction of osteoporosis but the VDRT allele may carry an increased fracture risk in patients who require corticosteroid treatment.

Tail suspension induces bone loss in skeletally mature mice in the C57BL/6J strain but not in the C3H/HeJ strain

We assessed the effects of tail-suspension in two skeletal genetic backgrounds, the high C3H/HeJ (C3H) and low C57BL/6J (B6) bone masses inbred mice (male, 4-months old). Cancellous bone mass and structural parameters were evaluated in distal femoral metaphysis by three dimensional microcomputed tomography. Bone cellular activities were evaluated by histomorphometry and measurements of alkaline phosphatase activity (ALP) and osteocalcin in blood and deoxypyridinoline (D-pyr) in urine. In C3H mice, 2- and 3-week unloading experiments were performed. After an early and transient decrease in body weight, a 2-week suspension period resulted in stimulation of both bone formation rate by 45% and active osteoclastic surfaces by 19%. D-pyr did not change, but ALP and osteocalcin levels increased by 18% and 72%, respectively, in 2-week suspended mice, and osteocalcin remained elevated by 30% in the 3-week suspended mice. Such cellular modifications allowed the C3H mice to maintain their initial bone mass and trabecular structural parameters even after a 3-week suspension period. In B6 mice, 1- and 2-week unloading experiments were performed. Tail suspension resulted in decreased body weight during the first days followed by an incomplete recovery during the second week of unloading. The resorption activity was unaffected by any suspension time period, whereas a decrease of 42.5% in bone formation rate and of 21.5% in ALP were seen by the end of the first week of suspension, both values being restored after a 2-week suspension period. At this latter time, trabeculae were thinner, leading to a 24.5% cancellous bone loss. Trabecular number and connectivity, rod-plate index, and degree of anisotropy were not modified. We concluded that C3H mice constituted a unique model in which genetic background overwhelmed the usual effects of reduced biomechanical usage in bone, whereas B6 mice, compared with the standardized rat model, offered an alternative model of bone loss in a mature skeleton.

Klotho gene polymorphisms associated with bone density of aged postmenopausal women

Because mice deficient in klotho gene expression exhibit multiple aging phenotypes including osteopenia, we explored the possibility that the klotho gene may contribute to age-related bone loss in humans by examining the association between klotho gene polymorphisms and bone density in two genetically distinct racial populations: the white and the Japanese. Screening of single-nucleotide polymorphisms (SNPs) in the human klotho gene identified 11 polymorphisms, and three of them were common in both populations. Associations of the common SNPs with bone density were investigated in populations of 1187 white women and of 215 Japanese postmenopausal women. In the white population, one in the promoter region (G-395A, p = 0.001) and one in exon 4 (C1818T, p = 0.010) and their haplotypes (p < 0.0001) were significantly associated with bone density in aged postmenopausal women (> or = 65 years), but not in premenopausal or younger postmenopausal women. These associations were also seen in Japanese postmenopausal women. An electrophoretic mobility shift analysis revealed that the G-A substitution in the promoter region affected DNA-protein interaction in cultured human kidney 293 cells. These results indicate that the klotho gene may be involved in the pathophysiology of bone loss with aging in humans.

Two polymorphisms in the vitamin D receptor gene--association with bone mass and 5-year change in bone mass with or without hormone-replacement therapy in postmenopausal women: the Danish Osteoporosis Prevention Study

The significance of an interrelation between nongenetic factors and genotype effects in the regulation of bone mass is not clear. In this prospective study of 429 healthy early postmenopausal Danish women, we investigated the association between bone mineral density (BMD) and the FokI and BsmI polymorphisms in the vitamin D receptor (VDR) gene. Participants were allocated to either hormone-replacement therapy (HRT) or no treatment by randomization or personal choice. After 5 years, 332 women with unchanged treatment status were available for analyses, 98 of these women were still on HRT. No association with initial BMD or 5-year change in BMD was found for either polymorphism. In women with body mass index (BMI) < 25 (n = 282), the f allele was associated with lower BMD of the hip (p < 0.001) and forearm (p = 0.001), and the b allele was associated with lower spine BMD (p = 0.02). Comparing thin/normal weight women with overweight/ obese women of the same genotype, FF women had similar BMD at all measured sites in contrast to Ff and ff women in whom BMD, as expected, was higher in the overweight/obese women. Similar results were found for the BsmI polymorphism with no difference in BMD between BMI groups in BB women. Segregation into groups according to dietary calcium intake did not reveal any genotype association with BMD. These results provide some evidence of a modifying effect of nongenetic factors, specifically BMI, on the association between VDR genotype and BMD. High BMI may protect against lower BMD seen in association with thef or b alleles. In some genotypes (FF and BB), BMI had relatively little effect on BMD.

