Lack of an intronic Sp1 binding-site polymorphism at the collagen type I alpha1 gene in healthy Korean women

Osteoporosis and its Association with Vitamin D Receptor, Oestrogen α Receptor, Parathyroid Receptor and Collagen Type I alpha Receptor Gene Polymorphisms with Bone Mineral Density: A Pilot Study from South Indian Postmenopausal Women of Tamil Nadu

The involvement of many putative genetic factors makes osteoporosis a complex disease. With increasing longevity of the Indian population, it's now being realized that, as within the West, osteoporotic fractures are also a significant explanation for morbidity and mortality in postmenopausal women. Studies have suggested that the genetic component liable for bone mass could be linked to single nucleotide polymorphisms. Therefore, this study is aimed to research the role of seven gene polymorphisms previously associated with bone phenotype in a cohort of postmenopausal South Indian women from Tamil Nadu. The subjects for the study (n = 300) included 100 osteoporotic women (age 59.3 ± 9.26), 100 osteopenic women (age 55.6 ± 8.17) and 100 non-osteoporotic women as controls (age 55.4 ± 8.85).Genetic polymorphisms were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism. Case-control genetic association analysis of BsmI of the VDR and BstBI of the PTH gene showed a significant allelic association with low bone mineral density amongst the osteoporotic postmenopausal women. The association of BMD with the VDR gene polymorphisms revealed that the average BMD in the BsmI polymorphism with the recessive genotype GG in osteoporotic women was significantly reduced compared with the average BMD in osteoporotic women with AA and AG genotypes. In the BstBI polymorphism, the BMD in the osteoporotic subjects were significantly lower in the AA group than in the GA and GG groups. These results provide evidence for an independent association between BMD and rs1544410 in VDR and rs6254 in PTH and may contribute in being a possible genetic marker for predicting the disease susceptibility in the population tested.

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

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

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

INTRODUCTION

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

MATERIAL AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Association of Collagen Type I α1 (COLIA1) Sp1 Polymorphism with Osteoporotic Fracture in Caucasian Post-menopausal Women: a Meta-analysis

This study was designed to summarize quantitatively the evidence for a relationship between collagen type I α1 (COLIA1) Sp1 polymorphism and osteoporotic fracture risk in Caucasian post-menopausal women. This meta-analysis included 16 studies, which analysed 2294 patients with fractures and 10285 controls. The combined results showed that there was a significant difference in genotype distribution (SS odds ratio [OR] 0.72; Ss OR 1.18; ss OR 1.97) between patients with fractures and controls. When stratifying by the fracture site, it was found that: (i) patients with vertebral fractures had a significantly higher frequency of the Ss genotype and a lower frequency of the SS genotype than controls; and (ii) patients with non-vertebral fractures had a significantly higher frequency of the ss genotype and a lower frequency of the SS genotype than controls. This meta-analysis suggests that the COLIA1 Sp1 polymorphism may be associated with osteoporotic fracture in Caucasian post-menopausal women.

Polymorphism of a COLIA1 gene Sp1 binding site in Korean women with pelvic organ prolapse

PURPOSE

To evaluate the possible influence of G-->T substitution at the Sp1-binding site of the COLIA1 gene on the risk of pelvic organ prolapse (POP).

MATERIALS AND METHODS

The study group consisted of 15 women with advanced stage POP. Fifteen control subjects with uterine myomas among the postmenopausal women were matched for age and parity. DNA was obtained from peripheral blood leukocytes. The fragments of the first intron of the COLIA1 gene were amplified by real time polymerase chain reaction. The polymorphism was identified using LightCycler Technology with hybridization probes. Sequencing reactions were performed on each template using commercial primer.

RESULTS

Two groups had no significant difference in medical history, surgical, and smoking history. The homozygous peaks in two groups were noted at 57 on melting curve analysis. Sequencing reactions confirmed the G/G alleles in the 30 specimens tested. We could not find any polymorphism at the Sp1-binding site in COLIA1 gene with advanced stage POP. Statistical significance was considered to be p < .05.

CONCLUSION

The polymorphism of the Sp1-binding site in the COLIA1 gene did not contribute to the development of POP in Korea.

