Luigi Gennari

Association of Polymorphisms of the Estrogen Receptor α 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 α 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 2229 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.

Circulating Sclerostin Levels and Bone Turnover in Type 1 and Type 2 Diabetes

CONTEXT Previous observations showed a condition of low bone turnover and decreased osteoblast activity in both type 1 and 2 diabetes mellitus (DM1 and DM2). Sclerostin is a secreted Wnt antagonist produced by osteocytes that regulates osteoblast activity and thus bone turnover. Its levels increase with age and are regulated by PTH. OBJECTIVES The aim of the present study was to evaluate circulating sclerostin levels in patients with DM1 or DM2 with normal renal function and to analyze its relationship with PTH, 25-hydroxyvitamin D, and bone turnover markers. DESIGN, AND SETTING: This was a cross-sectional study conducted at a clinical research center. PARTICIPANTS Forty DM2 and 43 DM1 patients were studied and compared with a reference control group (n = 83). RESULTS In the overall cohort, sclerostin levels were higher in males than in females and significantly increased with age in both genders. The positive correlation between sclerostin and age was maintained in DM1 but not in DM2 patients. Moreover, sclerostin levels were higher in DM2 than in controls or DM1 patients, and this difference persisted when adjustments were made for age and body mass index. Consistent with previous clinical and experimental observations, sclerostin was negatively associated with PTH in nondiabetic patients (r = -0.30; P < 0.01), independently of age and gender. Conversely, an opposite but nonsignificant trend between PTH and sclerostin was observed in both DM1 (r = 0.26; P = 0.09) and DM2 (r = 0.32; P = 0.07) cohorts. CONCLUSIONS These findings suggest that sclerostin is increased in DM2. Moreover, the transcriptional suppression of sclerostin production by PTH might be impaired in both DM1 and DM2.

Association of polymorphisms of the estrogen receptor alpha gene with bone mineral density and fracture risk in women

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 α 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 2229 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.

FokI Polymorphism at Translation Initiation Site of the Vitamin D Receptor Gene Predicts Bone Mineral Density and Vertebral Fractures in Postmenopausal Italian Women

A novel T/C polymorphism (ATG to ACG) at the translation initiation site of the vitamin D receptor (VDR) gene, defined by FokI restriction endonuclease, has been recently associated with variation in bone mineral density (BMD) and rates of bone loss in a group of postmenopausal Mexican‐American women. The presence of the restriction site, designated as f, allows protein translation to initiate from the first ATG, while the allele lacking the site, indicated as F, initiates translation at a second ATG. In this study, we investigated the role of FokI polymorphism in a group of 400 postmenopausal women of Italian descent stratified for BMD into osteoporotic (n = 164), osteopenic (n = 117), and normal (n = 119) groups. There were 159 (41%) FF homozygotes, 55 (14%) ff homozygotes, and 186 (45%) Ff heterozygotes. In the whole population, we observed a weak association between FokI polymorphism and lumbar BMD (p = 0.06, analysis of covariance [ANCOVA]) but not with femoral neck BMD (p = 0.5, ANCOVA). Interestingly, the effect of FokI genotypes on lumbar BMD was influenced by the years since menopause such that differences in BMD related to different VDR allelic variants were greater among women in the first 5 years of menopause (p = 0.04, ANCOVA), progressively declining afterward. In addition, a significantly higher prevalence of ff genotype in osteoporotic than in osteopenic and normal women was observed (p = 0.04, Chi‐square test). Finally, ff genotype resulted significantly over‐represented in the group of women with a vertebral fracture as compared with controls (p = 0.003, Chi‐square test), equivalent to a relative risk of 2.58 (95% confidence intervals 1.36–4.91). We conclude that in this population, FokI polymorphism at the VDR gene locus accounts for a part of the heritable component of BMD at the lumbar spine.

