两个新钙感觉受体基因多态性与中国女性骨密度相关性研究

目的钙感觉受体(CaSR)基因是引人关注的与骨质疏松症敏感性相关的侯选基因,为了解CaSR基因两个新多态位点与中国女性人群骨密度(BMD)的关系。方法采用双能X线吸收仪对352名研究对象进行腰椎及股骨扫描,应用PCR限制性片段长度多态性(PCRRFLP)方法检测CaSR基因R990G和E1011Q两个新多态位点基因型,用广义线性模型分析CaSR基因与腰椎及股骨BMD关系。结果发现CaSR基因的E1011Q多态位点在调整相关影响因素前后均与女性股骨颈、股骨柄和股骨三角区的BMD呈显著相关,P值分别为0.011、0.04和<0.001;R990G多态位点在调整影响因素前后,显示与女性股骨颈密度有相关趋势P=0.055,而A986S基因多态未显示与股骨、腰椎BMD相关。结论这一结果提示,CaSR基因E1011Q多态性可能是中国女性股骨BMD降低的危险因素。这个发现的意义及是否适用于大样本人群还有待进一步研究证实。     

雌激素受体α基因多态性与新疆维、汉两民族妇女腰椎峰值骨密度的关系

目的探讨新疆地区维吾尔族(维族)、汉族两民族妇女雌激素受体(ER-α)基因多态性与腰椎峰值骨密度的关系。方法分别对乌鲁木齐地区无亲缘关系、年龄20～40岁的160例汉族健康妇女和135例维吾尔族健康妇女进行PCR-RFLP测定雌激素受体α基因XbaI及PvuⅡ多态性,用定量CT(QCT)骨密度仪测定腰椎骨密度(BMD)。结果维、汉族女性骨密度均值比较,差异有显著性(P<0.05)。维、汉族妇女ER-α的基因型及等位基因频率分布均符合Hardy-Weinberg平衡定律;XbaI及PvuⅡ多态性基因型频率及等位基因频率在维、汉两民族妇女中比较,差异均有显著性(P<0.05)。协方差方法分析各基因型与BMD的关系显示:仅PvuⅡ多态性与维族妇女L2-4BMD值显著相关(P<0.05),Pp/pp基因型在L2-4BMD值明显低于PP基因型,差异有显著性(P<0.05)。结论 ER-α基因XbaI多态性对新疆地区维、汉族妇女腰椎峰值骨量无潜在影响;PvuⅡ多态性对维族妇女腰椎峰值骨量的达到和维持有关,与汉族无关。     

Relations between interleukin-1, its receptor antagonist gene polymorphism, and bone mineral density in postmenopausal Korean women

We investigated the relation between polymorphisms in the interleukin-1(IL-1) and IL-1 receptor antagonist (IL-1ra) gene, and bone mineral density (BMD) in postmenopausal Korean women. The IL-1α C⁻⁸⁸⁹T polymorphism, and IL-1β C⁻⁵¹¹T polymorphism were examined by restriction fragment length polymorphism, and 86-bp variable number tandem repeat polymorphism in the IL-1ra gene was analyzed by the polymerase chain reaction and electrophoresis in 202 postmenopausal Korean women. Serum osteocalcin, and C-telopeptide of type I collagen were measured using a radioimmunoassay and enzyme-linked immunosorbent assay, respectively. BMD at the lumbar spine and proximal femur was measured by dual-energy X-ray absorptiometer. No significant differences in BMD or in serum bone markers levels were noted across the IL-1α or IL-1β genotype. There were no significant differences in the distribution of IL-1α or IL-1β genotype according to the status of bone mass. BMD in women carrying the A2 allele of the IL-1ra gene was significantly lower than those without this allele, and the A2 allele was more frequent in osteoporotic women than in normal women. These data suggest that IL-1ra gene VNTR polymorphism is a genetic factor that may affect BMD in Korean women.     