Association between a functional interleukin-6 gene polymorphism and peak bone mineral density and postmenopausal bone loss in women: the OFELY study

Genetic factors play an important role in determining bone mass and several genes are involved in this process. Interleukin-6 (IL-6) is a candidate gene for regulation of bone mineral density (BMD) and it has been suggested recently that novel IL-6 -174 G/C allelic variants may be associated with peak BMD in young men and with bone resorption in elderly women. In this study, we assessed the relationships between IL-6 gene polymorphism, peak BMD, rate of postmenopausal BMD loss, and bone turnover in women. BMD was measured by dual-energy X-ray absorptiometry in 255 healthy premenopausal women, aged 31-57 years. BMD loss at the forearm was measured over 4 years in 298 healthy untreated postmenopausal women, 50-88 years (mean 64 years). We also measured levels of serum osteocalcin, bone alkaline phosphatase, and N-propeptide of type I collagen for bone formation and three markers of bone resorption, including urinary and serum C-terminal cross-linking telopeptide of type I collagen and urinary N-terminal telopeptide of type I collagen, in both pre- and postmenopausal women at baseline. In premenopausal women we found a significant association between IL-6 genotypes and BMD at the whole body (analysis of variance [ANOVA], p = 0.03), femoral neck (p = 0.03), trochanter (p = 0.014), Ward's triangle (p = 0.03), and total hip (p = 0.006), with subjects having the CC genotype showing 3%-7% higher BMD levels than their GG counterparts. However, after matching women with CC and GG genotypes for body height the differences decreased (2%-4%), and were no longer significant (p = 0.10-0.23). In postmenopausal women the mean rate of loss at the ultradistal radius was significantly associated with IL-6 genotypes (ANOVA, p = 0.049), with women having the CC genotype showing a significantly greater rate of bone loss (p < 0.05) compared with their GC and GG counterparts. After adjustment for weight changes, the difference in the rate of ultradistal radius bone loss between genotypes decreased and was not significant (p = 0.06 for CC vs. GG). A similar trend was observed for distal radius bone loss (p = 0.10, ANOVA), but not for the middle radius. We found no significant association between genotypes, bone turnover markers in premenopausal women, and either bone turnover or BMD in postmenopausal women. We conclude that this new functional IL-6 polymorphism was weakly associated with level of peak BMD and the rate of forearm trabecular postmenopausal bone loss in this cohort of healthy French women. IL-6 genotypes accounted only for a small proportion of the interindividual variation of both peak BMD and rate of bone loss and were not significant after adjustment for height and changes in body weight, respectively, suggesting that part of the effect may have been due to the differences in body size. Larger long-term studies are necessary to assess adequately the relationships between IL-6 genotype, rate of bone loss, and risk of fracture.

Association of klotho gene polymorphism with bone density and spondylosis of the lumbar spine in postmenopausal women

Based on the fact that the klotho-deficient mouse exhibits multiple aging phenotypes, including osteopenia and subchondral sclerosis of joints, we explored the possibility of whether human klotho gene polymorphism is associated with two major age-related skeletal disorders: osteoporosis and spondylosis. Analysis of the CA repeat sequence downstream of the final exon of the klotho gene identified ten types of alleles in Japanese postmenopausal women (n = 377). We investigated the association of this microsatellite polymorphism with bone density and spondylosis score of the lumbar spine. None of the genotypes was associated with bone density in the overall population (n = 377; 754 alleles) nor in the subpopulation at not more than 10 years after menopause (<or=10 years, n = 131; 262 alleles). However, the type 5 allele was significantly associated with low bone density in aged subpopulations at 10-20 years after menopause (n = 144; 288 alleles, p = 0.035) and >20 years after menopause (n = 102; 204 alleles, p = 0.024). The type 7 allele was associated with high bone density in women more than 20 years after menopause (p = 0.042). The association study with spondylosis of postmenopausal women (n = 221) revealed that another distinct allele, type 8, was significantly associated with low spondylosis score at L-4/5 (p = 0.019) and L-5/S-1 (p = 0.048) levels in the subpopulation equal to or younger than the average age (<or=63 years old, n = 119; 238 alleles), but not in the older subpopulation. These findings indicate that the klotho gene may be a candidate for the genetic regulation of common age-related diseases like osteoporosis and spondylosis, and we provide the first evidence suggesting that this gene may be involved in the etiology of human diseases.

