Mutational and polymorphic analysis of the estradiol receptor-alpha gene in men with symptomatic vertebral fractures

Relationship of oestrogen receptor alpha gene polymorphisms with risk for benign prostatic hyperplasia and prostate cancer in Chinese men

The relationship of oestrogen receptor with benign prostatic hyperplasia (BPH) and prostate cancer (PC) is not clear at present. This study aimed to investigate the molecular mechanism underlying the occurrence and development of BPH and prostate.Two hundred forty-four PC cases, 260 BPH patients, and 222 healthy men were recruited from Han people in China, and the oestrogen receptor alpha (ESRα) gene polymorphism (rs2234693 [PvuII] and rs9340799 [XbaI]) on intron 1 was determined. The relationship of gene polymorphism with PC and BPH was evaluated with Logistic regression, and the linkage disequilibrium and haplotyping were assessed with SHEsis software.The risk for PC in BPH patients with PvuII C allele was higher (OR = 1.437, 95% CI: 1.110-1.859), but the differentiation degree of cancer cells was relatively better in PC patients with PvuII C allele (OR = 0.419, 95% CI: 0.285-0.616), and most of them are circumscribed (OR = 0.706, 95% CI: 0.485-1.02). There was significant linkage disequilibrium between PvuII and XbaI. The genotype TTAG not only induced BPH (OR = 6.260, 95% CI: 1.407-27.852), but increased the risk for PC (OR = 6.696, 95% CI: 1.504-29.801). However, the genotype TTAG in BPH patients had no relationship with the risk for PC (P > 0.05). Furthermore, men with haplotype TG were more likely to suffer PC (OR = 9.168, 95% CI: 2.393-35.119), but men with haplotype TA and enlarged prostate had a low risk for PC (OR = 0.708, 95% CI: 0.551-0.912).These results show the relationship between ESRα gene polymorphism and susceptibility to PC and BPH in Chinese men, and the ethnic and regional difference as well.

Polymorphisms in the estrogen receptor genes are associated with hip fractures in Chinese

INTRODUCTION

Hip fractures (HF) are a major cause of public health burden with strong genetic determination. However, the true causal genes remain largely unknown.

MATERIALS AND METHODS

Based on the important biological role of estrogens in bone homeostasis, this study aimed to investigate whether the estrogen receptor genes, ESR1 and ESR2, affect the onset of HF in 700 elderly Chinese subjects (350 with osteoporotic HF and 350 healthy controls). We genotyped 32 SNPs in total and examined their associations both by the single-SNP and haplotype tests.

RESULTS

We identified two novel SNPs of ESR1, rs3020314 and rs1884051, were significantly associated with HF (rs3020314: P=0.0004, OR=1.66, 95%CI: 1.25-2.18; rs1884051: P=0.0004, OR=1.46, 95%CI: 1.19-1.81). We firstly detected significant association of ESR2 with HF (rs960070: P=0.0070, OR=1.43, 95%CI: 1.10-1.86). Haplotype analyses corroborated our single-SNP results.

CONCLUSION

Our findings have important implications for understanding the pathology of osteoporotic fractures. Independent replication studies are needed to validate our results and explore the most possible functional variants for molecular studies.

Vitamin D-binding protein gene microsatellite polymorphism influences BMD and risk of fractures in men

Here we report the results of a vitamin D-binding protein gene microsatellite polymorphism study in 170 men, comprising healthy male subjects and men with osteoporosis-related symptomatic vertebral fractures. We confirm the results of an earlier study in a different cohort, showing relationship between certain genotypes of (TAAAn)-Alu repeats and reduced BMD and vertebral fractures.

INTRODUCTION

Vitamin D-binding protein (DBP) plays a critical role in the transport and metabolism of metabolites of vitamin D, including the key calciotropic hormone 1alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3).

METHODS

We have investigated intra-intronic variable tandem (TAAA)n-Alu repeat expansion in the DBP gene in 170 men, comprising healthy male subjects and men with idiopathic osteoporosis and low trauma fractures.

RESULTS AND CONCLUSIONS

The predominant DBP-Alu genotype in the control subjects was 10/10 (frequency 0.421), whereas the frequency of this genotype in men with osteoporosis was 0.089. DBP-Alu alleles *10, *8 and *9, respectively, were the three commonest in both healthy subjects and men with osteoporosis. Allele *10 was associated with a lower risk of osteoporosis (OR 0.39, 95% CI 0.25-0.64; p < 0.0005), as was allele *11 (odds ratio 0.09, 95% CI 0.01-0.67; p < 0.007). Logistic regression gave similar results, showing that individuals with genotype 10/10 and 19-20 repeats (genotypes 9/10, 9/11, 10/10,) are protected from fracture or osteoporosis. Overall, there was a relationship between DBP Alu genotype and BMD, suggesting that DBP-Alu genotype may influence fracture risk. This effect may be mediated by changes in the circulating concentrations of DBP which influences free concentrations of vitamin D.

Interactions between effects of estrogen receptor gene polymorphisms on BMD and experiences of the first spermorrhea in Chinese Han boys

OBJECTIVE

To study the interaction between polymorphisms of estrogen receptor (ER) gene and puberty on bone mineral density (BMD).

METHODS

One hundred and forty-six boys aged 13-17 years were divided into two groups according to their first spermorrhea. DNA was analyzed for Xba I and Pvu II genotypes by PCR-RFLP. BMD of the total body, forearm and lumbar spine was measured by dual-energy X-ray absorptiometry (DXA). The relationship between polymorphisms of ER gene and BMD in these two groups was analyzed.