Relationships between the insulin-like growth factor I (IGF-I) receptor gene G3174A polymorphism, serum IGF-I levels, and bone mineral density in postmenopausal Korean women

We investigated the relationships between the IGF-I receptor gene G3174A polymorphism, serum IGF-I levels, and bone mineral density (BMD) in postmenopausal Korean women. The IGF-I receptor gene G3174A polymorphism was analyzed in 367 postmenopausal Korean women. Serum levels of IGF-I, bone turnover markers (osteocalcin, bone alkaline phosphatase, carboxy-terminal cross-linking telopeptide of type I collagen), and BMD at the lumbar spine and proximal femur were measured. The frequencies of the AA, GA, and GG genotypes were 10.9%, 44.1%, and 45.0%, respectively. BMD at the lumbar spine was significantly higher for the AA genotype than the other genotypes and showed an A allelic dose effect; however, no significant differences in BMD were observed at the proximal femur with respect to genotype. No differences were noted between the three genotypes in terms of serum levels of IGF-I or bone turnover markers. Women with low BMD showed a lower prevalence of the AA genotype and A allele than age-matched women with normal BMD. Women with the AA genotype were found to have about half the risk of a low BMD than women with other genotypes. In conclusion, IGF-I receptor gene G3174A polymorphism is associated with lumbar spine BMD in postmenopausal Korean women.     

Lack of Influence of Collagen Type Iα1 Sp1 Binding Site Polymorphism on the Rate of Bone Loss in a Cohort of Postmenopausal Danish Women Followed for 18 Years

A polymorphism in an Sp1 site in the collagen Iα1 (COLIA1) gene has recently been identified and the Ss and ss genotypes were shown to be potentially important determinants of low bone mass in postmenopausal women. Additionally, in a Dutch population, the association of the COLIA1 polymorphism with low bone mineral density (BMD) was more pronounced with increasing age, suggesting a genotype effect on the rate of bone loss. We have investigated the relationship between the COLIA1 Sp1 polymorphism and the rate of bone loss in a longitudinal study with a total of 133 postmenopausal women followed for 18 years. The frequencies of the genotypes were SS 70.7%, Ss 27.8%, ss 1.5% and were in Hardy-Weinberg equilibrium. No association of the COLIA1 genotype with rate of bone loss was detected and there was no difference between the genotype groups with respect to BMD at the femoral neck or lumbar spine. Women with the Ss or ss genotypes, who have been postulated to have low BMD, had even higher BMD at the lower forearm than women with the SS genotype. The levels of serum osteocalcin and urinary collagen type I degradation products were not found to be associated with the COLIA1 Sp1 polymorphism. In conclusion, this study does not support the hypothesis that the Ss COLIA1 genotype predisposes women to increased rate of bone loss or low BMD. However, because of a low absolute number of the ss genotype, it was not possible to reach a conclusion on this particular genotype with regard to an association with low BMD or rate of bone loss. Received: 25 January 1999 / Accepted: 12 January 2000     

Lack of association between interleukin-1 receptor antagonist protein gene polymorphism and bone mineral density in Hungarian postmenopausal women

The major determinant for risk of osteoporosis in later life is bone mineral density (BMD) attained during early adulthood. Bone mineral density is a complex trait that is presumably influenced by multiple genes. Interleukin-1 receptor antagonist protein (IL-1RN) is an attractive candidate gene for osteoporosis susceptibility, because IL-1RN completely inhibits the stimulatory effects of interleukin-1 (IL-1) on bone resorption in organ cultures and has been implicated in the pathogenesis of osteoporosis. In addition, the IL-1RN gene contains a variable-number tandem repeat polymorphism (VNTR) in intron 2 with three potential protein-binding sites. Recently, an association has been found between this polymorphism and postmenopausal bone loss in the spine. In this study, we use the previously described IL-1RN polymorphism to test for an association between this polymorphism and bone mineral density in our population of postmenopausal women. There was no correlation between alleles or genotypes and BMD in the 286 subjects. Dividing subjects into osteoporotic and healthy groups (osteoporotics and controls), we found no difference in the distribution of alleles or genotypes between groups. We found no association between IL-1RN alleles or genotypes and BMD either at the lumbar spine or the femoral neck within groups. Our data do not support the hypothesis that this IL-1RN gene VNTR polymorphism has an impact on bone mass in postmenopausal women.     

Transforming growth factor-beta1 gene polymorphism, bone turnover, and bone mass in Italian postmenopausal women.

