Determinants of peak bone mass: clinical and genetic analyses in a young female Canadian cohort

Adolescents with idiopathic scoliosis are not osteoporotic

STUDY DESIGN

Case controlled study.

OBJECTIVE

To explore the relative effects of body mass index (BMI) and the presence or absence of adolescent idiopathic scoliosis (AIS) on bone mineral density (BMD) as evidenced by Z-scores in adolescents.

SUMMARY OF BACKGROUND DATA

Prior studies have identified adolescents with idiopathic scoliosis as having "osteoporosis" or "osteopenia," when only a small percentage of subjects in these studies actually had bone density that was clinically abnormal. The terms osteoporosis and osteopenia as used in adults cannot be applied to adolescents and children, as fracture risk has not been well correlated to Z-scores. As we had noted that our scoliosis patients of normal and heavy weight had normal Z-scores, this study was undertaken to explore the relationship of bone mineral density to body mass index in adolescents with and without scoliosis.

METHODS

Dual energy x-ray absorptiometry (DXA) scans of 49 adolescents with adolescent idiopathic scoliosis were compared to 40 normal control adolescents. Z-scores were compared to reduce variability when comparing subjects of varying age and genders. Student t test or simple linear regression was used to explore relationships between Z-scores and clinical and demographic variables.

RESULTS

In both groups of subjects, Z-score was most strongly correlated with BMI (P < 0.001). The presence of scoliosis had the effect of lowering the Z-score as if the individual had "lost" 3.4 BMI units.

CONCLUSION

Z-scores in subjects with and without scoliosis were most strongly correlated to BMI: thin patients had lower bone density, heavy patients had higher. The presence of scoliosis had an effect similar to subtracting 3.4 "BMI units," lowering the Z-score from what might otherwise be predicted. The "scoliosis effect" may be noticeable in thin individuals, pushing them to the "low for age" level, whereas in heavier individuals, the effect is negligible. No subjects in either group met the ISCD definition for osteoporosis.

Association between caffeine intake and bone mass among young women: potential effect modification by depot medroxyprogesterone acetate use

This study assessed associations between habitual caffeine intake and bone mass among young women. Analyses of the entire study population revealed no significant associations, while analyses restricted to women using depot medroxyprogesterone acetate (DMPA) showed modest inverse associations between caffeine intake and bone mineral content (BMC).

INTRODUCTION

Some previous investigations among postmenopausal women suggest an inverse relationship between caffeine intake and bone mass, yet studies of this association among young women are few.

METHODS

The association between habitual caffeine intake and bone mass was evaluated prospectively in a population-based cohort of 625 females, aged 14 to 40 years, adjusting for relevant biological and lifestyle factors. Caffeinated beverage intake was self-reported, and bone mineral content (BMC) and bone mineral density (BMD) were measured at baseline and every 6 months throughout a 24-month follow-up period using dual-energy x-ray absorptiometry.

RESULTS

Cross-sectional analyses revealed no significant differences in mean BMC or BMD at baseline. Mean percentage and absolute changes in BMC and BMD were not associated with caffeine use. Repeated measures analyses similarly showed no significant association between caffeine intake at baseline and mean BMC or BMD measured during follow-up. However, among women using depot medroxyprogesterone acetate (DMPA), modest inverse associations between caffeine and BMC (but not BMD) were detected.

CONCLUSIONS

Our data suggest that heavy habitual consumption of caffeinated beverages does not adversely impact bone mass among young women in general. Greater caffeine intake may be associated with lower BMC among DMPA users.

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

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

A prospective investigation of the relations among cognitive dietary restraint, subclinical ovulatory disturbances, physical activity, and bone mass in healthy young women

BACKGROUND

Cognitive dietary restraint (CDR) may mediate subclinical ovulatory disturbances, which may result in loss of bone mineral density (BMD). CDR is associated with greater physical activity, which may modify the effect of CDR and ovulatory disturbances on bone mass.

OBJECTIVE

We aimed to investigate the relations among CDR, ovulatory disturbances, and physical activity and their effect on BMD in healthy premenopausal women over a 2-y period.

