Non-association of estrogen receptor genotypes with bone mineral density and bone turnover in Korean pre-, peri-, and postmenopausal 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.

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.

Association between dietary phytoestrogen intake and bone mineral density varied with estrogen receptor alpha gene polymorphisms in southern Chinese postmenopausal women

INTRODUCTION

several studies have investigated the relationship between the estrogen receptor (ER) gene polymorphisms and the efficacy of estrogen replacement therapy in postmenopausal osteoporosis. However, the association of ER polymorphisms with the effects of dietary phytoestrogens on bone metabolism has not yet been reported. This study explores the possibility that ER alpha subtype (ERα) gene polymorphisms are involved in the effects of dietary phytoestrogens on bone mineral density (BMD) in postmenopausal women.

METHODS

a total of 301 postmenopausal southern Chinese women were enrolled. Dietary phytoestrogen intake was evaluated using a food frequency questionnaire. ERα polymorphisms were examined with restriction fragment length polymorphism at the polymorphic PvuII and XbaI sites within intron 1. Dual-energy X-ray absorptiometry scans were performed to determine the BMD of the lumbar spine and hip.

RESULTS

the positive association of the lumbar spine BMD with dietary phytoestrogen intake was maintained only in groups with pp or xx genotypes (p < 0.05) and disappeared in groups with other genotypes. A positive association of the hip BMD with dietary phytoestrogen intake was observed only in the xx genotype group (p < 0.05).

CONCLUSIONS

the association of the dietary phytoestrogen intake and BMD in southern Chinese postmenopausal women varied with ERα gene polymorphisms.

Influence of estrogen receptor α polymorphisms on bone density in response to habitual exercise in Japanese postmenopausal women

Estrogen receptor α (ER α) is one of candidate genes for osteoporosis. This study examined the influence of ER α gene, PvuII, and XbaI genotypes on bone density of calcaneus in response to habitual exercise. ER α polymorphisms were detected using PvuII and XbaI restriction enzymes in 316 Japanese postmenopausal women. The bone density was significantly lower in the women carrying PP, pp, or xx genotype without habitual exercise than in the age-matched women without those genotypes. The women carrying Pp genotype without habitual exercise had normal bone density compared to those without Pp genotype. The women carrying PPxx or ppxx polymorphism without habitual exercise had low bone density compared to those with habitual exercise. Thus, the reduction of bone density was attenuated in the women carrying PPxx or ppxx with habitual exercise. In addition, habitual exercise was highly effective for the bone density in the women carrying xx homozygote. These findings indicate that analyses of XbaI and PvuII polymorphisms of ER α may be useful to predict the effect of exercise on bone density, and habitual exercise attenuates the reduction of bone density in women with some genotypes.

Genetic polymorphims of estrogen receptor alpha -397 PvuII (T>C) and -351 XbaI (A>G) in a portuguese population: prevalence and relation with breast cancer susceptibility

Estrogen receptor alpha (ERα), that mediates the biologic effects of estrogen in estrogen-sensitive tissues like breast, is genetically polymorphic. To evaluate the association between -397 PvuII (T>C) and -351 XbaI (A>G) restriction fragment length polymorphisms (RFLPs) in intron 1 of ERα gene and susceptibility of breast cancer, we undertook a case-control study in BRCA1 185delAG and 5382insC/BRCA2 6174delT negative Portuguese women. The study population consisted of 107 patients with histological diagnosis of breast cancer and 121 women with no history of breast cancer. Genomic DNA was extracted from blood samples and genotyping analyses were performed by PCR-RFLP. XbaI polymorphism was associated with a significant reduced risk of breast cancer for carriers of the x allele in homozygozity (OR 0.178; 95% CI 0.070-0.456; P<0.001) or heterozigozity (OR 0.223; 95% CI 0.089-0.561; P=0.001). The PvuII polymorphism was associated with a non-significantly reduced risk. The combined analysis of PvuII and XbaI polymorphisms revealed none synergistic effect of the two genotypes, except for simultaneous carriers of pp and xx genotypes, that have a reduced risk of breast cancer (OR 0.226; 95% CI 0.049-1.035; P=0.044). The combination of PvuII and XbaI genotypes into haplotypes showed that carriers of two copies of the px (ppxx) haplotype had a reduced risk of breast cancer (OR 0.405; 95% CI 0.194-0.843; P=0.014), compared with PX (PPXX+PPXx+PpXX+PpXx) haplotypes. PvuII and XbaI polymorphisms were in linkage disequilibrium both in cases (D=0.044, r2=0.049, X2=5.216, P=0.022) and controls (D=0.090, r2=0.139, X2=16.819, P<0.001), but not in the entire sample population analyzed as a whole (D=0.087, r2=0.0076, X2=1.733, P=0.188). In conclusion, in this case-control study we found that ERα gene XbaI polymorphism may modify individual susceptibility for breast cancer in this population.

Prevalence of ERα-397 PvuII C/T, ERα-351 XbaI A/G and PGR PROGINS polymorphisms in Brazilian breast cancer-unaffected women

Polymorphisms of hormone receptor genes have been linked to modifications in reproductive factors and to an increased risk of breast cancer (BC). In the present study, we have determined the allelic and genotypic frequencies of the ERα-397 PvuII C/T, ERα-351 XbaI A/G and PGR PROGINS polymorphisms and investigated their relationship with mammographic density, body mass index (BMI) and other risk factors for BC. A consecutive and unselected sample of 750 Brazilian BC-unaffected women enrolled in a mammography screening program was recruited. The distribution of PGR PROGINS genotypic frequencies was 72.5, 25.5 and 2.0% for A1A1, A1A2 and A2A2, respectively, which was equivalent to that encountered in other studies with healthy women. The distribution of ERα genotypes was: ERα-397 PvuII C/T: 32.3% TT, 47.5% TC, and 20.2% CC; ERα-351 XbaI A/G: 46.3% AA, 41.7% AG and 12.0% GG. ERα haplotypes were 53.5% PX, 14.3% Px, 0.3% pX, and 32.0% px. These were significantly different from most previously published reports worldwide (P < 0.05). Overall, the PGR PROGINS genotypes A2A2 and A1A2 were associated with fatty and moderately fatty breast tissue. The same genotypes were also associated with a high BMI in postmenopausal women. In addition, the ERα-351 XbaI GG genotype was associated with menarche ≥12 years (P = 0.02). ERα and PGR polymorphisms have a phenotypic effect and may play an important role in BC risk determination. Finally, if confirmed in BC patients, these associations could have important implications for mammographic screening and strategies and may be helpful to identify women at higher risk for the disease.