Transforming growth factor beta1 (TGF-beta1) is abundant in bone and is an important regulator of the osteoclastic-osteoblastic interaction (coupling). The sequence variation, 713-8delC in the TGF-beta1 gene has previously been found to be associated with very low bone mass in osteoporotic women and with increased bone turnover in both osteoporotic and normal women. The possible association of this polymorphism with bone mass and bone turnover has now been investigated in 256 postmenopausal Italian women. A significant association of TGF-beta1 with bone mass was detected in the populations. Subjects carrying the sequence variation 713-8delC (Tt) genotype showed a significantly lower bone mineral density (BMD) at the hip than those without sequence variation in the genotype (TT). Individuals carrying the tt genotype have a more severe osteoporosis (P=0.0001 vs. TT and Tt genotypes). The frequency of the fragility fractures was significantly lower in individuals with TT genotype than in those with the Tt and tt genotypes (X2=21.9; P=0.006). Furthermore a significant association was found between 713-8delC and bone turnover. The results suggest a strong evidence for an association among the 713-8delC allele of the TGF-beta1 gene and the femoral BMD, the prevalence of osteoporotic fractures, and finally a high bone turnover in a sample of Italian postmenopausal women.     

Interaction of interleukin-6 and estrogen receptor gene polymorphisms on bone mass accrual in Chinese adolescent girls

We assessed the main and interaction effects of interleukin-6 and estrogen receptor gene polymorphisms on bone mass accrual in Chinese adolescent girls. A total of 228 premenarche Chinese girls (9-11.5 years old) were recruited for a 2-year follow-up study. Bone mineral density (BMD) at the total body, lumbar spine (L1-L4), and total left hip were measured by dual-energy X-ray absorptiometry at baseline and follow-up. The -174G/C and -634C/G polymorphism of IL-6 gene, and PvuII and XbaI polymorphisms of the estrogen receptor (ER)-alpha gene, were determined. The -634C/G polymorphism of the IL-6 gene and PvuII polymorphism of ER-alpha gene were significantly associated with bone mass accrual after adjusting the potential confounding factors. Girls with pp genotype of ER-alpha gene had greater percentage accrual in BMD of total body (P = 0.010) and femoral intertrochanter (P = 0.038) than their PP and Pp counterparts. Girls with CC genotype of IL-6 -634G/C gene had higher percentage accrual in BMD of total body (P = 0.032) and femoral trochanter (P = 0.048) than their CG + GG counterparts. Significant interaction effects of IL-6 -634C/G polymorphism and ER-alpha PvuII polymorphism were observed on percentage change in BMD of total left hip (P = 0.009) and femoral intertrochanter (P = 0.007). The genotype CC (IL-6 -634C/G) x pp (ER-alpha PvuII) was associated with greater BMD accrual than other genotype combination in Chinese adolescent girls. We found that the IL-6 -634C/G and ER-alpha PvuII polymorphism were significantly associated with BMD accrual and that they have an interactional effect on BMD accrual in Chinese adolescent girls.     

Calcium-Sensing Receptor Gene Polymorphism A986S Does Not Predict Serum Calcium Level, Bone Mineral Density, Calcaneal Ultrasound Indices, or Fracture Rate in a Large Cohort of Elderly Women

Postmenopausal osteoporosis is a complex and heterogeneous disease influenced by multiple factors and related to peak bone mass achieved in early adult life, followed by a subsequent continuous bone loss. Genetic variance and polymorphisms have been shown to be of clinical significance for osteoporotic fragility fractures. Previous studies have related variations in the calcium sensor receptor (CASR) gene to circulating Ca levels and bone mass in young women and adolescent girls. The aim of this study was to investigate the impact of the A986S polymorphism of the CASR gene on calcium homeostasis and bone metabolism in elderly women. We studied the distribution of the A986S polymorphism in a large cohort of 1252 ambulatory Australian women in relation to biochemical markers of bone metabolism, bone mass evaluated by quantitative ultrasound measurements (QUS) and DXA of the hip, prevalent and 36-month incident fracture data. No effect of the polymorphism was found on circulating calcium level, renal Ca excretion, or biochemical markers of bone turnover. Moreover, A986S was not associated with bone mass or prevalent or incident fractures. Power calculations revealed that a difference in circulating calcium levels of 0.05 mmol/l, a difference in DXA bone density of 24 mg, and a 1.6-fold difference in fracture rate could have been detected with a power of 80%. In conclusion, in a large cohort of elderly women the A986S polymorphism of the CASR gene was not found to be significant for calcium homeostasis or bone mass. It is questioned whether the polymorphism has any clinical significance for postmenopausal osteoporosis.     