The relationship between COL3A1 exon 31 polymorphism and pelvic organ prolapse

PURPOSE

We investigated the role of COL3A1 exon 31 polymorphism (a single base substitution from guanine to adenine at +2092), resulting in the replacement of alanine with threonine at the 698th amino acid of COL3A1, in the pathogenesis of pelvic organ prolapse.

MATERIALS AND METHODS

A total of 72 postmenopausal Korean women who were not on hormonal replacement therapy and who had a history of vaginal childbirth were enrolled in this study. The patient group consisted of 36 women diagnosed with stage II or greater pelvic organ prolapse irrespective of urodynamic stress incontinence. The control group consisted of 36 healthy volunteers with pelvic organ prolapse quantification system stage 0 or I disease without urodynamic stress incontinence. After extracting the genomic DNA from peripheral blood leukocytes the polymorphism of exon 31 of COL3A1 was typed by restriction fragment length polymorphism (Alu I restriction fragment length polymorphism) and confirmed by direct sequencing.

RESULTS

Frequency of the G allele was significantly higher in patients with pelvic organ prolapse than in controls (0.8 vs 0.6, p = 0.002). In women with the G allele the OR for pelvic organ prolapse was 3.2 (95% CI 1.4-7.3).

CONCLUSIONS

COL3A1 exon 31 polymorphism may have a role in determining the risk of pelvic organ prolapse in women with risk factors such as aging, vaginal childbirth and hypoestrogenism.

Genetic polymorphism in collagen type 1 alpha 2 intron 33 can be used for the initial screening of East Asians quickly and easily by a heteroduplex analysis

To save time and simplify the matching genetic information of bereaved family with the collected samples for identification of individuals in a mass-scale disaster and terrorism using molecular biological methods, we propose a method to initially screen samples according to different populations. We found a unique deletion (26822-3) in an allele that 62.0% of East Asian individuals had in intron 33 of type I collagen alpha 2 (COL1A2), while most Europeans and Africans did not have it. By making a heteroduplex complex, a visual discrimination was possible using 10% PAGE. A PCR and heteroduplex analysis could identify genetic polymorphism of COL1A2 intron 33 both clearly and accurately, even from decomposed samples or very small amounts of samples within a very short time period (approximately within 150min). As a result, genetic polymorphism of COL1A2 intron 33 is thus considered to be useful to quickly and easily screen East Asians from vast number of samples using a heteroduplex analysis. Consequently, we consider that an initial screening method for East Asians which use a heteroduplex analysis of genetic polymorphism of COL1A2 intron 33 can smoothly and effectively perform various identifications among East Asians when supplies are logistically poor after a mass-scale disaster or terrorism.

A specific haplotype in the 3' end of estrogen-receptor alpha gene is associated with low bone mineral density in premenopausal women and increased risk of postmenopausal osteoporosis

It is well established that the development of postmenopausal osteoporosis is under genetic influence. We have recently identified a synonymous single nucleotide polymorphism (SNP) in exon 8 of estrogen receptor-alpha (ERalpha) gene in the vicinity of the stop codon (G2014A) that is associated with an increased risk of postmenopausal osteoporosis. In the present study, we attempted to locate SNPs in the 3'-unstranslated region (3'UTR) of the ERalpha gene that are in linkage disequilibrium with the exon 8 SNP and assessed their utilization in the risk assessment of postmenopausal osteoporosis in 352 Thai postmenopausal women. The association with bone mineral density (BMD) in premenopausal women was also investigated in 202 premenopausal women. A C to A SNP 1,748 nucleotides distal to the end of the stop codon (C3768A) was identified. The C3768A SNP was not overrepresented in subjects with osteoporosis. However, the presence of the A-C haplotype allele based on the A2014 and C3768 alleles was significantly related to the risk of osteoporosis independently of age, body weight, the G2014A and C3768A SNPs (odds ratio 2.36, 95% CI 1.42-3.91). Moreover, the presence of the A-C haplotype allele was associated with lower femoral neck BMD in premenopausal women ( P =0.05). We concluded that a specific haplotype in the 3' end of the ERalpha gene is associated with lower BMD in premenopausal women and is associated with a higher risk of osteoporosis in postmenopausal women. It is likely that the haplotype allele exerts its influence on bone as early as during young adulthood to increase the risk of osteoporosis later in life.

