Genetic factors play an important role in the pathogenesis of osteoporosis, and recent studies have shown that a polymorphic Sp1 binding site in collagen type I alpha1 (COLIA1) gene is associated with bone mass and vertebral fractures in women from the U.K. Information on the predictive value of the COLIA1 Sp1 polymorphism in other populations is limited, however, and no studies have yet been performed in osteoporotic males. In view of this, we analyzed COLIA1 genotypes in relation to bone density and biochemical markers of bone turnover and the presence of osteoporotic fractures in a case-control study of Danish men and women. COLIA1 genotype was determined by polymerase chain reaction analysis of genomic DNA extracted from peripheral blood samples and related to bone mass, biochemical markers of bone turnover, and the presence of fracture in a study of 375 osteoporotic vertebral fracture patients and normal controls. There was no significant effect of COLIA1 genotype on bone mass or biochemical markers when data from the control group (n = 195) and fracture group (n = 180) were analyzed separately. However, the genotype distribution was significantly different in the fracture cases compared with age-matched controls (chi2 = 16.48, n = 249,p = 0.0003) due mainly to over-representation of the ss genotype in the fracture patients (14.3% vs. 1.4%), equivalent to an odds ratio for vertebral fracture of 11.83 (95% confidence interval 2.64-52.97) in those with the ss genotype. Similar differences in genotype distribution between osteoporotic patients and controls were observed in both men (chi2 = 11.52, n = 95, p = 0.0032, OR = 2.04) and women (chi2 = 6.90, n = 154, p = 0.032, OR = 1.37). In keeping with the above, logistic regression analysis showed that the ss genotype was an independent predictor of osteoporotic fracture (p = 0.028). This study confirms that the COLIA1 Sp1 polymorphism is significantly associated with osteoporotic vertebral fractures. The association is seen in both men and women, and the effect on fracture risk appears to be partly independent of bone mineral density. Our results raise the possibility that genotyping at the Sp1 site could be of clinical value in identifying individuals at risk of osteoporotic fractures in both genders.
Estrogen receptor alpha (ER alpha) and collagen IA1 (COLIA1) genes have been suggested as possibly implicated in reduced bone mineral density (BMD). The present study investigated the occurrence of association and linkage disequilibrium between radiographic hand BMD and polymorphic alleles of ER alpha and COLIA1 genes, in human pedigrees of a Chuvasha population in Russia. The study sample included 463 members of 113 pedigrees, mostly nuclear families. We performed association and transmission disequilibrium test (TDT) analyses of the combined PvuII and XbaI RFLPs alleles on the same chromosome (haplotype) of the ER alpha gene with BMD Z scores of cancellous or cortical bone in the hand phalanges. The association analyses were performed separately for both genders in the parental generation, i.e., 'fathers' (n = 114; average age 64.2 y) and 'mothers' (n = 122; average age 62.7 y). The Px haplotype was associated significantly with lower BMD Z scores in 'mothers' only. The difference between subjects who carried one or two copies of the Px haplotype and those lacking it was 0.68 Z scores, P = 0.003 and 0.51 Z scores, P = 0.025 for cancellous and cortical bone, respectively. Multiple linear regression model with age, height, weight, and Px haplotype status as predictors explained 26.7% and 28.3% of the total observed variance in BMD with Px haplotype as independent predictor explaining 5.9%; P = 0.002 and 3%; P = 0.028 (cancellous and cortical bone, respectively). Results of t-TDT for triads of two parents and just one of their female offspring (but not male offspring) suggested the existence of linkage disequilibrium between the two loci of Px haplotype and BMD trait (P = 0.047). No association was found between polymorphic alleles of COLIA1 gene and BMD, but 'mothers' with combined genotypes of Px haplotype of ER alpha gene and "s" allele of COLIA1 gene had the lowest mean Z scores (-0.944 and -0.788 for cancellous and cortical bone, respectively). We conclude that the Px haplotype of the ER alpha gene is associated with low BMD values in females, as the phenotype is gender dependent (the association was not observed in males), and the "s" allele of COLIA1 gene in combination with this haplotype contributes to reduced BMD.
Bone mineral density (BMD) and bone strength are predictive parameters for the development of osteoporosis and related fracture later in life. Although it is well known that BMD and bone strength have a high heritability, not much of the variation is already explained. Mice models showed that sFRP1 has an influence on bone formation. Therefore this study aimed to investigate the effect of common genetic variation on BMD and bone strength in Caucasian men of different ages. Using HapMap we selected 13 tagSNPs which tag most common genetic variation in and around sFRP1 and we genotyped these SNPs in the young cohort of the Odense Androgen Study (OAS). The OAS includes a total of 1383 Danish men from two different age groups ([20-29 years]: N=783; [60-74 years]: N=600) and is well characterised. The subjects were phenotyped for BMD at several sites, and additionally for body composition and hip geometry parameters. Based on the results of the young cohort we selected three SNPs for further analysis in the complete OAS population. To conclude we tried to replicate the results of two SNPs in an independent population of 994 Belgian men. We found a strong association for rs9694405 with BMI as well in both cohorts separately as in the whole OAS population. Further we found rs4736965 associated with several hip geometry parameters in the same population. However we were not able to replicate those results in the Belgian population. At last we found in the OAS population age specific effects for rs10106678 with whole body BMD and waist to hip ratio.