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 of Bone Mineral Density with Polymorphism of the Human Calcium-Sensing Receptor Locus

A strong correlation between bone mass and genetic factors has been shown in twins and family studies. Some of the genes involved would regulate bone metabolism, bone formation, and resorption, all processes that determine bone mass. One candidate genes, calcium-sensing receptor (CASR) in the parathyroid gland, regulates calcium homeostasis by sensing decreases in extracellular calcium level and effecting an increase in secretion of parathyroid hormone (PTH) and calcium (Ca) reabsorption in the kidney. We have investigated a possible association between the CA-repeat polymorphism at the human CASR gene locus and the bone mineral density (BMD) of radial bone in 472 postmenopausal Japanese women. Genotypes were classified into nine groups according to the number of CA repeats present, from 20 to 12. BMD was expressed as the adjusted BMD, which was the body mass index (BMI), and age-adjusted average BMD. The 247 women who had an A3 allele (228 bp, containing 18 repeats of CA) had significantly lower adjusted BMD (mean ± SD: 0.303 ± 0.059 versus 0.316 ± 0.063 g/cm²; P= 0.0308) than the participants (n = 201) who did not carry an allele of that size. This result suggests that genetic variation at the CASR gene locus is associated with some determinants for BMD in postmenopausal women. Received: 3 November 1998 / Accepted: 29 September 1999     

A common methylenetetrahydrofolate reductase (C677T) polymorphism is associated with low bone mineral density and increased fracture incidence after menopause: longitudinal data from the Danish osteoporosis prevention study.

A polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR) has recently been associated with bone mineral density (BMD) in postmenopausal Japanese women. It is not known whether this effect is also present in European populations and whether it is caused by lower peak bone mass or accelerated postmenopausal bone loss. MTHFR genotyping was done in 1748 healthy postmenopausal Danish women participating in a prospective study of risk factors for osteoporosis. At the time of enrollment, 3-24 months after last menstrual period, the less prevalent genotype (TT, 8.7% of the population) was associated with significantly lower BMD at the femoral neck (ANOVA, p < 0.05), total hip (p < 0.01), and spine (p < 0.05 adjusted for lifestyle covariates, p = 0.06 without adjustment). The mean difference was between 0.1 and 0.3 SD, depending on measurement site. MTHFR genotype added significantly to prediction of BMD by weight and age. Fracture incidence was increased more than 2-fold in subjects with the TT genotype (risk ratio [RR], 2.6; 95% CI 1.2-5.6). This remained significant when the Cox analysis was controlled for BMD (RR, 2.4; 95% CI 1.1-5.2). No differences in serum osteocalcin, bone-specific alkaline phosphatase, and 25-OH-vitamin D were found between genotypes. The response to hormone replacement therapy (HRT) did not differ, but the association of the TT genotype with reduced BMD was maintained at the total hip after 5 years of HRT. The MTHFR TT genotype is associated with low BMD and increased fracture incidence in early postmenopausal women.     

Association of Transforming Growth Factor-b1 (TGFb1) T29?C Gene Polymorphism with Bone Mineral Density (BMD), Changes in BMD, and Serum Concentrations of TGF-b1 in a Population-Based Sample of Postmenopausal German Women