The relationship between COLI A1 polymorphisms (Sp 1) and COLI A2 polymorphisms (Eco R1 and Puv II) with bone mineral density in Chinese men and women

Polymerase chain reaction was used to amplify across variable restriction sites of the COLI A1 and COLI A2 genes that encode the alpha 1 and 2 subunits of type I collagen. The relationship between these polymorphisms and bone mineral density (BMD) was studied in 683 Chinese men and women. In 100 men and women, COLI A1 Sp1 polymorphism was not found, which was consistent with other previous studies in Asian populations. However a statistically significant relationship was observed between COLI A2 Eco R1 and Puv II genotypes among the Chinese men studied. The mean BMD was consistently lower in men of the EE and PP genotype (P < 0.05 by analysis of variance [ANOVA]) than in men of the ee and pp genotypes. However, no association between BMD and the Eco R1 or Puv II genotypes was observed in Chinese women (P > 0.05 by ANOVA). We conclude that the COLI Al Sp1 binding site is absent in Hong Kong Chinese, whereas the COLI A2 Eco R1 and Puv II genetic polymorphisms may be associated with the BMD of elderly Chinese men.

Current limitations of SNP data from the public domain for studies of complex disorders: a test for ten candidate genes for obesity and osteoporosis

BACKGROUND

Public SNP databases are frequently used to choose SNPs for candidate genes in the association and linkage studies of complex disorders. However, their utility for such studies of diseases with ethnic-dependent background has never been evaluated.

RESULTS

To estimate the accuracy and completeness of SNP public databases, we analyzed the allele frequencies of 41 SNPs in 10 candidate genes for obesity and/or osteoporosis in a large American-Caucasian sample (1,873 individuals from 405 nuclear families) by PCR-invader assay. We compared our results with those from the databases and other published studies. Of the 41 SNPs, 8 were monomorphic in our sample. Twelve were reported for the first time for Caucasians and the other 29 SNPs in our sample essentially confirmed the respective allele frequencies for Caucasians in the databases and previous studies. The comparison of our data with other ethnic groups showed significant differentiation between the three major world ethnic groups at some SNPs (Caucasians and Africans differed at 3 of the 18 shared SNPs, and Caucasians and Asians differed at 13 of the 22 shared SNPs). This genetic differentiation may have an important implication for studying the well-known ethnic differences in the prevalence of obesity and osteoporosis, and complex disorders in general.

CONCLUSION

A comparative analysis of the SNP data of the candidate genes obtained in the present study, as well as those retrieved from the public domain, suggests that the databases may currently have serious limitations for studying complex disorders with an ethnic-dependent background due to the incomplete and uneven representation of the candidate SNPs in the databases for the major ethnic groups. This conclusion attests to the imperative necessity of large-scale and accurate characterization of these SNPs in different ethnic groups.

Differentiation of Caucasians and Chinese at bone mass candidate genes: implication for ethnic difference of bone mass

Bone mineral density (BMD) is an important risk factor for osteoporosis and has strong genetic determination. While average BMD differs among major ethnic groups, several important candidate genes have been shown to underlie BMD variation within populations of the same ethnicity. To investigate whether important candidate genes may contribute to ethnic differences in BMD, we studied the degree of genetic differentiation among several important candidate genes between two major ethnic groups: Caucasians and Chinese. The genetic variability of these two populations (1131 randomly selected individuals) was studied at six restriction sites exhibiting polymorphisms of five important candidate genes for BMD: the BsaHI polymorphism of the calcium-sensing receptor (CASR) gene, the SacI polymorphism of the alpha2HS-glycoprotein (AHSG) gene, the PvuII and XbaI polymorphisms of the estrogen receptor alpha (ESR1) gene, the ApaI polymorphism of the vitamin D receptor (VDR) gene, and the BstBI polymorphism of the parathyroid hormone (PTH) gene. The two ethnic groups showed significant allelic and genotypic differentiation of all the polymorphisms studied. The mean FST was 0.103, which significantly differed from zero (P < 0.01). The Chinese population had lower mean heterozygosity (0.331) than the Caucasian one (0.444); the CASR-BsaHI and PTH-BstBI polymorphisms contributed most significantly to this difference. Analysis of the intra- and inter-population variability suggests that various types of natural selection may affect the observed patterns of variation at some loci. If some of the candidate genes we studied indeed underlie variation in BMD, their population differentiation revealed here between ethnic groups may contribute to understanding ethnic difference in BMD.