Estrogen receptor gene polymorphisms in a group of postmenopausal Turkish women: association with bone mineral density

OBJECTIVE

To evaluate the frequency of the estrogen receptor (ER) gene PvuII and XbaI polymorphisms and their associations with bone mineral density (BMD) in a group of postmenopausal Turkish women.

DESIGN

A total of 125 healthy postmenopausal women and 125 premenopausal healthy young women as controls were included in the study. The PvuII and XbaI polymorphisms in the ER gene were studied by the polymerase chain reaction-restriction fragment length polymorphism method. The BMD of the lumbar vertebrae and femoral neck were measured by dual-energy X-ray absorptiometry.

RESULTS

The frequencies of the ERα PVuII genotypes PP, Pp and pp were 20%, 54.4% and 25.6% in premenopausal and 24.8%, 44.8% and 30.4% in postmenopausal women, respectively. The frequencies of the ER XbaI genotypes XX, Xx, xx were 16.8%, 48.8% and 34.4% in premenopausal and 16.8%, 48% and 35.2% in postmenopausal women, respectively. There was no difference in the frequencies of ER gene polymorphisms between premenopausal and postmenopausal women. BMD measurements were not different between ER PvuII and XbaI genotypes in premenopausal and postmenopausal women.

CONCLUSIONS

ER gene PvuII and XbaI polymorphisms have no major influence on bone mineral density in our group of postmenopausal women.

Genetics of osteoporosis

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

Association of estrogen receptor alpha gene polymorphisms with BMD and their affect on estradiol levels in pre- and postmenopausal women in south Indian population from Andhra Pradesh

BACKGROUND

Osteoporosis is a multifactorial disorder with a strong genetic component and ESR1 is suggested as a candidate gene for osteoporosis. Therefore the present study is aimed to investigate the role of ESR1 gene polymorphisms and its influence on estradiol levels and BMD in osteoporotic women of Indian ethnicity.

METHODS

Four-hundred twenty-seven osteoporotic women and 460 age matched controls were included in the study. ESR1 gene polymorphism was assessed by PCR-RFLP method. Serum estradiol was measured by ELISA.

RESULTS

The frequency of pp and xx genotypes as well as p and x alleles was significantly high in pre- and postmenopausal osteoporotics when compared to controls (p<0.001). They had low BMD and estradiol levels in comparison with PP and XX genotype individuals (p<0.05).

CONCLUSION

The ESR1 gene is associated with low bone mass and low estradiol levels in all our study subjects. It is likely that the allele exerts its influence on the bone in early adulthood leading to an increased risk of osteoporosis later in life.

Association of estrogen receptor-alpha gene Pvull polymorphisms with the effect of calcium supplementation on skeletal development in Chinese pubertal girls

OBJECTIVE

To investigate the association of estrogen receptor alpha (ER-alpha) PvuII polymorphisms with the effect of calcium supplementation on bone development in Chinese pubertal girls, and to study the importance of calcium supplementation by maximizing the peak bone mass at their pubertal stage for bone development and osteoporosis prevention and the role of estrogen in regulating bone mass.

METHODS

Ninety-four pubertal girls were recruited in the study and divided into two groups and three sub-groups according to the ER-alpha PvuII polymorphisms. One year before and after calcium supplementation, bone mineral density (BMD) was measured by DEXA, while BGP, BAP, TRACP5b, and 25-OH-VitD(3), as well as estrogen were detected by ELISA. Analysis of covariance was used to examine the effect of ER-alpha polymorphisms on bone development.

RESULTS

The absolute increase and percentage change of BGP were significantly higher in the supplemented group than in the control group (P<0.05). In the intervened group, The increase and percentage change of the total body and radio distal 1/3 BMD were higher in PP than in PP genotype (P<0.05), and the increase of BAP in Pp was also higher than PP in the same group (P<0.05).

CONCLUSION

PP genotype shows a better response to calcium supplementation than the other PvuII polymorphisms.

The bone mass density in postmenopausal women using hormonal replacement therapy in relation to polymorphism in vitamin D receptor and estrogen receptor genes

The aims of the study were as follows: (1) To identify the differences in spinal body mass density (BMD) in relation to polymorphism in vitamin D receptor (VDR) and estrogen receptor-alpha (ERalpha) genes in untreated women with postmenopausal osteoporosis. (2) To assess the efficacy of treatment in women with postmenopausal osteoporosis in relation to polymorphism in VDR and ERalpha genes. (3) To find the estradiol concentration necessary to protect bone tissue in patients with a given polymorphism in VDR and ERalpha genes.

METHODS

The study included 44 postmenopausal women with primary osteoporosis who used cyclic hormonal replacement therapy (HRT) for a year. The polymorphism of ERalpha and VDR genes were evaluated. We also determined the age, body mass index and spinal BMD before and after 12 months of administration the HRT.

RESULTS

We found a significant spinal BMD increase, what is connected with ERalpha genotype and both VDR and ERalpha genes. There is no such a correlation observed in polymorphism of VDR gene.

CONCLUSIONS

(1) There is no relationship between VDR and ERalpha genes polymorphism and the stage of osteoporosis related to the spinal BMD value before treatment. (2) The XX, PP or Bb markers or only X, P, B alleles are connected with a significant decrease of treatment efficacy. (3) Estradiol serum concentration before and during HRT is not dependent on the polymorphism of VDR and ERalpha genes.

Estrogen receptor alpha CA dinucleotide repeat polymorphism is associated with rate of bone loss in perimenopausal women and bone mineral density and risk of osteoporotic fractures in postmenopausal women

The association between a newly identified CA repeat polymorphism of the estrogen receptor alpha gene (ESR1) with osteoporosis was investigated. Postmenopausal women with <18 CA repeats had low BMD, increased rate of bone loss and increased fracture risk.

INTRODUCTION

Studies have shown that intronic dinucleotide repeat polymorphisms in some genes are associated with disease risk by modulating mRNA splicing efficiency. D6S440 is a newly identified intronic CA repeat polymorphism located downstream of the 5'-splicing site of exon 5 of ESR1.

METHODS

The associations of D6S440 with bone mineral density (BMD), rate of bone loss and fracture risk were evaluated in 452 pre-, 110 peri- and 622 postmenopausal southern Chinese women using regression models.

RESULTS

Post- but not premenopausal women with less CA repeats had lower spine and hip BMD. The number of CA repeats was linearly related to hip BMD in postmenopausal women (beta=0.008; p=0.004). Postmenopausal women with CA repeats <18 had higher risks of having osteoporosis (BMD T-score< -2.5 at the spine: OR 2.46, 95% CI 1.30-4.65; at the hip: OR 3.79(1.64-8.74)) and low trauma fractures (OR 2.31(1.29-4.14)) than those with >or= 18 repeats. Perimenopausal women with <18 CA repeats had significantly greater bone loss in 18 months at the hip than those with >or= 18 repeats (-1.96% vs. -1.61%, p = 0.029).