DESIGN

In this prospective cohort study, key explanatory factors, important covariates, and BMD were measured at baseline and at 12 and 24 mo; 225 women completed the baseline assessment, and 189 completed the study. CDR was measured with the Three-Factor Eating Questionnaire, and physical activity was measured with the Baecke scale. An average of 9.8 menstrual cycles in 2 y were monitored by using salivary progesterone measurements and urinary ovulation detection kits. Ovulatory disturbances included anovulatory cycles or short luteal phase lengths of <10 d. BMD at the lumbar spine, femoral neck, and total body was measured by using dual-energy X-ray absorptiometry. General linear mixed modeling was used to determine predictors of change in BMD over time.

RESULTS

CDR was not associated with ovulatory disturbances or changes in BMD. The average annual rate of change in lumbar spine BMD was decreased by 0.01 g/cm(2) in women who had experienced > or =3 monitored cycles with ovulatory disturbances (P = 0.02).

CONCLUSIONS

CDR did not predict bone loss, and there was no relation between CDR and ovulatory disturbances. Ovulatory disturbances had a negative effect on the rate of change at the lumbar spine. The cause of these disturbances is unknown.

Higher prevalence of osteoporosis among female Holocaust survivors

The prevalence of osteoporosis was statistically significantly higher among female Holocaust survivors than among those who were not exposed to the Holocaust. These findings support the importance of nutrition and environmental conditions during childhood and adolescence on BMD in older adults.

INTRODUCTION

Holocaust survivors during childhood and adolescence experienced undernutrition and lack of exercise and sunlight. The study aimed to establish if Holocaust survivors have higher prevalence of osteoporosis than subjects who were not Holocaust survivors.

METHODS

Seventy-three female Jewish Holocaust survivors > or = 60 years old and 60 female European-born Jews > or =60 years old who were not in the Holocaust were examined. BMD was measured using DXA of the lumbar spine and hips. The Cochran-Armitage trend test was used to test for an increasing trend in decreased BMD in the Holocaust survivors versus controls.

RESULTS

Among Holocaust survivors 54.8% had osteoporosis, 39.7% osteopenia, and 5.5% normal BMD, whereas among controls 25.0% had osteoporosis, 55.0% osteopenia, and 20.0% normal BMD (p = 0.0001). In those who were <17 years old in 1945, among Holocaust survivors 58.0% had osteoporosis, 34.0% osteopenia, and 8.0% normal BMD, whereas among controls 20.0% had osteoporosis, 57.8% osteopenia, and 22.2% normal BMD (p = 0.0003). In those > or =17 years old in 1945, among Holocaust survivors 47.8% had osteoporosis, 52.2% osteopenia and none had normal BMD, whereas among controls 40.0% had osteoporosis, 46.7% osteopenia, and 13.3% normal BMD (p = 0.28).

CONCLUSION

The prevalence of osteoporosis was significantly higher among Holocaust survivors.

The influence of lifestyle, menstrual function and oral contraceptive use on bone mass and size in female military cadets

Purpose

To determine the influence of menstrual irregularity, oral contraceptive use and other factors on bone mineral density (BMD) and bone size at different skeletal sites in 135 college-aged fit women.

Methods

Menstrual history, oral contraceptive use, exercise history, and nutritional factors including calcium, caffeine, and alcohol intake as well as tobacco use were determined by written survey. Height, weight and fitness levels were measured. Spine and hip BMD were measured by dual x-ray absorptiometry (DXA), calcaneus BMD by peripheral DXA, and tibial bone mineral content (BMC) and size by peripheral Quantitative Computed Tomography (pQCT).

Results

The mean age was 18.4 ± 0.8 years. Weight and prior exercise were positively related to BMD at most skeletal sites and to tibial bone size. Milk intake was positively related to calcaneal BMD, tibial BMC and cortical thickness. Fracture history was an important predictor of spine, hip and heel BMD. Women who had ≥ 10 menstrual cycles in the year prior to BMD measurement had higher BMD at all sites as well as a greater tibial mineral content and cortical thickness than women who had oligomenorrhea/amenorrhea (≤ 9 cycles in the prior year; all p < 0.05). Oral Contraceptive (OC) users had significantly lower BMD in the spine (p < 0.02) and calcaneus (p = 0.04), smaller tibial periosteal circumference and lower tibial mineral content (p < 0.02) than non-OC users.