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.

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.

Polymorphism in the type I collagen (COLIA1) gene and risk of fractures in postmenopausal women

Twin and family studies have demonstrated that a large part of a population's variance in bone mineral density (BMD) is attributable to genetic factors. A polymorphism in the collagen type I alpha1 (COLIA1) gene has recently been associated with low bone mass and fracture incidence. We analyzed the relationship between COLIA1 gene polymorphism, lumbar spine and hip BMD, and fracture prevalence in a population of 319 postmenopausal women classified by WHO standards, including 98 nonosteoporotic women (NOPW) and 221 osteoporotic postmenopausal women (OPW), divided into 139 osteoporotic women without fracture (OPWnF) and 82 osteoporotic women with fracture (OPWwF). The COLIA1 genotype was assessed by polymerase chain reaction and BalI endonuclease digestion. Genotype frequencies for the total group were 49.2% GG homozygotes, 39.5% GT heterozygotes, and 11.3% TT homozygotes. We found significant differences in the percentage of homozygous TT between NOPW and OPW (6.1% and 13.6%, respectively). Significantly, the occurrence of genotype TT in OPWnF was 6.2%, and 28% in OPWwF. We observed no associations between the COLIA1 genotype and lumbar spine and hip BMD. The prevalence of fractures varied significantly by genotype: GG, 26.1%; GT, 15.9%; and TT, 58.3%. Logistic regression analysis of fracture prevalence showed that, for prevalent fractures, the women with the TT genotype had a 5.9-fold increased risk when compared with the other genotypes (GG + GT). When prevalence was adjusted for age, body mass index, and BMD, the fracture risk was 4.8 for the TT group vs. the genotype GG, whereas it was 0.6 for the GT genotype. In conclusion, we found the COLIA1 Sp1 TT genotype to be associated with an increased fracture risk in postmenopausal women. Interestingly, this genotype-dependent risk could not be explained completely by BMD differences.

The genetics of osteoporosis

A genetic component clearly contributes to bone mass determination by influencing peak bone mass acquisition or, to a lesser degree, bone loss later in life. The analysis of genetic markers for osteoporosis is complex because multiple genes are involved and because osteoporosis is a multifactorial disease. The influence of a number of candidate gene alleles on bone mass has been studied in various populations. Results have been inconsistent and, at times, contradictory, as illustrated by studies on the vitamin D receptor gene. The most conclusive finding is the association linking the Sp1 polymorphism of type I collagen to bone mineral density and osteoporotic fractures. Polymorphisms of other genes either have very little influence or remain unexplored. In all likelihood, the best predictive value will be obtained by using a combination of several gene polymorphisms.

Association of collagen Ialpha 1 Sp1 polymorphism with the risk of prevalent fractures: a meta-analysis

Several studies have addressed the effect of the Spl polymorphism of the collagen Ialpha 1 (COLIA1) gene on the prevalence of fractures. The results are not in full agreement on whether this polymorphism is associated with fracture risk. To clarify this uncertainty, we performed a meta-analysis including 13 eligible studies with 3641 subjects. The COLIA1 Spl polymorphism showed a dose-response relationship with the prevalence of fractures. The risk was 1.25-fold (95% CI, 1.09-1.45) in Ss heterozygotes versus SS homozygotes, 1.68-fold (95% CI, 1.35-2.10) in ss homozygotes versus SS homozygotes, and 1.35 (95% CI, 1.04-1.75) for ss homozygotes versus Ss heterozygotes by random effects calculations. There was modest heterogeneity for these three effect estimates (p value for heterogeneity, 0.17, 0.16, and 0.08, respectively). The Sp1 polymorphism effects possibly were larger when the analysis was limited to studies considering only vertebral fractures (pooled risk ratios [RR], 1.30, 2.07, and 1.46, respectively). Conversely, the Spl polymorphism effects tended to be smaller in studies with mean patient age > or = 65 years than in studies with younger patients on average, but the differences were not formally significant. We estimated the total average attributable fraction (AF) of fractures due to the s allele in European/U.S. populations as 9.4%. The meta-analysis suggests an important role for the Spl polymorphism in the regulation of fracture risk; however, potential heterogeneity across ethnic groups, age groups, and skeletal sites may be important to clarify in future studies. Very large studies or meta-analyses are required to document subtle genetic differences in fracture risk.