Genetics of osteoporosis

Osteoporosis is a common multifactorial disorder of reduced bone mass. The disorder in its most common form is generalized, affecting the elderly, both sexes, and all racial groups. Multiple environmental factors are involved in the pathogenesis. Genes also play a major role as reflected by heritability of many components of bone strength. Quantitative phenotypes in bone strength in the normal population do not conform to a monogenetic mode of inheritance. The common form of osteoporosis is generally considered to be a polygenic disorder arising from the interaction of common polymorphic alleles at quantitative trait loci, with multiple environmental factors. Finding the susceptibility genes underlying osteoporosis requires identifying specific alleles that coinherit with key heritable phenotypes in bone strength. Because of the close correspondence among mammalian genomes, identification of the genes underlying bone strength in mammals such as the mouse is likely to be of major assistance in human studies. Identification of susceptibility genes for osteoporosis is one of several important approaches toward the long-term goal of understanding the molecular biology of the normal variation in bone strength and how it may be modified to prevent osteoporosis. As with all genetic studies in humans, these scientific advances will need to be made in an environment of legal and ethical safeguards that are acceptable to the general public.

No association of vitamin D receptor gene BsmI polymorphisms with calcium oxalate stone formation

BACKGROUND AND PURPOSE

The formation of urinary stones is reported to be associated with the vitamin D receptor (VDR). As the most frequently seen polymorphism within the VDR gene is BsmI, it has been used as a genetic marker in searching for the cause of urolithiasis. We aimed to evaluate the association between calcium stone disease and the BsmI polymorphisms.

MATERIALS AND METHODS

A control group of 90 healthy people and a group of 124 patients with calcium oxalate stones were examined. The polymorphism was detected using polymerase chain reaction (PCR)-based restriction analysis. A PCR product length was determined to be 580 bp (BB) whereas two fragments of 405 bp and 175 bp were determined to be excisable (bb) by BsmI endonuclease. Associations between calcium stone disease and BsmI polymorphisms were evaluated.

RESULTS AND CONCLUSIONS

The results revealed no significant difference between normal individuals and stone patients (P = 0.891). The allelic distribution of B and b were similar within both the normal group and the stone patients. Therefore, the BsmI polymorphism of the VDR gene at intron 8 is not a suitable genetic marker for urinary stone disease.

Vitamin D receptor initiation codon polymorphism influences genetic susceptibility to type 1 diabetes mellitus in the Japanese population

BACKGROUND

Vitamin D has been shown to exert manifold immunomodulatory effects. Type 1 diabetes mellitus (T1DM) is regarded to be immune-mediated and vitamin D prevents the development of diabetes in the NOD mouse. We studied the association between T1DM and the initiation codon polymorphism in exon 2 of the vitamin D receptor gene in a Japanese population. We also investigated associations between the vitamin D receptor polymorphism and GAD65-antibody (Ab) positivity. We carried out polymerase chain reaction-restriction fragment length polymorphism analysis in 110 Japanese T1DM patients and 250 control subjects. GAD65 antibodies were assessed in 78 patients with T1DM.

RESULTS

We found a significantly higher prevalence of the F allele / the FF genotype in the patients compared to the controls (P = 0.0069 and P = 0.014, respectively). Genotype and allele frequencies differed significantly between GAD65-Ab-positive patients and controls (P = 0.017 and P = 0.012, respectively), but neither between GAD65-Ab-negative patients and controls (P = 0.68 and P = 0.66, respectively) nor between GAD65-Ab-positive and -negative patients (P = 0.19 and P = 0.16, respectively).

CONCLUSIONS

Our findings suggest that the vitamin D receptor initiation codon polymorphism influences genetic susceptibility to T1DM among the Japanese. This polymorphism is also associated with GAD65-Ab-positive T1DM, although the absence of a significant difference between GAD65-Ab-negative patients and controls might be simply due to the small sample size of patients tested for GAD65 antibodies.

Calcium intake and bone mass development among Israeli adolescent girls

OBJECTIVE

To determine the possible relationship between food and life style habits and bone health in adolescent Israeli females.

METHODS

2,000 adolescent Israeli Jewish and Arab high-school girls (mean age 14.5) completed a semi-quantitative food frequency questionnaire and a personal history questionnaire. 27 food components were calculated for each subject. Bone mineral content and density were determined for 112 subjects with calcium intake below 800 mg/day.