Conclusion

In a population of fit, college-aged women, OC use and oligomenorrhea were associated with reduced BMD and bone size. Weight, as well as prior exercise and milk intake was positively related to bone density and size at some skeletal sites. Understanding these relationships would help improve skeletal health in young women.

The effect of LRP5 polymorphisms on bone mineral density is apparent in childhood

Bone mass acquired during childhood is the primary determinant of adult bone mineral density (BMD) and osteoporosis risk. Bone accrual is subject to genetic influences. Activating and inactivating LRP5 gene mutations elicit extreme bone phenotypes, while more common LRP5 polymorphisms are associated with normal variation of BMD. Our aim was to test the hypothesis that LRP5 gene polymorphisms influence bone mass acquisition during childhood. The association between LRP5 gene polymorphisms and bone size and mineralization was examined in 819 unrelated British Caucasian children (n = 429 boys) aged 9 years. Height, weight, pubertal status (where available), total-body and spinal bone area, bone mineral content (BMC), BMD, and area-adjusted BMC (aBMC) were assessed. Dual-energy X-ray absorptiometry (DXA)-gene associations were assessed by linear regression, with adjustment for age, gender, pubertal status, and body size parameters. There were 140, 79, 12, and 2 girls who achieved Tanner stages I-IV, respectively, and 179 and 32 boys who achieved Tanner stages I and II, respectively. The rs2,306,862 (N740N) coding polymorphism in exon 10 of the LRP5 gene was associated with spinal BMD and aBMC (each P = 0.01) and total-body BMD and aBMC (P = 0.04 and 0.03, respectively). Adjusting for pubertal stage strengthened associations between this polymorphism and spinal BMD and aBMC (P = 0.01 and 0.002, respectively). Individuals homozygous for the T allele had greater spinal BMD and aBMC scores than those homozygous for the C allele. A dose effect was apparent as the mean spinal BMD and aBMC of heterozygous TC individuals were intermediate between those of their TT and CC counterparts. The N740N polymorphism in exon 10 of LRP5 was associated with spinal BMD and aBMC in pre- and early pubertal children. These results indicate that LRP5 influences volumetric bone density in childhood, possibly through effects on trabecular bone formation.

LRP5 coding polymorphisms influence the variation of peak bone mass in a normal population of French-Canadian women

INTRODUCTION

Bone mineral density has a strong genetic component but it is also influenced by environmental factors making it a complex trait to study. LRP5 gene was previously shown to be involved in rare diseases affecting bone mass. Mutations associated with gain-of-function were described as well as loss-of-function mutations. Following this discovery, many frequent LRP5 polymorphisms were tested against the variation of BMD in the normal population.

MATERIALS AND METHODS

Heel bone parameters (SOS, BUA) were measured by right calcaneal QUS in 5021 healthy French-Canadian women and for 2104 women, BMD evaluated by DXA at two sites was available (femoral neck (FN) and lumbar spine (LS)). Among women with QUS measures and those with DXA measures, 26.5% and 32.8% respectively were premenopausal, 9.2% and 10.7% were perimenopausal and 64.2% and 56.5% were postmenopausal. About a third of the peri- and postmenopausal women never received hormone therapy. Two single nucleotide coding polymorphisms (Val667Met and Ala1330Val) in LRP5 gene were genotyped by allele-specific PCR. All bone measures were tested individually for associations with each polymorphism by analysis of covariance with adjustment for non genetic risk factors. Furthermore, haplotype analysis was performed to take into account the strong linkage disequilibrium between the two polymorphisms.

RESULTS AND CONCLUSION

The two LRP5 polymorphisms were found to be associated with all five bone measures (L2L4 and femoral neck DXA as well as heel SOS, BUA and stiffness index) in the whole sample. Premenopausal women drove the association as expected from the proposed role of LRP5 in peak bone mass. Our results suggest that the Val667Met polymorphism is the causative variant but this remains to be functionally proven.

Determinants of bone mineral density in Chinese-American women

SUMMARY

Few data are available regarding bone mineral density (BMD) and its determinants among Chinese Americans. We identified determinants of BMD among 359 Chinese-American women in order to identify risk factors for low BMD in this burgeoning population. BMD in Chinese-American women is influenced by a number of factors, including immigration.