CONCLUSIONS

ESR1 CA repeat polymorphism is associated with BMD variation, rate of bone loss and fracture risk, and this may be a useful genetic marker for fracture risk assessment.

Relationship of volumetric bone mineral density and structural parameters with ERalpha gene polymorphisms

Bone mineral density (BMD) contributes to bone strength, and methods for clinical assessment of bone quality characteristics beyond what can be gathered by BMD are awaited. Peripheral quantitative computed tomography (pQCT) allows for separate assessments of cortical and trabecular bone, providing information on bone geometry. Previous studies examining the relationship between estrogen receptor alpha (ERalpha) gene polymorphisms and BMD have been performed in large populations. However, only limited information is available on the possible segregation of ERalpha gene polymorphisms with bone structural properties. The aim of our study was to evaluate the association of XbaI and PvuII ERalpha gene polymorphisms with QCT parameters. We studied 900 subjects (541 women, 449 men) participating to the InCHIANTI study. By tibial pQCT we evaluated trabecular volumetric BMD, cortical volumetric BMD, cortical bone area, and cortical thickness (CtTh). Subjects were genotyped for ERalpha gene PvuII and XbaI polymorphisms. Analysis of variance was used for statistical analysis. Male subjects with PP and XX genotypes had higher geometric parameters, and female subjects with XX and PP genotypes showed higher densitometric parameters than other genotypes; however, the differences did not reach statistical significance. After adjustment for potential confounders, we found a significant (P = 0.002) CtTh difference across PvuII polymorphism in male subjects, with higher CtTh values in PP genotypes with respect to Pp and pp genotypes. These results show a relationship between the presence of the P allele and higher values of CtTh in male subjects, indicating for ERalpha a role in the control of tibial bone geometry.

The association of bone mineral density with estrogen receptor gene polymorphisms

The purpose of this investigation was to evaluate single nucleotide polymorphism (SNP) variants of the estrogen receptor genes ESR1 and ESR2 and bone mineral density (BMD) of the lumbar spine (LS-BMD) or total hip (hip BMD) in women of 4 races/ethnicities who were premenopausal or in early perimenopause. The sample consisted of 1,301 participants from the Study of Women's Health Across the Nation (SWAN) with measures of BMD and genotyping; of these, 295 were African American, 693 were Caucasian, 151 were Chinese, and 162 were Japanese. We evaluated the potential association of LS-BMD or hip BMD with 4 SNPs from the ESR1 gene (ESR1 rs9340799, ESR1 rs2234693, ESR1 rs728524, and ESR1 rs3798577), and 3 SNPs from the ESR2 gene (ESR2 rs1255998, ESR2 rs1256030, and ESR2 rs1256065). Unadjusted mean LS-BMD values ranged from 1.141+/-0.14 g/cm(2) in African American women to 1.031+/-0.11 g/cm2 in Japanese women; unadjusted mean hip BMD values ranged from 1.053+/-0.14 g/cm2 in African American women to 0.862+/-0.10 g/cm2 in Chinese women. African American and Japanese women with the ESR1 rs2234693 (PvuII) CC genotype had higher LS-BMDs than did their peers with the TT genotype (P=0.009 and P=0.04, respectively). Japanese women with the ESR1 rs3798577 CC or TC genotypes had lower LS-BMD than did Japanese women with the TT genotype (P=0.02 and P=0.01, respectively). Caucasian women with the TC genotype for ESR2 rs1256030 had lower LS-BMDs than did those with the CC genotype (P=0.02). Chinese women who were heterozygous for ESR2 rs1256030 or ESR2 rs1256065 had significantly higher LS-BMDs and hip BMDs than did the referent groups for each of these SNPs (CC and AA, respectively). Associations between BMD and ESR1 and ESR2 genotypes varied by race/ethnicity and by bone site. Our results differ from those previously reported for 2 ESR1 genotypes (ESR1 rs2234693 [PvuII] and ESR1 rs9340799 [XbaI]). Moreover, 2 ESR1 and 3 ESR2 SNPs we studied have not previously been examined with respect to BMD. Among these, ESR2 rs1256030 and ESR2 rs1256065 appear to have an effect at both the lumbar spine and hip in Chinese women and may warrant further study.

Association of estrogen receptor gene polymorphisms with susceptibility to adolescent idiopathic scoliosis

STUDY DESIGN

A case-control study is presented.

OBJECTIVE

To investigate the association of estrogen receptor gene polymorphisms with adolescent idiopathic scoliosis (AIS) risk.

SUMMARY OF BACKGROUND DATA

Previous studies have shown that genetic factors are important in the pathogenesis of idiopathic scoliosis. Only 1 publication suggested that XbaI site polymorphism was associated with curve severity of idiopathic scoliosis. However, to our knowledge, the relationship of estrogen receptor gene polymorphisms and the individual susceptibility to idiopathic scoliosis has not been studied.

METHODS

This study included 202 patients with AIS and 174 healthy controls. Height, menarche status, curve pattern, Cobb angle, and Risser sign in female patients were recorded. There were 2 polymorphic loci, PvuII and XbaI locus, of estrogen receptor analyzed by restriction fragment length polymorphisms.

RESULTS

The frequency of XX genotype was significantly higher in patients than that in controls (P = 0.005). The X allele appeared to be overrepresented in patients compared with controls (P = 0.001). Furthermore, the frequencies of XX genotype in female patients whose height was > or = 160 cm and Cobb angle > or = 40 degrees were higher than those whose height was <160 cm and Cobb angle <40 degrees (P = 0.001 and P < 0.001, respectively).

CONCLUSIONS

The XbaI site polymorphism of estrogen receptor gene may be associated with a risk of AIS.

Association of oestrogen receptor alpha gene polymorphisms with postmenopausal bone loss, bone mass, and quantitative ultrasound properties of bone

BACKGROUND

The gene encoding oestrogen receptor alpha (ESR1) appears to regulate bone mineral density (BMD) and other determinants of osteoporotic fracture risk.

OBJECTIVE

To investigate the relation between common polymorphisms and haplotypes of the ESR1 gene and osteoporosis related phenotypes in a population based cohort of 3054 Scottish women.