By means of different genetic association studies the SOST gene, encoding sclerostin, has repeatedly been suggested to regulate bone mineral density (BMD) and osteoporosis susceptibility. This study aimed at a further understanding of the importance of two previously studied single-nucleotide polymorphisms in the SOST gene, rs10534024 (SRP3) and rs9902563 (SRP9), in the Odense Androgen Study (OAS) cohort. This cohort includes a total of 1,383 Danish men from two different age groups, 20-29 years (n = 783) and 60-74 years (n = 600), and is well characterized. Subjects were phenotyped for BMD at several sites and additionally for body composition and hip geometric parameters. In a combined analysis of the young and the elderly OAS, no associations were found for SRP3 either with BMD or with hip geometry. Instead, we found that this polymorphism had a relatively large effect on weight (-1.149 kg) and body mass index (-0.389 kg/m(2)) (P = 0.021 and 0.006 under a codominant model). For SRP9, a significant association was found for femoral neck BMD (+0.020 g/cm(2), P = 0.020) and a trend toward significance for hip geometry (buckling ratio of the narrow neck) but only when considering a recessive effect of the minor allele (C). No age-specific effects were found for either of the two SNPs. In summary, we are the first to find interesting associations between SRP3 and body composition. For SRP9, we replicated a site-specific association with femoral neck BMD. In addition, we report a novel association for this polymorphism with hip geometry.
Osteoporosis is a bone disease characterized by low bone mineral density (BMD), a highly heritable polygenic trait. Women are more prone than men to develop osteoporosis owing to a lower peak bone mass and accelerated bone loss at menopause. Lack of estrogen thus is a major risk factor for osteoporosis. In addition to having strong similarity to the estrogen receptor 1 (ESR1), the orphan nuclear estrogen-related receptor gamma (ESRRgamma) is widely expressed and shows overlap with ESR1 expression in tissues where estrogen has important physiologic functions. For these reasons, we have undertaken a study of ESRRgamma sequence variants in association with bone measurements [heel quantitative ultrasound (QUS) by measurements of broadband ultrasound attenuation (BUA), speed of sound (SOS), and stiffness index (SI) and dual-energy X-ray absorptiometry (DXA) at the femoral neck (FN) and lumbar spine (LS)]. A silent variant was found to be associated with multiple bone measurements (LS, BUA, SOS, and SI), the p values ranging from .006 to .04 in a sample of 5144 Quebec women. The region of this variant was analyzed using the HapMap database and the Gabriel method to define a block of 20 kb. Using the Tagger method, eight TagSNPs were identified and genotyped in a sample of 1335 women. Four of these SNPs capture the five major block haplotypes. One SNP (rs2818964) and one haplotype were significantly associated with multiple bone measures. All SNPs involved in the associations were analyzed in two other sample sets with significant results in the same direction. These results suggest involvement of ESRRgamma in the determination of bone density in women.
In order to identify genetic effects of allelic variation on bone mineral density (BMD), association studies have been performed recently. Examining the relation between PvuII and XbaI restriction fragment length polymorphism (RFLPs) at the estrogen receptor (ER alpha) gene and BMD, in women or men, have yielded conflicting results. We analyzed the association between this polymorphism and BMD Z score values of cancellous bone at the 3rd finger in 344 members of nuclear families of European population, Chuvasha, living in Russia. The population sample included 183 males, aged 18-84, and 161 females, aged 23-79. The analysis has been performed separately for both sexes and for both generations (parents and offspring). We used a novel direct haplotyping method, which determines simultaneously each of the PvuII and XbaI RFLPs and their relation to each other. The haplotypes were represented as the combination of both polymorphic sites on the same chromosome, by using P/p and X/x for PvuII and XbaI restriction sites, respectively. The subjects were classified into 3 groups of genotypes: A = PXPX (homozygote for the PX haplotype); B = PXPx, PXpx (the heterozygotes for the PX haplotype); C = PxPx, Pxpx, pxpx (genotypes that are lacking the PX haplotype). The PXPX genotype (A) was associated with higher BMD Z score values in comparison to the genotypes that are lacking the PX haplotype (C), in total males [0.618 vs. -0.133 (p = 0.004)] and for the "sons" generation [0.724 vs. -0.198 (p = 0.02)]. Similar tendency was observed for the "fathers" generation (0.539 vs. -0.085), though the difference did not approach statistical significance (p = 0.087). These findings were not found in the female samples, nor in the "mothers" or "daughters" generations. The question if there are differences in the mode of action of estrogen through its receptor on bone mass, between the genders or between the males' generations, have to be further investigated.