INTRODUCTION

Osteoporosis and low BMD are common among Chinese women, including Chinese Americans, who are a growing population at risk for osteoporosis in the US. Few data are available regarding BMD and its determinants among Chinese-American women.

METHODS

In this study, we examined predictors of BMD in 359 ambulatory Chinese-American women, ages 20-90, using stepwise multiple regression analysis. Variables in the model included age, weight, height, menarche age, years since menopause, immigration age, years in US, percentage of life in US, number of pregnancies, oral contraceptive use, family history of osteoporosis, family history of hip fracture, daily calcium intake, exercise, time outdoors, alcohol consumption and tobacco use.

RESULTS

Among premenopausal women, weight was the strongest predictor of BMD, accounting for 10.5% of the variance at the lumbar spine (LS), 15.2% at the total hip (TH) and 16.6% at the femoral neck (FN). Time outdoors was also a positive predictor of BMD (1.4% at LS, 2.8% at TH and 1.6% at FN), while family history of osteoporosis (1.4% at TH) and age (3.7% at FN) were negative predictors. Among postmenopausal women, greater BMD at the LS and TH was associated with greater weight and earlier immigration age. Weight accounted for 16.4% of the variance at the LS and 19.8% at the TH; immigration age accounted for 3.1% of the variance at the LS and 4.1% at the TH. At the FN, years since menopause and weight were predictors of BMD, accounting for 14.4% and 8.7% of the variance, respectively. While older age at immigration had a negative effect on BMD, years in and proportion of life in the United States were not significant predictors of BMD.

CONCLUSIONS

Bone mineral density in Chinese-American women is influenced by a number of biological and lifestyle factors, including immigration. The results of this study provide new insights into risk factors for low bone density as they relate to environmental determinants in the growing population of Chinese-American women.

Vitamin D status and its relationship with parathyroid hormone and bone mineral status in older adolescents

Osteoporosis is an important contributor to the global burden of disease, and in the UK alone results in one in three women and one in twelve men aged >50 years experiencing a fragility fracture. Optimising peak bone mass in early adulthood is thought to reduce osteoporosis risk by offsetting bone losses in later life. Ensuring sufficient vitamin D status (measured as 25-hydroxyvitamin D (25OHD) in plasma), among other factors, is believed to facilitate the achievement of optimum peak bone mass. Lower 25OHD is associated with a higher plasma concentration of parathyroid hormone (PTH). As PTH is associated with increased bone turnover and bone loss, maintenance of sufficient 25OHD is thought to have a protective effect on bone health. However, there is a lack of consensus internationally on what constitutes an optimum 25OHD concentration, and values between 30 and 80 nmol/l have been suggested. These values have been based on findings from various studies in adults in which PTH has been observed to plateau at a 25OHD concentration of >30 nmol/l; however, not all studies have found such a plateau. Although studies in younger adolescents (14–16 years) have shown an inverse relationship between PTH and 25OHD, the concentration of 25OHD required for achievement of optimum peak bone mass is unknown. The present review examines the evidence defining vitamin D insufficiency thresholds, and the relevance of such thresholds to adolescent bone health.

Intraskeletal variability in bone mass

For methodological or other reasons, a variety of skeletal elements are analyzed and subsequently used as a basis for describing general bone loss and mass. However, bone loss and mass may not be uniform within and among skeletal elements of the same individual because of biomechanical factors. We test the hypothesis that a homogeneity in bone mass exists among skeletal elements of the same individual. Measures indicative of bone mass were calculated from the midshafts of six skeletal elements from the same individuals (N = 41). The extent of intraskeletal variability in bone mass (relative cortical area) was then examined for the entire sample, according to age, sex, and pathological status. The results of the analysis showed that all measures reflect a heterogeneity in bone mass (P </= 0.001). Specifically, differences were observed between the bones of the upper limb and those of the lower limb. Both sexes showed intraskeletal variability in bone mass, but the difference between the sexes is not significant (P = 0.509). When the sample is subdivided according to age, all groups show intraskeletal variability in bone mass, but the difference did not differ significantly among the groups (P = 0.217). However, significant differences in intraskeletal variability are observed between individuals below and above the age of 50. Pathological individuals show intraskeletal variability in bone mass, but the difference between the pathological and non-pathological groups is not significant (P = 0.095). These results indicate that the bone mass of any particular skeletal element is intricately tethered to its specific mechanical loading environment.