Vitamin D receptor genotypes and intestinal calcium absorption in postmenopausal women

Abstract. Several studies have shown that bone mass and bone turnover are genetically determined. This genetic component is thought to be mediated in part by polymorphisms at the vitamin D receptor (VDR) locus, even though the underlying molecular mechanisms are still unknown. To evaluate a possible site of differential action of the VDR gene alleles we examined their correlation with intestinal calcium absorption in 120 Caucasian postmenopausal women (aged 61 ± 0.6 years). VDR gene polymorphisms for Apa I, Bsm I, and Taq I restriction endonucleases were assessed by Southern blotting analysis. The most common genotypes observed in our population were AaBbTt (37%), AABBtt (20%), aabbTT (15%), AabbTT (15%), and AABbTt (9%). Although there was some evidence of 13% higher lumbar BMD values in aabbTT genotype with respect to AABBtt genotype, this difference of approximately 0.1 g/cm2 did not reach statistical significance, possibly because of the limited number of observations. On the contrary, no relationship was found between genotypes and femoral neck BMD values. Intestinal calcium absorption was significantly lower in BB and tt genotypes than, in bb and TT genotypes, respectively, and in AABBtt genotype than in either aabbTT or AaBbTt genotypes (P= 0.0015 ANOVA). No significant differences in intact PTH, alkaline phosphatase, 25OHD3, and 1,25(OH)2D3 were found among subjects with different VDR genotypes. These results are consistent with a possible role of VDR alleles on intestinal calcium absorption.

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.

Selective estrogen receptor modulators for postmenopausal osteoporosis : Current state of development

Selective estrogen receptor modulators (SERMs) are structurally different compounds that interact with intracellular estrogen receptors in target organs as estrogen receptor agonists and antagonists. These drugs have been intensively studied over the past decade and have proven to be a highly versatile group for the treatment of different conditions associated with aging, including hormone-responsive cancer and osteoporosis. Tamoxifen and toremifene are currently used to treat advanced breast cancer and also have beneficial effects on bone mineral density and serum lipids in postmenopausal women. Raloxifene is the only SERM approved worldwide for the prevention and treatment of postmenopausal osteoporosis and vertebral fractures. However, although these SERMs have many benefits, they may also be responsible for some potentially very serious adverse effects, such as thromboembolic disorders and, in the case of tamoxifen, uterine cancer. These adverse effects represent a major concern given that long-term therapy is required to prevent osteoporosis. Moreover, both preclinical and clinical reports suggest that tamoxifen, toremifene and raloxifene are considerably less potent than estrogen.The search for the ‘ideal’ SERM, which would have estrogenic effects on bone and serum lipids, neutral effects on the uterus, and antiestrogenic effects on breast tissue, but none of the adverse effects associated with current therapies, is currently under way. Ospemifene, lasofoxifene, bazedoxifene and arzoxifene, which are new SERM molecules with potential greater efficacy and potency than previous SERMs, are currently under investigation for use in the treatment and prevention of osteoporosis. These drugs have been shown to be comparably effective to conventional hormone replacement therapy in animal models of osteoporosis, with potential indications for an improved safety profile. Clinical efficacy data from ongoing phase III trials are awaited so that a true understanding of the therapeutic potential of these compounds can be obtained.

Prevalence of Paget's disease of bone in Italy

We examined the prevalence of PDB in Italy from radiological, scintigraphic, and biochemical surveys in two Italian towns. Prevalence rates varied from 0.7% to 2.4%, were higher in males than in females, and slightly differed between the two towns. Unlike previous studies in populations of British descent, no secular trend for a decreasing prevalence emerged.