RESULTS

There was a significant association between a common haplotype "px", defined by the PvuII and XbaI restriction fragment length polymorphisms within intron 1 of the ESR1 gene, and femoral neck bone loss in postmenopausal women who had not received hormone replacement therapy (n = 945; p = 0.009). Annual rates of femoral neck bone loss were approximately 14% higher in subjects who carried one copy of px and 22% higher in those who carried two copies, compared with those who did not carry the px haplotype. The px haplotype was associated with lower femoral neck BMD in the postmenopausal women (p = 0.02), and with reduced calcaneal broadband ultrasound attenuation (BUA) values in the whole study population (p = 0.005). There was no association between a TA repeat polymorphism in the ESR1 promoter and any phenotype studied, though on long range haplotype analysis subjects with a smaller number of TA repeats who also carried the px haplotype had reduced BUA values.

CONCLUSIONS

The ESR1px haplotype is associated with reduced hip BMD values and increased rates of femoral neck bone loss in postmenopausal women. An association with BUA may explain the fact that ESR1 intron 1 alleles predict osteoporotic fractures by a mechanism partly independent of differences in BMD.

Estrogen receptor alpha gene polymorphisms are associated with changes in bone remodeling markers and treatment response to estrogen

OBJECTIVES

Association studies between estrogen receptor alpha (ERalpha) gene polymorphisms and bone mineral density (BMD) have yielded inconsistent results. In the present study we evaluated the influence of XbaI and PvuII ERalpha gene polymorphisms on BMD, biochemical markers, rates of bone loss and the response to estrogen/hormone therapy (ET/HT) in elderly postmenopausal women.

METHODS

At baseline, we measured the association between ERalpha genotypes and BMD and biochemical markers in 489 elderly women, mean age 71 +/- 3 years. In the longitudinal study, the changes in the same measures were determined in 96 women on placebo and in 79 women receiving the ET/HT for 3 years. The XbaI and PvuII ERalpha polymorphisms were determined by polymerase chain reaction (PCR). BMD measurements for spine, femoral neck and total body were performed by DEXA, and biochemical indices were measured by standard methods.

RESULTS

Neither the PvuII nor the XbaI ERalpha gene polymorphisms were associated with baseline BMD and biochemical indices. In the longitudinal study, there were trends for higher bone loss in the placebo group in the genotypes pp or xx compared to PP or XX genotypes, but the changes were not significant. However, the changes in the bone markers were significantly (p < 0.05) higher in genotype group pp compared to PP (serum osteocalcin, 4.9 +/- 7.0% versus -13.4 +/- 6.7%; urine NTx:Cr ratio, 32.3+/-10.3% versus -2.5 +/- 10.3%) or xx compared to XX (serum osteocalcin, 7.5 +/- 6.4% versus -15.6+/-7.3%; urine NTx:Cr ratio, 39.4 +/- 9.2% versus -8.84+/-10.7%). At the end of 3 years, the mean urine NTx:Cr ratio was 78.7 +/- 9.0 versus 44.6 +/- 4.9 in pp versus PP (p < 0.05) and 75.5 +/- 10.7 versus 48.7 +/- 5.4 in xx versus XX (p < 0.05) genotypes. The response in total body BMD to ET/HT treatment was significantly higher in women with the PP genotype compared to pp genotype (2.48 +/- 0.55% versus 0.66 +/- 0.46%). Similar trends were seen at other skeletal sites for both XX and PP compared to pp and xx genotypes.

CONCLUSION

Women with ERalpha, PP and XX genotypes have lower bone remodeling, lower rates of bone loss and benefit more from hormone therapy.

Association of estrogen receptor alpha gene polymorphisms with bone mineral density in postmenopausal Indian women

Bone mineral density (BMD) is the major determinant of osteoporotic fracture risk with a particular genetic background. However, consensus on the association of BMD with specific gene locus has not been reached. In the present study, we investigated the potential association of estrogen receptor alpha (ER alpha) gene intron I polymorphisms with BMD in 246 postmenopausal Indian women (average age 54.2+/-3.4 years). All the subjects were genotyped for XbaI and PvuII polymorphisms and underwent BMD measurements at spine and hip by dual energy X-ray absorptiometery. The average BMD of subjects with the genotypes XX and PP (absence of restriction sites for XbaI and PvuII, respectively) was 12.7 and 5.4% higher at the spine and 13.1 and 4.6% higher at the hip, respectively, than those with genotypes xx and pp. In age vs. BMD scatterplot, the intercept and slope of regression lines for genotypes xx and pp at spine and hip demonstrated comparatively rapid decrease in BMD across the age. The genotype XX was significantly prevalent (p<0.001) in women with normal bone mass (32%) and genotype xx in women with osteoporotic bone mass (35.3%), within the group. A significantly higher relative risk was associated with xx genotype. The study concludes that genetic variations at ER alpha gene locus, perhaps, are associated with BMD in Indian women and may influence some determinant of bone metabolism resulting in accelerated bone loss with age.

The relation of the XbaI and PvuII polymorphisms of the estrogen receptor gene and the CAG repeat polymorphism of the androgen receptor gene to peak bone mass and bone turnover rate among young healthy men

The genes coding for estrogen receptor-alpha (ER-alpha) and androgen receptors (AR) are potential candidates for the regulation of bone mass and turnover, which may contribute to both the achievement of peak bone mass and bone loss after completion of growth. The present study was aimed at elucidating the role of two restriction fragment lengths (XbaI and PvuII) polymorphisms of the ER gene and the CAG repeat polymorphism of the AR gene as determinants of peak bone mass in men; special attention was paid to the interaction between serum free estradiol (E2) levels and the XbaI and PvuII genotypes. A cross-sectional study, with data on lifestyle factors collected retrospectively, was performed in 234 young men, aged 18.3 to 20.6 years. Of the men, 184 were recruits of the Finnish Army and 50 were men of similar age who had postponed their military service for reasons not related to health. Bone mineral content (BMC), density (BMD) and scan area were measured in the lumbar spine and upper femur by dual-energy X-ray absorptiometry (DXA). The bone turnover rate was assessed by measuring serum type I procollagen aminoterminal propeptide (PINP) and tartrate-resistant acid phosphatase 5b (TRACP5b) as well as urinary excretion of type I collagen aminoterminal telopeptide (NTX). After adjusting for age, height, weight, exercise, smoking, calcium and alcohol intake, BMC, scan area and BMD at all measurement sites were similar for the different XbaI and PvuII genotypes of the ER and independent of the number of the CAG repeats of the AR gene. No association was found between free E2 levels and bone parameters among any genotype group of the XbaI and PvuII polymorphisms. Except for urinary NTX, which showed a tendency to higher values for the xx (P=0.08) and pp (P=0.10) genotypes of the ER, bone turnover markers were not related to the genotypes studied. Our study does not support the view that the XbaI and PvuII polymorphisms of the ER gene and the CAG polymorphism of the AR gene would have a substantial impact on the development of peak bone mass in young Finnish men.