RESULTS

The BMD at all sites in the spermorrhea group was significantly higher than that in the un-spermorrhea group. The independent contribution of ER genotypes to BMD at two pubertal stages was analyzed after adjusting co-variables. In the un-spermorrhea group, the BMD at distal 1/10 and 1/3 forearm of those carrying pp genotype was significantly higher than that of the non-carries, whereas in the spermorrhea group BMD in those carrying the same genotype was significantly lower than that in the non-carriers. Similar results were obtained by haplotype analysis. Multiple stepwise regression analysis showed that body weight, age and the first spermorrehea were the dominant determinants for BMD. BMD at forearm might be influenced by interaction between ER genotype and the first spermorrehea.

CONCLUSION

The polymorphisms of ER gene play a different role in BMD influenced by the first spermorrhea. Chinese boys carrying p or x allele should pay more attention to their bone mass.

Searching for genes underlying susceptibility to osteoporotic fracture: current progress and future prospect

INTRODUCTION

Osteoporotic fracture (OF) is a public health problem. It is a common practice in the genetics of osteoporosis that bone mineral density (BMD) was studied as a major surrogate phenotype in gene search for risk of OF (ROF) because of their high phenotypic correlation. However, some studies indicate that the genetic correlation between BMD and ROF is very low. This implies that most genes found important for BMD may not be relevant to ROF. Ideally, employing OF per se as a direct study phenotype can directly find the relevant genes underlying ROF.

EVIDENCE

Here, we summarized some evidence supporting ROF under moderate genetic control, and the current progress of molecular genetic studies employing OF as the direct study phenotype, then give our consideration on the future prospects in the genetics of ROF.

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.

Molecular genetic studies of gene identification for osteoporosis: a 2004 update

This review summarizes comprehensively the most important and representative molecular genetics studies of gene identification for osteoporosis published up to the end of December 2004. It is intended to constitute a sequential update of our previously published review covering the available data up to the end of 2002. Evidence from candidate gene association studies and genome-wide linkage studies in humans, as well as quantitative trait locus mapping animal models are reviewed separately. Studies of transgenic and knockout mice models relevant to osteoporosis are summarized. An important extension of this update is incorporation of functional genomic studies (including DNA microarrays and proteomics) on osteogenesis and osteoporosis, in light of the rapid advances and the promising prospects of the field. Comments are made on the most notable findings and representative studies for their potential influence and implications on our present understanding of genetics of osteoporosis. The format adopted by this review should be ideal for accommodating future new advances and studies.

Polymorphisms in androgen and estrogen receptor genes: effects on male aging

Besides lifestyle and environmental factors, the life-long exposure to the endocrine milieu of gonadal steroids is a determining factor to gender specific features of aging. In contrast to women, men do not experience a sudden cessation of gonadal function comparable to menopause. However, cross-sectional and longitudinal population studies demonstrate that the hormones with anabolic actions (e.g. testosterone [T], growth hormone, insulin-like growth factor [IGF]-1, dehydroepiandrosterone) do decrease progressively with aging in healthy men, and chronic systemic illnesses accelerate this process. In addition, estrogen has recently been established to be essential for normal physiology of the male. The slow progressive decline of the hypothalamic-pituitary-gonadal (HPG) function is thought to be responsible for many common signs and symptoms of aging men, such as general weakness, sexual dysfunction, and increased fat mass. There is a large inter-individual variation in sex hormone levels cross-sectionally within given age groups as well as longitudinally with aging. A contributing factor to this variability are the numerous functionally significant polymorphisms that have been detected in the receptors for androgen and estrogen. In this review, we summarize the recent information on some common polymorphisms in androgen and estrogen receptor genes and their effect on gender specific and aging-related symptoms and diseases of men.

Idiopathic or Hypogonadal Osteoporosis in Men

Osteoporosis is being recognized increasingly in men, and represents a substantial public health problem. As the male population ages and lives longer, the incidence of osteoporotic fractures is expected to increase. The current lifetime risk for a fragility fracture is approximately 27% in men aged 50 years or more, and will increase further over the next 20 years. A major problem with osteoporosis in men is that it continues to be unrecognized, and the majority of men with fragility fractures due to osteoporosis are not being treated. A higher level of awareness is required amongst both general practitioners and the general public that osteoporosis is a treatable condition that can affect men. Secondary causes for osteoporosis are more common in men than in women, and require rigorous exclusion and treatment. Undiagnosed clinical hypogonadism is a common cause of osteoporosis in men, and is readily treatable. The cause of primary osteoporosis in men is unknown, but it results in an osteoblast defect. Genetic factors are likely to be important. In some but not all men, relative estrogen deficiency contributes to rapid rates of age-related bone loss and fractures. An adequate calcium intake, regular weight-bearing exercise, and normal vitamin D status are all very important, particularly with increasing age. The role of testosterone in treating eugonadal men with osteoporosis is currently unclear, and larger prospective studies will be required to carefully evaluate the benefits and risks of therapy. First-line treatment of osteoporosis in hypogonadal or eugonadal men is with bisphosphonates. Alendronate increases bone density and reduces vertebral fractures measured using a semiquantitative method in eugonadal or hypogonadal men with osteoporosis. In the near future, it is likely that subcutaneous human parathyroid hormone (1-34) or teriparatide will also be available as an important new anabolic treatment for men with osteoporosis. Teriparatide treatment also increases bone density in men. Selective estrogen receptor modulating drugs require further evaluation in men, but would appear to theoretically benefit men, especially those with low estradiol levels. In the future, selective androgen receptor modulating drugs may be useful in the prevention and treatment of osteoporosis, and in increasing lean body mass in men, without having adverse effects on prostate and breast tissue.