Relationship of the human growth hormone receptor exon 3 genotype with final adult height and bone mineral density

CONTEXT

Three recent clinical studies have reported that two of the most common isoforms of the human GH (hGH) receptor (hGHR), exon 3 full-length (3+) and exon 3 deleted (3-), may have differential effects on the growth response of children receiving hGH therapy, whereas others refute this. However, none of the investigations has explored the relationship between these hGHR isoforms and final adult height (FAH) or measures of bone mineral density (BMD) within a healthy adult population.

OBJECTIVE

The aim of this study was to investigate the possible influences of hGHR exon 3 isoforms on FAH and BMD measures of a normal population.

DESIGN

The study was designed to correlate the hGHR exon 3 genotype of a cohort of healthy adults with FAH, BMDs [spine (L2-L4) and hip (femoral neck)], and quantitative ultrasound (QUS) of the heel.

PATIENTS

Participants were 368 unrelated healthy adult white women, aged 18-35 yr.

MAIN OUTCOME MEASURES

We analyzed association of hGHR exon 3 genotypes with FAH, BMD, and QUS. Heights were measured using a stadiometer, BMDs using dual-energy x-ray absorptiometry, and QUS by standard technique. Detailed medical histories, including lifestyle factors, were obtained using a standardized interview.

RESULTS

The distribution of hGHR genotypes in the 368 samples was 53.3% for 3+/3+, 35.6% for 3+/3-, and 11.1% for 3-/3-. There was no correlation between the hGHR exon 3 genotypes and FAH, BMD, or QUS in this cohort.

CONCLUSION

The hGHR 3+ and 3- isoforms appear not to have differential effects on two major growth outcomes of hGH action, FAH, and BMD in a population of healthy adult women.

Association between SNP and haplotypes in PPARGC1 and adiponectin genes and bone mineral density in Chinese nuclear families

AIM

To assess the contribution of single nucleotide polymorphisms (SNP) and haplotypes in the peroxisome proliferators-activated receptor-gamma co-activator-1 (PPARGC1) and adiponectin genes to normal bone mineral density (BMD) variation in healthy Chinese women and men.

METHODS

We performed population-based (ANOVA) and family-based (quantitative trait locus transmission disequilibrium test) association studies of PPARGC1 and adiponectin genes. SNP in the 2 genes were genotyped. BMD was measured using dual-energy X-ray absorptiometry in the lumbar spine and hip in 401 nuclear families with a total of 1260 subjects, including 458 premenopausal women, 20-40 years of age; 401 postmenopausal women (mothers), 43-74 years of age; and 401 men (fathers), 49-76 years of age.

RESULTS

Significant within-family association was found between the Thr394Thr polymorphism in the PPGAGC1 gene and peak BMD in the femoral neck (P=0.026). Subsequent permutations were in agreement with this significant within-family association result (P=0.016), but Thr394Thr SNP only accounted for 0.7% of the variation in femoral neck peak BMD. However, no significant within-family association was detected between each SNP in the adiponectin gene and peak BMD. Although no significant association was found between BMD and SNP in the PPARGC1 and adiponectin genes in both men and postmenopausal women, haplotype 2 (T-T) in the adiponectin gene was associated with lumbar spine BMD in postmenopausal women (P=0.019).

CONCLUSION

Our findings suggest that Thr394Thr SNP in the PPARGC1 gene was associated with peak BMD in the femoral neck in Chinese women. Confirmation of our results is needed in other populations and with more functional markers within and flanking the PPARGC1 or adiponectin genes region.