Genetic polymorphisms of OPG, RANK, and ESR1 and bone mineral density in Korean postmenopausal women

To evaluate the effects of genetic polymorphisms of OPG, RANK, and ESR1, which regulate osteoclastogenesis, on bone mineral density (BMD), a cross-sectional study was conducted in 650 Korean postmenopausal women. BMDs of the distal radius and the calcaneus were measured by dual energy X-ray absorptiometry (DXA). Genetic polymorphisms of OPG 163 A > G, 1181 G > C; RANK 421 C > T, 575 T > C; and ESR1 1335 C > T, 2142 G > A were determined by matrix-assisted laser desorption/ionization-time of flight (MALDI-ToF) mass spectrometry. The differences between the BMDs of the genotypes of OPG, RANK, and ESR1 were analyzed by multiple linear regression model adjusted for age and body mass index. Women with the OPG 1181 CC genotype had higher BMDs at the distal radius (7%) and calcaneus (10%) than those with the GG genotype; and these differences were statistically significant (P = 0.001 and P = 0.007, respectively). A significant association was also observed between RANK 575 T > C and calcaneus BMD (P for trend = 0.017). No significant association was observed between BMDs and the polymorphisms of ESR1. The association between OPG 1181 G > C and BMD was profound in subjects with the RANK 575 TT or ESR1 2142 GG genotypes; women with OPG 1181 CC had higher BMDs at the distal radius (11%) and calcaneus (11%) than those with OPG 1181 GG only in women with RANK 575 TT genotype (P = 0.002 and P = 0.021, respectively). These results suggest that OPG genetic polymorphisms, especially with the RANK 575 TT or ESR1 2142 GG genotypes, are related to low BMD in postmenopausal Korean women.

Association between exercise and pubertal BMD is modulated by estrogen receptor alpha genotype

Genetic and environmental factors contribute to bone mass, but the ways they interact remain poorly understood. This study of 245 pre- and early pubertal girls found that the PvuII polymorphism in the ER-alpha gene modulates the effect of exercise on BMD at loaded bone sites.

INTRODUCTION

Impaired achievement of bone mass at puberty is an important risk factor for the development of osteoporosis in later life. Genetic, as well as environmental, factors contribute to bone mass, but the ways they interact with each other remain poorly understood.

MATERIALS AND METHODS

We investigated the interaction between a PvuII polymorphism at the ER-alpha gene and physical activity (PA) on the modulation of bone mass and geometry in 245 10- to 13-year-old pre- and early pubertal Finnish girls. Level of PA was assessed using a questionnaire. Bone properties were measured using DXA and pQCT. The analyses were controlled for the effects of Tanner stage and body size index.

RESULTS

Girls with heterozygote ER-alpha genotype (Pp) and high PA had significantly higher bone mass and BMD, as well as thicker cortex, at loaded bone sites than their low-PA counterparts. No differences were found in bone properties of the distal radius, which is not a weight-bearing bone. Bone properties did not differ in either homozygote groups (PP and pp) regardless of the PA level.

CONCLUSIONS

These findings suggest that the PvuII polymorphism in the ER-alpha gene may modulate the effect of exercise on BMD at loaded bone sites. The heterozygotes may benefit most from the effect of exercise, whereas neither of the homozygote groups received any significant improvement from high PA. Furthermore, high PA may hide the genetic influence on bone. Indeed, it seems that one may compensate one's less favorable Pp genotype by increasing leisure PA at early puberty.

The relationship of estrogen receptor-α polymorphism with symptoms and other characteristics in post-menopausal women

OBJECTIVES

To study the influence of the estrogen receptor-alpha (ER-alpha) genotypes (PvuII and XbaI polymorphisms) on symptoms and bone density.

METHODS

We recruited 177 post-menopausal women to register hot flashes, vaginal dryness, depression, anxiety, sleep alterations, and serum hormones (FSH, LH, estrone, and estradiol). Bone mineral density (BMD) was measured with a radiographic method, correcting with an external reference. ER-alpha genotyping was carried out by PCR.

RESULTS

Scores for vaginal dryness were lower for the xx (P = 0.003), and pp genotypes (P = 0.006). Hot flashes were lower for the Pp (P = 0.006) genotype. FSH circulating levels were lower for Xx genotype (P = 0.036). The factors associated with BMD were estrone (P > 0.000001), estradiol (P = 0.0035) and XbaI (P = 0.035). Vaginal dryness, was associated with PvuII and XbaI polymorphisms (P = 0.037 and P = 0.039). Depression was associated with log(estrone) (P = 0.011), schooling (negatively, P = 0.012), and marginally with BMI (P = 0.066). Sleep alterations correlated with log(estrone) (P = 0.014) and marginally with years since menopause (P = 0.046). Anxiety correlated with schooling (negatively, P = 0.006) and age (p = 0.015), and hot flashes with schooling (negatively, P = 0.014). BMD was associated with log(estrone) (p < 0.000001), estradiol (negatively, P = 0.0036), and marginally with XbaI (P = 0.036).

CONCLUSIONS

In post-menopausal women, the ER-alpha polymorphism was associated with vaginal dryness, and hot flashes but not with other physical or emotional symptoms. Extraglandular estrogen production, and diverse molecular factors related to estrogen action may play an important role in this process.

Interaction between vitamin D receptor genotype and estrogen receptor alpha genotype influences vertebral fracture risk

In view of the interactions of vitamin D and the estrogen endocrine system, we studied the combined influence of polymorphisms in the estrogen receptor (ER) alpha gene and the vitamin D receptor (VDR) gene on the susceptibility to osteoporotic vertebral fractures in 634 women aged 55 yr and older. Three VDR haplotypes (1, 2, and 3) of the BsmI, ApaI, and TaqI restriction fragment length polymorphisms and three ERalpha haplotypes (1, 2, and 3) of the PvuII and XbaI restriction fragment length polymorphisms were identified. We captured 131 nonvertebral and 85 vertebral fracture cases during a mean follow-up period of 7 yr. ERalpha haplotype 1 was dose-dependently associated with increased vertebral fracture risk (P < 0.001) corresponding to an odds ratio of 1.9 [95% confidence interval (CI), 0.9-4.1] per copy of the risk allele. VDR haplotype 1 was overrepresented in vertebral fracture cases. There was a significant interaction (P = 0.01) between ERalpha haplotype 1 and VDR haplotype 1 in determining vertebral fracture risk. The association of ERalpha haplotype 1 with vertebral fracture risk was only present in homozygous carriers of VDR haplotype 1. The risk of fracture was 2.5 (95% CI, 0.6-9.9) for heterozygous and 10.3 (95% CI, 2.7-40) for homozygous carriers of ERalpha haplotype 1. These associations were independent of bone mineral density. In conclusion, interaction between ERalpha and VDR gene polymorphisms leads to increased risk of osteoporotic vertebral fractures in women, largely independent of bone mineral density.