Absence of high-risk "s" allele associated with osteoporosis at the intronic SP1 binding-site of collagen Ialpha1 gene in Southern Chinese

The Sp1 polymorphism in the first intron of the collagen Ialpha1 gene was recently described to be associated with low bone mineral density (BMD) and increased fracture risk in Caucasian populations. The impact of this gene was assessed in a Southern Chinese population. One hundred and eighty-one women, aged 51.1+/-8.8 yr were evaluated for the Sp1 polymorphism. Twenty-two per cent of the women were classified as having osteoporosis on the basis of a T-score at the lumbar spine or the hip below -2.5 with or without a prevalent fracture. Genotype analysis was performed by PCR amplification and restriction enzyme digestion. Single-strand conformational polymorphism analysis (SSCP) was performed in 65 randomly selected samples to search for any polymorphic site in the PCR amplified region. The results showed that no restriction enzyme site could be identified in any of the 181 samples analyzed. Moreover, SSCP analysis revealed no polymorphism in the PCR amplified region of the first intron of the collagen Ialpha1 gene. In conclusion, the "s" allele, associated with low BMD and increased fracture risk in Caucasians, is non-existent or very rare in the Southern Chinese population. The absence of this "high risk" allele may in part account for the reduced fracture risk observed in the Chinese in comparison to Western populations.

COLIA1 polymorphism contributes to bone mineral density to assess prevalent wrist fractures

Wrist fractures associated with postmenopausal women are only partially explained by osteoporosis. Recent studies have shown that polymorphism of an Spl binding site in the first intron of the collagen I alpha 1 gene (COLIA1) may determine risk for vertebral and nonvertebral fractures in post-menopausal women independent of bone mass. We investigated the relationship between the COLIA1 polymorphism, lumbar spine and femoral neck bone mineral density (BMD), ultrasound stiffness of the heel, anthropometric variables, and risk for wrist fractures in 126 Czech postmenopausal women with low bone mass who suffered one or more wrist fracture in the last 5 years and in 126 postmenopausal women with low bone mass without any fracture. Genotypes for the Spl COLIA1 polymorphism were determined by polymerase chain reaction, digestion with Ball restriction enzyme, and agarose gel electrophoresis. The test discriminates two alleles, S and s, which correspond to the presence of guanine and thymidine, respectively, at the first bases in the Spl-binding site in the first intron of the gene for CO-LIA1. No significant differences were found between the fracture and control group with regard to age, weight, and years since menopause. However, BMD of the lumbar spine and femoral neck and ultrasound stiffness of the heel were significantly lower in patients with prevalent wrist fracture. Femoral neck BMD was the strongest determinant of prevalent fracture of the wrist. COLIA1 genotyping significantly strengthened prediction of prevalent fracture of the wrist. After multivariate adjustment, women in the Ss group had 2.0 times the risk of the women in the SS group (95% confidence interval [CI] = 1.1-3.8), and the women in the ss group had 2.8 times the risk of the women in the SS group (95% CI = 0.5-14.6). The overall gene-dose effect was an odds ratio of 2.1 per copy of the "s" allele (95% CI = 1.2-3.8). In the stepwise logistic regression, COLIA1 acted synergistically with femoral neck BMD and weight in increasing prediction of wrist fracture. The results demonstrate that COLIA1 Sp1 polymorphism is associated with an increased risk of wrist fracture in postmenopausal women independent of BMD and may be helpful in clinical practice by identifying patients with an increased fracture risk.

Genetic aspects of osteoporosis

At a given age, bone mass represents the difference between the maximal amount of bone mineral mass gained during growth (peak bone mass) and post-menopausal and/or senile bone loss. Twins and parents-offspring models have shown a strong inheritance of peak bone mass and it is now known that familial resemblance in various bone mass constituents is detectable well before the pubertal growth spurt. Recent developments in the molecular epidemiology of osteoporosis have focused on the association between areal bone mineral density and common polymorphisms in several candidate genes. Among them, vitamin D receptor (VDR), estrogen receptor and collagen-1 -alpha-1 (COL1A1) genes have been the most extensively investigated. Although controversial results have been reported and osteoporosis cannot be predicted by any single polymorphic gene marker, recent advances in this field have emphasized the complexity of bone mineral mass determination, because of gene-gene and gene-environment interactions.