RESULTS

Average calcium intake was found to be 1,260 mg/day, but 20% of all girls had a calcium intake below 800 mg/day. All low-energy diets were very low in calcium, as mean calcium intake per 1,000 calories was 411 128 grams. A large percentage of diets with less than 800 mg calcium were also deficient in phosphorus (95.2%), magnesium (84.8%). iron (90.5%) and zinc (100%). Due to differences in food sources. Jewish girls had more phosphorus in their diet, but less magnesium and iron compared to Arab girls. Calcium and zinc deficiencies in Jewish and Arab diets were similar. A negative correlation was found between body mass index (BMI) and age at menarche for all girls in the study. Bone mineral density (BMD) measured for girls with calcium intake below 800 mg/day distributed normally around the average when compared to age matched controls despite their low calcium intake. There was a strong positive correlation between BMD and bone mineral content (BMC) at all sites and body weights.

CONCLUSIONS

Low calcium intake, other nutritional deficiencies and delayed menarche due to low-energy diet in the growing period and in adolescence may prevent the formation of healthy bones. There is no evidence of lower bone mass among the low calcium intake group in the study population at this stage. It remains to be documented if the window of opportunity for optimal bone accretion for this group will be missed in the future. possibly leading to increased risk of osteoporosis.

Relation of collagen type I alpha 1 (COLIA 1) and vitamin D receptor genotypes to bone mass, turnover, and fractures in early postmenopausal women and to hip fractures in elderly people

Background: In a previous study, we showed an association between the vitamin D receptor (VDR) gene BsmI restriction fragment polymorphism and peak bone mass in young Finnish adults. Design: The previous finding prompted us to study the relationship of the same polymorphism, as well as of the polymorphism in the Sp1 binding site of the collagen type I alpha 1 (COLIA 1) gene, to bone mineral density (BMD). BMD was measured by dual-energy X-ray absorptiometry and adjusted for age, weight, height, and lifestyle factors. Also studied was the relationship of VDR and COLIA 1 genotypes to markers of bone turnover [serum osteocalcin, type I procollagen carboxy- (PICP), and aminoterminal (PINP) propeptide, and type I collagen carboxyterminal telopeptide (ICTP)] and bone fractures in 513 early postmenopausal women (1-5 years postmenopausal), as well as hip fractures in 172 very old people. Results: The BB, Bb, and bb genotypes of the VDR gene, as well as the SS, Ss, and ss genotypes of the COLIA 1 gene, were distributed similarly among 402 early postmenopausal women with osteopenia in the lumbar spine and among 111 women with normal BMD (P=0.12 for VDR, P=0.53 for COLIA 1). There was no relation between the VDR and COLIA 1 genotypes and lumbar spine BMD among osteopenic women, among normal women, or in the combined study population. Among the women with vertebral osteopenia, the femoral neck BMD did not associate significantly with the VDR or COLIA 1 polymorphisms. The frequencies of the different VDR and COLIA 1 genotypes were similar among women with or without a history of a low-energy fracture. There was a borderline association between the VDR genotype and serum osteocalcin concentrations, with the Bb genotype associated with the highest median level (P=0.037). In a population-based sample of very old individuals (>85 years), the frequencies of the different VDR and COLIA 1 genotypes were similar among those with (n=64) and without (n=108) a history of hip fracture. Conclusion: The present data suggest that, in the Finnish population, the VDR and COLIA 1 genotypes do not determine the bone mass of early postmenopausal women or their bone turnover rate. The polymorphisms are not associated with risk of hip fractures in elderly people or with low-energy fractures in early postmenopausal women.

The relative roles of intragenic polymorphisms of the vitamin d receptor gene in lumbar spine degeneration and bone density

STUDY DESIGN

A retrospective cohort study.

OBJECTIVES

To compare the magnitudes of the associations of TaqI polymorphisms of the vitamin D receptor gene with bone density and lumbar spine degeneration in the same sample.

SUMMARY OF BACKGROUND DATA

Vitamin D receptor gene variations are associated with osteoporosis, osteoarthritis, and disc degeneration. Their role in these conditions remains poorly understood.

METHODS

Bone density of the spine and femur were determined through DEXA, and lumbar disc degeneration was determined from magnetic resonance imaging assessments of signal intensity, disc narrowing, bulging, anular tears, herniations, and osteophytes. Associations between these measures and TaqI polymorphisms of the coding region of the Vitamin D receptor locus were examined in a population-based sample of 142 men.