Estrogen receptor alpha gene polymorphisms and peak bone density in Chinese nuclear families

PBD is an important determinant of osteoporotic fractures. Few studies were performed to search for genes underlying PBD variation in Chinese populations. We tested linkage and/or association of the estrogen receptor alpha gene polymorphism with PBD in 401 Chinese nuclear families. This study suggests the ER-alpha gene may have some minor effects on PBM variation in the Chinese population. Low peak bone density (PBD) in adulthood is an important determinant of osteoporotic fractures in the elderly. PBD variation is mainly regulated by genetic factors. Extensive molecular genetics studies have been performed to search for genes underlying PBD variation, largely in whites. Few studies were performed in Chinese populations. In this study, we simultaneously test linkage and/or association of the estrogen receptor alpha (ER-alpha) gene polymorphism with PBD in 401 Chinese nuclear families (both parents plus their female children) of 1260 subjects, with the 458 children generally between 20 and 40 years of age. All the subjects were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) at polymorphic PvuII and XbaI sites inside the ER-alpha gene. Bone mineral density was measured at the lumbar spine (L1-L4) and hip (femoral neck, trochanter, and intertrochanteric region). Raw bone mineral density values were adjusted by age, height, and weight as covariates. We detected marginally significant results for within-family association (transmission disequilibrium; p = 0.054) between the spine bone mineral density variation and the ER-alpha XbaI genotypes. For the hip bone mineral density variation, significant (p < 0.05) linkage results were generally found for the two intragenic markers. Analyses of the haplotypes defined by the two markers confer further evidence for linkage of the ER-alpha with the hip PBD variation. In conclusion, this study suggests that the ER-alpha gene may have minor effects on PBD variation in our Chinese population.

Investigating the role of natural phyto-oestrogens on bone health in postmenopausal women

Research on the bone effects of natural phyto-oestrogens after menopause is at a relatively early stage. Published studies are few, difficult to compare and often inconclusive, due in part to design weaknesses. Currently, many questions remain to be answered including to what extent a safe daily intake may prevent postmenopausal bone loss. These questions can only be addressed by conducting well-planned, randomised clinical trials that take into consideration present knowledge in the oestrogen, phyto-oestrogen and bone fields. This review is intended to provide hints for critical decision-making about the selection of subjects, type of intervention, suitable outcome measures and variables that need to be controlled.

Hormone replacement therapy and menopause: a review of randomized, double-blind, placebo-controlled trials

Hormone replacement therapy (HRT) is frequently prescribed to healthy women to ameliorate menopausal symptoms. HRT is used long term (> or = 1 year) to prevent chronic disease in older women. The objective of this study was to review the benefits and risks of HRT and studies of menopause or HRT in Taiwan via a MEDLINE search. Recommendations are provided for future HRT research in Taiwan. Randomized, double-blind, placebo-controlled clinical trials are considered the gold standard of scientific evidence. A MEDLINE literature search (January 1966-July 2002) identified 23 papers on trials (> or = 1 year) that met the inclusion criteria. The results showed that various HRT regimens used for more than 1 year caused more harm than good in healthy menopausal women and that there was no benefit for women with coronary artery disease, Alzheimer's disease, hysterectomy, hysterosalpingo-oophorectomy, and ischemic stroke. None of this research was conducted in Taiwan. A MEDLINE search using the key words "estrogen replacement therapy and menopause in Taiwan" identified 16 studies. There was only one, short-term, HRT trial. No evidence suggested benefits from long-term HRT in menopausal women in Taiwan.

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.

ER-alpha variants and the cardiovascular effects of hormone replacement therapy

There is an accumulating body of evidence linking estrogen receptor-alpha (ER-alpha) gene polymorphisms with variation in cardiovascular risk factors or disease. The ER-alpha IVS1-397 T/C (PvuII), IVS1-351 A/C (XbaI) and the promoter region TA repeat polymorphisms have received the most attention. If ER-alpha genetic variants identify women at high risk for cardiovascular events, this information could be used to improve clinical decisions regarding the use of hormone replacement therapy (HRT). More detailed haplotype and genome-wide studies of many of the major HRT clinical trial cohorts are currently underway and these efforts promise to clarify many outstanding issues concerning estrogen action and cardiovascular disease.

Association of polymorphisms of the estrogen receptor alpha gene with bone mineral density and fracture risk in women: a meta-analysis

The contribution of genetic polymorphisms to bone mineral density (BMD) and fracture risk in women is a controversial topic. We evaluated the effect of the XbaI and PvuII polymorphisms of the estrogen receptor a to BMD and fracture risk in a meta-analysis, including published data and additional information from investigators. Five thousand eight hundred thirty-four women from 30 study groups were analyzed with fixed and random effects models. The PvuII polymorphism was not associated with BMD at any skeletal site examined and 95% CIs exclude effects over 0.015 g/cm2 for both the femoral neck and the lumbar spine. Conversely, XX homozygotes (women carrying two copies of the gene variant without an XbaI restriction site) consistently had higher BMD than other subjects. The magnitude of the effect was similar in the femoral neck and lumbar spine (0.014 g/cm2 [95% CI, 0.003-0.025] and 0.015 g/cm2 [95% CI, 0.000-0.030], respectively; no between-study heterogeneity for either). Total body BMD was also significantly higher in XX homozygotes (by 0.039 g/cm2 and 0.029 g/cm2 compared with Xx and xx, respectively). Available data on fractures suggested a protective effect for XX (odds ratio [OR], 0.66 [95% CI, 0.47-0.93] among 1591 women), but not PP (OR, 0.93 [95% CI, 0.72-1.18] among 2,229 women). In summary, we have found that XX homozygotes may have higher BMD and also a decreased risk of fractures when compared with carriers of the x allele, whereas the PvuII polymorphism is not associated with either BMD or fracture risk.