Vitamin D receptor gene polymorphisms and susceptibility of hand osteoarthritis in Finnish women

We examined whether polymorphisms of the vitamin D receptor (VDR) gene was associated with individual risk of hand osteoarthritis (OA). Radiographs of both hands of 295 dentists and of 248 teachers were examined and classified for the presence of OA using reference images. The VDR ApaI and TaqI genotypes were determined by PCR-based methods. No association was observed between the VDR polymorphisms and the odds of overall hand OA. However, the carriers of the VDR t allele or At haplotype were at almost half the odds of symmetrical hand OA (odds ratio [OR] = 0.60, 95% confidence interval [CI] = 0.38–0.94 and OR = 0.59, 95% CI = 0.38–0.93, respectively) compared with the carriers of the T allele and of the non-At haplotype, respectively. Increased odds of this disease, on the contrary, was observed for women with two copies of the VDR a allele (OR = 1.93, 95% CI = 1.99–3.70) compared with women with the AA genotype. Conversely, the VDR a allele carriage was associated with a tendency of lowered odds of osteophyte (OR = 0.51, 95% CI = 0.25–1.03). When the genotype data were used to construct haplotypes, the VDR AaTt joint genotype appeared to pose a remarkably lower odds (OR = 0.26, 95% CI = 0.08–0.91) of osteophyte compared with the AAtt joint genotype. As a novel finding we observed a joint effect of a low calcium intake and VDR polymorphisms on symmetrical OA; the OR was 2.64 (95% CI = 1.29–5.40) for carriers of the aT haplotype with low daily calcium intake compared with non-carriers of the haplotype with high daily calcium intake. Our results suggest that VDR gene polymorphisms play a role in the etiology of symmetrical hand OA. Moreover, the association between the VDR gene and OA may be modified by calcium intake.

Genetic variation at the calcium-sensing receptor (CASR) locus: implications for clinical molecular diagnostics

OBJECTIVES

The calcium-sensing receptor (CASR) is critical for maintenance of blood calcium in a narrow physiologic range. Naturally occurring mutations in the calcium-sensing receptor gene (CASR) cause hypocalcaemia or hypercalcaemia, and molecular diagnosis of these mutations is clinically important. Knowledge of SNP frequency and haplotype structure is essential in understanding molecular test results.

DESIGN AND METHODS

Genotyping and haplotype analysis of 26 CASR SNPs (and a tetranucleotide insertion/deletion polymorphism) in control cohorts of Caucasian, Asian and African-American origin (n=1136, 88 and 104 chromosomes, respectively).

RESULTS

The three SNPs in exon 7 (A986S, R990G, Q1011E) are the only common exonic variants in our cohorts, and synonymous exonic SNPs are uncommon. Linkage disequilibrium analysis of the Caucasian cohort (Haploview) showed that the CASR locus is divided into three haplotype blocks, coincident with 5' regulatory, coding, and 3' regulatory domains.

CONCLUSIONS

These analyses provide an important framework for appropriate interpretation of CASR mutation screening now offered by a number of laboratories for the diagnosis of calcium disorders. They will assist in the study of CASR polymorphisms as predictors of complex disease states.

Bone health in children and adolescents after allogeneic stem cell transplantation

BACKGROUND

This cross-sectional study evaluated the overall bone health and the prevalence of vertebral complications after stem cell transplantation (SCT) in prepubertal children and adolescents.

METHODS

A total of 44 children and adolescents (median age, 10 years) were evaluated at a median of 3.8 years after SCT for areal bone mineral density (aBMD) with dual-energy X-ray absoptiometry and for vertebral fractures with instant vertebral assessment. Pretransplant and posttransplant medications and nutritional parameters were recorded, and plasma levels of vitamin D, calcium, phosphate, and parathormone were measured.

RESULTS

Of the 44 patients, 16 (36%) had a BMD Z-score of <-1.0. The patients with low BMD did not differ from the others with regard to their clinical or biochemical characteristics. Prepubertal patients had better BMD Z-scores at all sites compared with pubertal or postpubertal subjects. This was evident especially at the hip, in which the median aBMD Z-score in prepubertal patients (-0.2; range, -0.5 to +1.7) was found to be significantly higher than in pubertal (-1.1; range, -1.5 to +0.4) and postpubertal (-1.1; range, -2.6 to +0.5) patients (P = .03). Five patients (11%) had a history of peripheral fractures. Nine patients (20%) had vertebral compression fractures, which were asymptomatic in 7 patients.