TGF-beta1 is thought to play an important role in bone turnover. Thus, the gene encoding TGF-beta1 is a prime candidate for the genetic regulation of bone density. Recent studies have suggested that a T29 --> C polymorphism in the signal sequence region of the TGF-beta1 gene may be related to bone mineral density (BMD) and bone loss in postmenopausal Japanese women. In the present study, we examined the relationship between this polymorphism and BMD in a population-based sample of 102 estrogen-deficient postmenopausal women from the Heidelberg cohort of the European Vertebral Osteoporosis Study (EVOS). Average BMD in women with the TT genotype was approximately 10% higher at both the lumbar spine and the femoral neck compared with women with the CC genotype (spine: 980 vs. 887 mg/cm2, P = 0.05; femoral neck: 755 vs. 674 mg/cm2; P = 0.02). Women with the TT genotype also experienced less overall bone loss at the total hip, compared with women with the CC genotype. Serum levels of TGF-beta1 were higher in women with the TT genotype than in those with the CC genotype (46.5 ng/ml vs. 32.3 ng/ml, P = 0.001). These data are clearly in contrast to findings in postmenopausal Japanese women where the CC genotype was associated with higher BMD and decreased bone loss. Further studies are therefore necessary to clarify the relationship between this polymorphism and BMD.     

The BsmI vitamin D receptor gene polymorphism in Israeli populations and in perimenopausal and osteoporotic Ashkenazi women.

BACKGROUND: The association between vitamin D receptor (VDR) gene polymorphisms and bone mineral density (BMD) is controversial, and may be effected by ethnic ancestry and age. AIMS: To determine the distribution of the BsmI VDR gene polymorphism in healthy Israeli populations, and to study its association with BMD in perimenopausal and osteoporotic Ashkenazi women. METHODS: Allele and genotype frequencies of the VDR gene defined by BsmI restriction site were determined in 634 healthy Israelis of seven ethnic groups, 90 Ashkenazi perimenopausal women and in 75 Ashkenazi osteoporotic women. Genotype-related differences in spinal and femoral neck BMD were determined in Ashkenazi perimenopausal women. Allele and genotype frequencies in Ashkenazi osteoporotic women were compared with Ashkenazi controls. RESULTS: The frequency of the BB genotype was higher in Yemenites compared with Ashkenazi and Libyan Jews (23, 11 and 8%, respectively, p < 0.05), and lower in Ashkenazi compared with Iraqi and Persian Jews (11, 20 and 21%, respectively, p = 0.05). BMD did not vary by genotype in perimenopausal women, nor were there differences in the frequencies of the B allele or the BB genotype in osteoporotic women compared with controls. CONCLUSIONS: There is ethnic variability in the frequency of the BsmI VDR gene polymorphism. In Ashkenazi perimenopausal and osteoporotic women this polymorphism is not associated with BMD.     

Polymorphism at an Sp1 Binding Site of COL1A1 and Bone Mineral Density in Premenopausal Female Twins and Elderly Fracture Patients

Polymorphism at an Sp1 binding site in the COL1A1 gene has been reported to be associated with bone mineral density (BMD) and osteoporotic vertebral fracture. We therefore examined for associations and linkage of the Sp1 polymorphism in the COL1A1 gene and BMD at the lumbar spine and femoral neck in 38 monozygotic (MZ) and 40 dizygotic (DZ) twin pairs of white adult women. All twins were premenopausal with an age range of 21–49 years. Sp1 genotypes of 56 patients with idiopathic osteoporotic vertebral fracture were examined for a preponderance of either genotype relative to our normal healthy twin subjects. In the twin sample no significant association was found between Sp1 genotypes and BMD at the spine and femoral neck. No linkage of Sp1 genotype and BMD at the spine or femoral neck was observed in DZ twins discordant for genotype. Frequencies of Sp1 genotypes were similar in our healthy (twin) and fracture population samples. In conclusion, in our American sample of premenopausal twins we found no association or linkage of the Sp1 polymorphism at the COL1A1 gene and BMD at the lumbar spine and femoral neck, and no over-representation of any Sp1 genotype was observed in our sample of patients with osteoporotic vertebral fracture. Taken together these results indicate that the Sp1 polymorphism is not related to BMD in our American sample, and contrasts with the findings in a British population. Received: 16 November 1997 / Accepted: 12 June 1998     