No major effect of estrogen receptor beta gene RsaI polymorphism on bone mineral density and response to alendronate therapy in postmenopausal osteoporosis

Genetic factors play an important role in the pathogenesis of osteoporosis. The genes involved are, however, still largely unknown. In the present study, we have investigated whether sequence variations in the estrogen receptor beta (ERbeta) gene are associated with bone mineral density (BMD) and biochemical markers of bone turnover in 79 Slovenian postmenopausal women with osteoporosis. We also assessed the response by BMD and bone markers to antiresorptive therapy with bisphosphonate alendronate. All eight exons of ERbeta gene were amplified by polymerase chain reaction and screened for mutations by single-strand conformation polymorphism analysis. Potentially mutated samples were found only in exon 5 and sequence analysis identified the presence of a silent mutation in codon 328 with a nucleotide substitution GTG to GTA. For easier detection of this silent mutation, the RsaI restriction fragment length polymorphism analysis was developed. The frequencies of genotypes were as follows: Rr 5.1% and RR 94.9%. Between both genotypes, no significant differences in baseline lumbar spine and femoral neck BMD or in bone markers osteocalcin and deoxypyridinoline were observed. Similarly, no significant difference between RR and Rr genotypes in BMD or bone markers after 1 year of therapy was found. The increase in lumbar spine BMD after therapy was the only parameter that approached statistical significance (P=0.099). Patients with genotype Rr showed a smaller increase compared to those with RR. Our results suggest that RsaI polymorphism of ERbeta gene is probably not an important genetic determinant of BMD and does not significantly influence the responsiveness to alendronate therapy.

Genetics of osteoporosis: role of steroid hormone receptor gene polymorphisms

Osteoporosis is a common skeletal disease characterized by low bone mass and microarchitectural deterioration of bone tissue with a consequent increase in bone fragility and susceptibility to fracture. In the past years, twin and family study have shown that this disease recognizes a strong genetic component and that genetic factors play an important role in regulating bone mineral density (BMD). While in few isolate conditions osteoporosis can be inherited in a simple Mendelian pattern, due to single gene mutations, in the majority of cases has to be considered a multifactorial polygenic disease in which genetic determinants are modulated by hormonal, environmental and nutritional factors. Given the important role that steroid hormones play in bone cell development and in the maintenance of normal bone architecture, polymorphisms at receptor of the steroid/thyroid hormone receptor superfamily, such as estrogen receptor alpha (ERalpha) and Vitamin D receptor (VDR) have been thoroughly investigated in the last years and appeared to represent important candidate genes. The individual contribution of these genetic polymorphisms to the pathogenesis of osteoporosis remains to be universally confirmed and an important aim in future work will be to define their functional molecular consequences and how these polymorphisms interact with each other and with the environment to cause the osteoporotic phenotype. A further promising application of genetic studies in osteoporosis comes from their pharmacogenomic implications, with the possibility to give a better guidance for therapeutic agents commonly used to treat this invalidating disorder or to identify target molecules for new therapeutic agents.

Estrogen-receptor polymorphisms and effects of estrogen replacement on high-density lipoprotein cholesterol in women with coronary disease

BACKGROUND

Sequence variants in the gene encoding estrogen receptor alpha (ER-alpha) may modify the effects of hormone-replacement therapy on levels of high-density lipoprotein (HDL) cholesterol and other outcomes related to estrogen treatment in postmenopausal women.

METHODS

We characterized 309 women with coronary artery disease who were enrolled in the Estrogen Replacement and Atherosclerosis trial with respect to eight previously described and two newly identified ER-alpha polymorphisms, and we examined the association between these polymorphisms and the response of HDL cholesterol and other lipids to treatment with estrogen alone or estrogen plus progestin.

RESULTS

After adjustment for age, race, diabetes status, body-mass index, smoking status, alcohol intake, and frequency of exercise, the 18.9 percent of the women who had the IVS1-401 C/C genotype (i.e., with C on both chromosomes in intervening sequence 1 at position 401 before exon 2) had an increase in the HDL cholesterol level with hormone-replacement therapy that was more than twice the increase observed in the other women (13.1 mg per deciliter vs. 6.0 mg per deciliter, P for treatment-by-genotype interaction = 0.004); this effect was limited to changes in the HDL subfraction 3 (HDL3) (P for interaction=0.04). Similar patterns of response were observed for three other highly linked ER-alpha intron 1 polymorphisms close to the IVS1-401 site (range of P values for interaction = 0.07 to 0.005). The pattern of increased response of HDL cholesterol in women with the IVS1-401 C/C genotype was evident in both the women receiving estrogen and those receiving estrogen plus progestin, was preserved across racial and ethnic groups, and was significant among women who were compliant with the study medication (P<0.001).

CONCLUSIONS

Postmenopausal women with coronary disease who have the ER-alpha IVS1-401 C/C genotype, or several other closely related genotypes, have an augmented response of HDL cholesterol to hormone-replacement therapy.

Estrogen receptor alpha polymorphism as a genetic marker for bone loss, vertebral fractures and susceptibility to estrogen

OBJECTIVE

The purpose of the present study was to investigate the possible roles of PvuII and XbaI polymorphisms of the estrogen receptor alpha (ER(alpha)) in bone mineral density (BMD), vertebral fracture, bone loss rate after menopause and response to hormone replacement therapy (HRT).

METHODS

All 286 women were grouped according to the genotypes of PvuII or XbaI polymorphisms of the ER(alpha) gene. We compared the BMD Z-score, incidence of vertebral fracture, changes in Z-score after menopause and response of BMD to HRT among the genotypes.

RESULTS

Subjects with the PPxx genotype had significantly (P<0.05) lower Z-scores than did subjects with the other genotypes. A negative correlation was observed between the length of time after menopause and the decrease of the Z-score only in women with the pp genotype, suggesting faster bone loss in this group. In the analysis of the ER(alpha) polymorphism with regard to the effect of HRT on BMD, there appears to be a significantly greater increase of BMD (P<0.01 and 0.05) in women with the pp genotype than in those with the Pp or PP genotype.

CONCLUSIONS

PvuII and XbaI polymorphisms of the ER(alpha) gene were associated with BMD in postmenopausal Japanese women. Also, the polymorphisms may be useful genetic markers for predicting vertebral fracture in relatively young postmenopausal women. The PvuII polymorphism may be associated with susceptibility to changes in estrogen level.

Two new single-nucleotide polymorphisms in the COL1A1 upstream regulatory region and their relationship to bone mineral density

Single-nucleotide polymorphisms (SNPs) in regulatory regions of candidate genes may determine variability in bone mineral density (BMD) because they may be responsible for differences in levels of a gene product in response to external signals. Under this hypothesis, we scanned an 800-base pair (bp) region within the COL1A1 promoter, known to harbor cis elements important for in vivo expression, and we found two new polymorphisms: -1663indelT and -1997 G/T. The G to T transversion at -1997 was associated with lumbar spine BMD (p = 0.015) when tested in a cohort of 256 postmenopausal women after adjusting by age, body weight, and years since menopause; a lower degree of association was detected also for femoral neck BMD in a subgroup of 146 women in univariate analysis and after adjusting by age (p = 0.044). The polymorphism -1663indelT, which corresponds to a deletion of a T in a tract of eight T residues (-1670 to -1663), did not show significant association with BMD. Interestingly, -1663indelT is in strong linkage disequilibrium (LD) with the previously described Sp1 polymorphism of intron 1, which in this study did not show association with BMD either. Significant interaction between -1997 G/T and -1663indelT (p = 0.019), and between -1997 G/T and Sp1 (p = 0.045) was observed also. Individuals heterozygous for the three polymorphisms showed the highest mean BMD value. Gel retardation assays showed that oligonucleotides containing either the -1663 or the -1997 polymorphic sites specifically bind primary osteoblast nuclear proteins. We named these binding sites as PCOL1 and PCOL2, respectively. In summary, this study describes two new SNPs in the COL1A1 promoter, which may affect bone mass determination.