RESULTS

The strongest associations were with signal intensity and anular tears, which were worse for the subjects with tt genotypes than for those with TT genotypes in the L4-S1 spine discs. Conversely, the prevalences of disc bulges and osteophytes were lowest for the tt genotype. Bone density, disc height, and herniations did not differ significantly by genotype.

CONCLUSIONS

The strongest association of Vitamin D receptor TaqI polymorphisms with degeneration in nonmineralized connective tissues suggests that the underlying mechanism of TaqI polymorphisms is not specific to bone. This study demonstrated for the first time that those with the tt genotype had more anular tears than those with the TT genotype, a finding that should stimulate further analyses of this gene in conditions that result in back pain. The apparent discrepancies of the associations of the tt genotype with lower signal intensity and more anular tears, but less bulges and osteophytes, could be explained if bulging and osteophytes primarily represented remodeling related to lifetime physical loading.

The genetics of osteoporosis: vitamin D receptor gene polymorphisms and circulating osteocalcin in healthy Irish adults

BACKGROUND

A relationship between bone turnover and the vitamin D receptor (VDR) genotype is reported in Australian subjects of UK-Irish descent. There is conflicting evidence of linkage between the VDR genotype and differences in bone mineral density. No such study has been carried out on a resident Irish population.

AIMS

This study examined the relationship between serum osteocalcin (a marker of bone turnover) and VDR genotype in Irish adults.

METHODS

One hundred and eighteen healthy Irish adults aged between 19 and 67 were recruited and had two fasting blood samples taken. One sample was analysed for osteocalcin by enzyme immunoassay. The other was used to isolate genomic DNA and determine VDR genotype.

RESULTS

Tt was the most prevalent VDR genotype (53%) and tt (15%) the least prevalent in this group of healthy Irish adults. The tt VDR genotype was associated with significantly higher levels of serum osteocalcin (29% and 40%) than the Tt or TT VDR genotypes.

CONCLUSIONS

These findings suggest that healthy Irish adults with the tt VDR genotype have higher rates of bone turnover than those with Tt or TTVDR genotypes. They may have a higher risk of low bone mineral density and osteoporosis in later life.

Pathogenesis of osteoporosis and challenges for drug delivery

Bone remodeling is under the control of local factors produced in the bone microenvironment. Many of the mechanisms responsible for coordination of activity between osteoclasts and osteoblasts, and how they are dysregulated in diseases of bone loss such as osteoporosis, are now being clarified. This leads to the possibility that bone remodeling can be manipulated by pharmacological means to reverse the changes caused by common bone diseases. However, many of the potential drugs suffer from non-selectivity in their effects. Targeting of drugs to active skeletal sites is of major interest to the pharmaceutical industry, and there are interesting and exciting possibilities which could lead to more specific therapies for the common diseases of bone loss. These will be reviewed in this chapter.

Vitamin D receptor gene polymorphism in multiple sclerosis and the association with HLA class II alleles

We have previously reported that the association between Bsm I polymorphism, one of the vitamin D receptor genes (VDRG) polymorphism, and multiple sclerosis (MS). In this report, we investigated the further possible role or relevance of VDRG in the pathogenesis of MS. Apa I polymorphism was detected by PCR-RFLP from the DNA of 77 conventional MS patients and 95 healthy controls. The study of the Bsm I and Apa I haplotypes was carried out by employing previously reported Bsm I data. The AA genotype and the [A] allele in the profiles were significantly more prevalent in MS patients than in controls (P=0.0070 and P=0.0321, respectively). In the [A] allele-positive MS patients, the positive rate of DPB1*0501 in HLA was significantly higher than that of the [A] allele-positive controls and that of the [A] allele-negative MS patients even when the corrected P value (P(corr)) was applied (P(corr)=0.0220 and P(corr)=0.0077, respectively). The frequency of DRB1*1501 was higher in the [A] allele-positive patients than in the [A] allele-positive controls and the [A] allele-negative patients (P(uncorr)=0.0431 and P(uncorr)=0.0089, respectively), but the P values did not reach statistical significance after P corrections. The rate of Bsm I and Apa I haplotypes was much higher in bA/bA-positive MS patients than in the controls (P=0.0003), and in the bA positive MS patients, the positive rate of DPB1*0501 was higher than that of the bA-positive controls and that of the bA-negative MS patients (P(corr)=0.0308 and P(corr)=0.0033, respectively). These results indicate that VDRG polymorphism may be associated with susceptibility to MS, and HLA alleles may correlate with risk for MS together with VDRG.