FSHR基因多态性与绝经后骨质疏松症的关联性分析

目的探讨卵泡刺激素受体(FSHR)中外显子10多态性与绝经后骨质疏松症的相关性。方法选取2017年8月至2019年3月因骨质疏松于本院骨科住院的136例绝经后女性患者为研究对象(骨质疏松组),同期选取118例绝经后非骨质疏松女性作为对照(对照组)。提取两组女性外周血基因组DNA,采用PCR法扩增FSHR基因外显子10的片段并进行基因测序,探究其基因多态性。结果两组年龄、绝经期年龄、绝经期年限、糖尿病患病比例、高血压患病比例、糖化血红蛋白(Hb A1c)、空腹胰岛素(FINS)比较,差异无统计学意义(P0.05);骨质疏松组抗酒石酸酸性磷酸酶-5b(TRACP-5b)、血清骨碱性磷酸酶(BALP)水平显著高于对照组,体质量指数(BMI)、腰椎骨密度(BMD)、股骨颈BMD水平显著低于对照组,差异有统计学意义(P0.05); FSHR在基因外显子10的680多态位点上有A/A型、A/S型、S/S型3种基因型,对照组基因型中A/A型(占62.71%)最多,其次为A/S型(占20.33%),S/S型(占16.96%)最少;骨质疏松组基因型中以S/S型(占59.56%)为主,其次为A/A型(占28.68%),A/S型(占11.76%)最少,两组基因型比较,差异均有统计学意义(P0.05); S/S型基因型、BMI是影响骨质疏松发生的独立危险因素,腰椎L2-L4 BMD、股骨颈BMD是影响骨质疏松发生的保护因素(P0.05)。结论FSHR基因多态性与绝经后骨质疏松症有一定相关性,其中S/S型基因型在绝经后骨质疏松患者中出现频率较高,可能与绝经后骨质疏松发生发展有关。     

Bone mineral density and total body bone mineral content in 18- to 22-year-old women

One hundred sixty-four (164) healthy, young Caucasian women enrolled as midshipmen at the United States Naval Academy with no known disease or bone injury were followed for 3.6 years. Change in bone mineral density (BMD) of the hip, lumbar spine and distal tibia, and total body bone mineral content (TBMC) was measured by dual energy X-ray absorptiometry (DXA). Bone mineral density and TBMC of these women were measured within 2 months (60 ± 4 days) of entering the Academy and annually. Over the study period, hip BMD increased 2.26% (P < 0.001), lumbar spine BMD increased 3.27% (P < 0.001) and distal tibia BMD increased 5.2% (P < 0.001). Total body bone mineral content showed a 5.25% (P < 0.001) increase during the study period. In this group of young women, gain in BMD and TBMC continued until age 22. These results suggest that bone mass may accrue in certain groups of women beyond age 22. The significance of this increase in bone mass during early adulthood on risk for osteoporotic fractures in later life and its impact on exercise-related bone injuries are unknown and warrant further examination.     

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.     

Relationship among VDR (BsmI and FokI), COLIA1, and CTR polymorphisms with bone mass,bone turnover markers,and sex hormones in men

Osteoporosis is a disease characterized by low bone mineral density (BMD) and up to 80% of its variance is under genetic control. Although osteoporosis is more frequent in women, one-third of hip fractures also occur in men. Much information on genetic factors and bone density has been obtained in women, but only a few studies have been performed in osteoporotic men. We have evaluated the relationship between polymorphisms for several candidate genes such as vitamin D receptor (VDR), collagen type Ia1 (COLIA1), and calcitonin receptor (CTR) in a sample of unrelated Italian men (n = 253, mean age 58.41 +/- 15.64 SD). We found no significant differences in BMD when subjects were stratified for their VDR (BsmI and FokI) and COLIA1 genotypes. BMD both at the lumbar spine and at the femoral neck were associated with polymorphism of CTR gene. The CC genotype of CTR gene had the lowest BMD value (P <0.05 and P <0.01 at the spine and hip, respectively) and its prevalence was significantly over-represented in the subgroup of men with prior hip or vertebral fracture as compared with controls (P = 0.004% c2 = 11.10). The men with the CC genotype also showed significantly lower body mass index (BMI), serum sex hormone binding globulin (SHBG), estradiol, total alkaline phosphatase-(total AP) and bone alkaline phosphatase (bone AP) levels and significantly higher free androgen index (FAI). In conclusion, the polymorphism of CTR gene but not VDR and COLIA1 is associated with osteoporosis incidence and the levels of alkaline phosphatase and estradiol. The lower BMD in CC genotype is apparently associated in males with depressed bone formation and lower estradiol levels.