Invited review: Pharmacogenetics of estrogen replacement therapy

There are a number of genetic factors that likely modulate both the beneficial and adverse effects of estrogen. An important domain of consideration is the relationship of estrogen and thrombosis risk. Gene polymorphisms among the key elements of the coagulation and fibrinolytic cascade appear to influence the effects of estrogen on risk for venous thromboembolic events and possibly arterial thrombosis as well. Emerging data also suggest that allelic variants in the estrogen receptor-alpha may modulate estrogen's effects, especially with respect to bone and lipid metabolism.

Association of a T262C transition in exon 1 of estrogen-receptor-alpha gene with skeletal responsiveness to estrogen in post-menopausal women

Polymorphic genetic markers of estrogen-receptor-alpha (ERalpha) gene studied so far in osteoporosis reside in non-coding region with uncertain functional significance. The purpose of the present study was to search for nucleotides changes in the exon 1 and 5' regulatory region of ERalpha gene, to study the nature of their linkages to the previously reported Pvull polymorphism in intron 1 and their functional significance in postmenopausal osteoporosis. Direct sequencing of exon 1 and promotor region of ERalpha gene revealed a synonymous nucleotide substitution from T to C at position 262, 29 nucleotides downstream from the putative start codon. No nucleotide change was found in the promotor region. Linkage disequilibrium between the T262C polymorphism and the Pvull polymorphism in intron 1 of ERalpha gene was demonstrated in 129 post-menopausal women (p<0.001). After treating 96 post-menopausal with 0.3 mg or 0.625 mg conjugated equine estrogen (CEE) for 2 yr, vertebral bone mineral density (BMD) increased regardless of the T262C genotype. However, with regard to femoral neck BMD, only those subjects that were homozygous for the T262C polymorphism had an increase in femoral BMD (+5.9+/-1.4%, mean+/-SE; p<0.0001). Using analysis of covariance to assess the effects of the T262C polymorphism, the intronic Pvull polymorphism, doses of CEE and the corresponding baseline BMD on the changes in vertebral or femoral BMD after treatments, it was found that the change in vertebral BMD was related only to the baseline BMD (p<0.05). The change in femoral BMD was independently related to the T262C polymorphism (p<0.01) and the baseline femoral BMD (p<0.01). No effect of the Pvull polymorphism or the doses of CEE on femoral BMD was demonstrated. We concluded that the previously described intronic Pvull polymorphism of ERalpha gene is in linkage disequilibrium with a T262C polymorphism in exon 1. This T262C polymorphism appears to be more directly related to the skeletal response after long-term treatment with estrogen.

Oestrogen receptor-alpha gene polymorphism is associated with endometriosis, adenomyosis and leiomyomata

Endometriosis, adenomyosis and leiomyomata develop in women of reproductive age and regress after menopause or ovariectomy, suggesting that they grow in an oestrogen-dependent fashion. We investigated whether polymorphism in the oestrogen receptor-alpha (ERalpha) gene is related to oestrogen-dependent benign uterine disease. A total of 203 women with regular menstrual cycles underwent laparotomy or laparoscopy and were diagnosed histologically with endometriosis, adenomyosis and/or leiomyomata. Patients with cervical carcinoma in situ, tubal occlusion or adhesion but no other gynaecological disease were considered to be disease-free. A total of 179 women undergoing annual health examination were grouped as reference population. The distribution of PVUII genotypes (PP, Pp, and pp) of the ERalpha gene was different between each pair of the four groups of endometriosis, adenomyosis/leiomyomata, disease-free, and reference population (P = 0.022-0.0005), except between the former two groups. The PP genotype was less frequent in the groups of endometriosis (P = 0.0002) and adenomyosis/leiomyomata (P = 0.002) as compared to that in the disease-free group. In the endometriosis group, there was no difference in the distribution of PVUII genotypes due to complicating diseases (adenomyosis and/or leiomyomata) or severity of the clinical stages. These results suggest that the PVUII polymorphism of the ERalpha gene is associated with the risk for endometriosis, adenomyosis, and leiomyomata.

The protective effect of hormone-replacement therapy on fracture risk is modulated by estrogen receptor alpha genotype in early postmenopausal women

Genetic factors regulate bone mineral density (BMD) and possibly development of osteoporosis. It has been suggested that estrogen receptor alpha (ERalpha) genotype is associated with BMD, but the association between ERalpha genotype, fracture risk, and postmenopausal hormone replacement therapy (HRT) has not been studied. Therefore, we evaluated whether ERalpha polymorphism is associated with fracture risk in a 5-year trial with HRT in a population-based, randomized group of 331 early postmenopausal women. The participants consisted of two treatment groups: the HRT group (n = 151) received a sequential combination of 2 mg of estradiol valerate (E2Val) and 1 mg of cyproterone acetate with or without vitamin D3, 100-300 IU + 93 mg calcium as lactate per day; and the non-HRT group (n = 180) received 93 mg of calcium alone or in combination with vitamin D3, 100-300 IU/day. All new symptomatic, radiographically defined fractures were recorded. Pvu II restriction fragment length polymorphism of the ERalpha was determined using polymerase chain reaction (PCR). In all, 28 women sustained 33 fractures during the approximately 5.1-year follow-up. In the HRT group, the ERalpha genotype (PP, Pp, and pp) was not significantly associated with fracture risk (p = 0.138; Cox proportional hazards model). When the genotype was dichotomized (PP + Pp vs. pp), the incidence of new fractures in the HRT group was significantly reduced in women with the P allele (p = 0.046) with the relative risk (HR) of 0.25 (95% CI, 0.07-0.98), in comparison with the non-P allele group. After adjustment for time since menopause and previous fracture, the association between the dichotomous genotype and fracture risk persisted with HR of 0.24 (95% CI, 0.06-0.95;p = 0.042). In the non-HRT group, the ERalpha genotype was not significantly associated with fracture risk. During HRT, women with the pp genotype have a greater fracture risk than those with the P allele. The results suggest that the pp genotype is a relatively hormone-insensitive genotype, and it appears that women with the P allele may benefit more from the protective effect of HRT on fracture risk than women with the pp genotype.