Peak bone mass achieved in adolescence is a determinant of bone mass in later life. In order to identify genetic variants affecting bone mineral density (BMD), we performed a genome-wide association study of BMD and related traits in 1518 children from the Avon Longitudinal Study of Parents and Children (ALSPAC). We compared results with a scan of 134 adults with high or low hip BMD. We identified associations with BMD in an area of chromosome 12 containing the Osterix (SP7) locus, a transcription factor responsible for regulating osteoblast differentiation (ALSPAC: P = 5.8 x 10(-4); Australia: P = 3.7 x 10(-4)). This region has previously shown evidence of association with adult hip and lumbar spine BMD in an Icelandic population, as well as nominal association in a UK population. A meta-analysis of these existing studies revealed strong association between SNPs in the Osterix region and adult lumbar spine BMD (P = 9.9 x 10(-11)). In light of these findings, we genotyped a further 3692 individuals from ALSPAC who had whole body BMD and confirmed the association in children as well (P = 5.4 x 10(-5)). Moreover, all SNPs were related to height in ALSPAC children, but not weight or body mass index, and when height was included as a covariate in the regression equation, the association with total body BMD was attenuated. We conclude that genetic variants in the region of Osterix are associated with BMD in children and adults probably through primary effects on growth.
The aim of this study was to determine the genetic, anthropometric and metabolic features in an unselected population of adult Norwegian patients with 21-hydroxylase deficiency (21OHD). PATIENTS, METHODS AND DESIGN: Sixty-four 21OHD patients participated (23 men and 41 women; median age 38.5 years; range 19-72 years) in a cross-sectional study including DNA sequencing of CYP21A2, anthropometric measurements including dual X-ray absorptiometry scanning and biochemical analyses. The results were compared with reference cohorts from the general population.
We identified four novel and plausibly disease-causing CYP21A2 mutations. Gene deletions/conversions (42.1% of alleles), the splice mutation I2 splice (23.0%) and point mutation I172 N (22.2%) were common. The genotype corresponded to clinical phenotype in 92% of the patients. The prevalence of osteopenia was 48% in males and 34% in females. Both men and women had normal BMI but markedly increased fat mass compared with the normal population. Diastolic blood pressure was higher than normal. Thirty-nine per cent of the women had testosterone levels above the normal range; 13% of the men had testosterone levels below normal. Reduced final height was more pronounced in men (median -11.2 cm, -1.77 SDS) than in women (-6.3 cm, -1.07 SDS).
In this population-based survey of 21OHD, we identified four novel mutations and high concordance between genotype and phenotype. The patients had increased fat mass, increased diastolic blood pressure, reduced final height and high frequency of osteopenia among males. These results show unfavourable metabolic features in 21OHD patients indicating a need for improvement of treatment and follow-up.
Because of the importance of the Wnt pathway in the development and maintenance of both adipose and bone tissue, we wanted to evaluate the involvement of WNT10B, a Wnt pathway activator, in adipogenesis and osteoblastogenesis in humans. Genetic association between WNT10B polymorphisms and adiposity parameters as well as bone mineral density (BMD) measurements was analysed in two independent populations. The first is a population of 1,228 Danish men (702 aged 20-29 years; 532 aged 60-74 years) from the Odense Androgen Study (OAS), which was designed as a cross-sectional, population-based study. The second population, called SIBLOS, includes 922 Belgian men (34 ± 5 years old) and contains siblings selected from over 500 families. Four tagSNPs (rs833840, rs833841, rs10875902 and rs4018511) that capture variation of ten SNPs (MAF > 5 %) in a 15.2 kb region spanning the WNT10B gene and its flanking regions were genotyped. Although no association with body mass index was found, we found all tagSNPs to be associated with BMD parameters (BMD whole body, total hip and femoral neck) and height in the OAS population. The association of rs10875902 was most prominent (nominal p = 0.012) and confirmed a previously shown negative effect on BMD. No significant associations were observed in the SIBLOS population. In the present study, no association between WNT10B polymorphisms and adiposity parameters was found. However, our results clearly illustrate a role for WNT10B variants in determining human BMD. The effect of WNT10B polymorphisms on height should be evaluated in additional populations.
Polymorphisms in the CYP2R1 gene encoding Vitamin D 25-hydroxylase have been reported to correlate with circulating levels of 25-OH vitamin D3 (25(OH)D). It is unknown whether these variations also affect overall bone metabolism. In order to elucidate the overall associations of polymorphisms in the CYP2R1, we studied haplotype tagging single nucleotide polymorphisms (SNPs) in the gene and serum levels of 25(OH)D, calcium, phosphate, parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF23), as well as bone mineral density (BMD).
Baseline data on serum parameters and BMD from MrOS Sweden, a prospective population-based cohort study of elderly men (mean age 75 years, range 69-81), were analyzed. Genotyping was performed for eight SNPs covering the CYP2R1 gene in 2868 men with available samples of DNA. Subjects were followed up concerning incidence of fracture during five years.
There was a significant genetic association with circulating levels of 25(OH)D (4.6-18.5% difference in mean values between SNP alleles), but there were no correlations with levels of calcium, phosphate, PTH or FGF23 for any genetic variant. No differences were found in fracture incidence between the variants. There was an inverse relationship between lower BMD and concomitant higher 25(OH)D for three of the haplotypes (p