Alendronate Treatment in Men With Primary Osteoporosis: A Three-Year Longitudinal Study

Bisphosphonates have been widely used in the treatment of osteoporosis in women, whereas until now there have been few data on their use in men. The aim of this study was to evaluate the effect of a 3-year alendronate treatment on bone mineral density (BMD) and quantitative ultrasound (QUS) in men with primary osteoporosis. We studied 77 osteoporotic men (aged 57.1 ± 10.8 yrs) who completed a 3-year treatment with alendronate (10 mg/day) plus calcium (1000 mg/day) (n = 39), or calcium alone (n = 38). At baseline and at a 12-month interval, we measured BMD at the lumbar spine and femur (femoral neck and total hip) by DXA (Hologic) and speed of sound (SOS), broadband ultrasound attenuation (BUA) and Stiffness (S) at the os calcis by Achilles plus (Lunar). Alendronate treatment had significantly increased lumbar spine BMD by 4.2% at year 1, by 6.3% at year 2, and 8.8% at year 3. BMD at the femoral neck and total hip had increased by 2.1% and 1.6% at year 1, by 3.2% and 2.9% at year 2, and by 4.2% and 3.9% at year 3, respectively. BUA and Stiffness showed a significant increase in the alendronate-treated group at year 2 (3.2% and 4.9%, respectively) and at year 3 (3.8% and 6%, respectively). BMD at the lumbar spine showed the best longitudinal sensitivity whereas longitudinal sensitivity of both QUS at the heel and femur BMD were similar. In conclusion, this study confirms that alendronate represents an important therapeutic advance in the management of male osteoporosis. BMD at the lumbar spine appears to be the best method for monitoring the effect of alendronate on bone mass in osteoporotic men.

Quantitative ultrasound and dual-energy X-ray absorptiometry in the prediction of fragility fracture in men

Fragility fractures in men represent a major health problem, and this prompts a necessity for reliable tools for the identification of men at risk of fracture. In order to assess the ability of dual-energy X-ray absorptiometry (DXA) and quantitative ultrasound (QUS) in the prediction of fracture risk in men and whether their combination might be useful in a clinical setting, we studied 401 men (age range 45–82 years, mean 60.3±12.5), of whom 133 had osteoporotic fractures and 268 did not. In all subjects we measured bone mineral density at the lumbar spine (BMD-LS) and at the femur, calculating thereafter the standard femoral subregions: neck (BMD-FN), total hip (BMD-T), trochanter (BMD-TR), intertrochanter (BMD-ITR), and Ward’s triangle (BMD-W), by DXA. We also performed ultrasound parameters at the calcaneus: speed of sound (SOS), broadband ultrasound attenuation (BUA) and Stiffness, by Achilles plus, and at the phalanxes: amplitude dependent speed of sound (AD-SoS) and the parameters of the graphic trace: bone transmission time (BTT), fast wave amplitude (FWA), signal dynamic (SDy) and ultrasound bone profile index (UBPI), by Bone Profiler. All DXA and QUS parameters, apart from FWA, were significantly (P<0.001) lower in patients with a history of fracture. BMD at the proximal femur showed the best ability in discriminating men with or without fractures. QUS at the heel showed discriminatory ability significantly better than QUS at the fingers. By logistic regression analysis, adjusted for age and BMI, BMD-T showed the best association with fragility fracture [odds ratio (OR)=3.43, 95% confidence interval (CI)=2.47–4.77]. Among QUS parameters, the highest value of the OR was shown by stiffness (OR=3.18, CI=2.27–4.48). FWA and SDy were not associated with fragility fractures in men. If DXA and QUS were combined, the prediction of the OR of fragility fracture events in men increases; in fact Stiffness was able to increase the OR when added to BMD-LS (OR=5.44, CI=3.16–10.13) and BMD-T (OR=6.08, CI=2.63–14.27). SOS and BUA showed a similar pattern. AD-SoS improved the prediction of fracture only when combined with BMD-LS (OR=4.36, CI=1.99–9.57). If BMD-LS and BMD-FN or BMD-T were combined, the value of the OR increases (OR=4.59, CI=2.27–9.25 and OR=4.68, CI=2.24–9.76), respectively. Our study supports the effectiveness of QUS in the identification of osteoporotic fractures in men. QUS seems to play an independent and complementary role, with respect to DXA, in order to enhance the power for predicting osteoporotic fractures in men.