CONCLUSIONS

Approximately one-third of patients who had undergone allogeneic SCT in childhood were found to have a reduced BMD before reaching adulthood. This was due in part to inadequate BMD gain during the pubertal years. The high prevalence of asymptomatic vertebral compression fractures calls for the systematic assessment of spinal health during the posttransplantation follow-up.

Association analysis of the polymorphisms of the VDR gene with bone mineral density and the occurrence of fractures

Associations of the FokI, BsmI, ApaI, and TaqI polymorphisms of the vitamin D receptor (VDR) gene with the bone mineral density (BMD) of the lumbar part of the spinal column (BMD LS) and the neck of the femur (BMD FN), and with the occurrence of fractures, were studied using the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis on DNA isolated from peripheral blood of 239 women and 40 men from the region of western Poland. Three polymorphisms of the 3' end of the VDR gene (BsmI, ApaI, TaqI) indicated a strong linkage disequilibrium. Association analysis of the VDR gene FokI polymorphism with BMD LS showed a dose effect of allele f. The association of the bAT haplotype of the BsmI, ApaI, and TaqI polymorphisms of the VDR gene with BMD FN was statistically significant. The association of the ApaI polymorphism with the occurrence of fractures was observed. Associations were also observed between the occurrence of fractures and the baT haplotypes of the VDR gene.

Relationship between adolescent amenorrhea and climacteric osteoporosis

OBJECTIVES

The relationship between climacteric osteoporosis and disturbances in menstrual cycle during adolescence was examined.

METHODS

Seven hundred and seventy-one questionnaires were shared out among women visiting the outpatient department for climacteric complaints for the first time between 2001 and 2004. Questions revealed the age, age at menarche and menopause, the regularity or irregularity of menstrual cycle during adolescence and adult ages. The bone mineral density was examined using the Dual Energy X-ray Absorptiometry (DEXA) method on the lumbar spine.

RESULTS

Six hundred and thirty-five of the 771 questionnaires were suitable for analysis. Osteoporosis was observed in 30.1% of the cases. Age, age at the menarche or at the menopause did not alter in the subgroups with or without osteoporosis. The incidence and severity of osteoporosis were significantly higher in patients reporting secondary amenorrhea during adolescent ages (42.1%; average BMD of the lumbar spine 71.6+/-3.9), as compared to the patients with normal cycle (30.4%; average BMD of the lumbar spine 84.8+/-7.8). No correlation between the occurrence of osteoporosis and the frequency of menstrual cycle during adulthood was observed.

CONCLUSIONS

Secondary amenorrhea during the years of adolescence might play a role in the development of more severe osteoporosis in menopause.

Principais causas de diminuição da massa óssea em mulheres na pré-menopausa encaminhadas ao ambulatório de doenças ósteo-metabólicas de um Hospital Terciário de Curitiba

Selecionamos mulheres pré-menopausadas com redução da DMO encaminhadas ao ambulatório de Metabolismo Ósseo do Hospital de Clínicas da UFPR, com o objetivo de definirmos o perfil destas pacientes em relação aos fatores de risco e prováveis causas secundárias de osteoporose. Trinta e quatro mulheres foram estudadas (1948 anos). Em 29 pacientes (85,3%) a coluna lombar estava acometida, 8 (23,5%) apresentaram Z-score < -2,5 e 21 (61,8%) Z-score entre -1,0 e -2,5. Vinte pacientes (58,8%) apresentaram redução da DMO em fêmur, 2 (6,2%) com Z-score < -2,5 e 18 (56,2%) com Z-score entre -1,0 e -2,5. Causa secundária foi identificada em 26 pacientes (76,5%). Este estudo demonstra que a realização de densitometria óssea é importante em mulheres na pré-menopausa com fatores de risco para redução da massa óssea, uma vez que permite o início precoce do tratamento e a prevenção das complicações relacionadas.

Vitamin D receptor polymorphisms and diseases

The vitamin D endocrine system is central to the control of bone and calcium homeostasis. Thus, alterations in the vitamin D pathway lead to disturbances in mineral metabolism. Furthermore, a role for vitamin D has been suggested in other diseases, like cancer, diabetes and cardiovascular disease. Expression and nuclear activation of the vitamin D receptor (VDR) are necessary for the effects of vitamin D. Several genetic variations have been identified in the VDR. DNA sequence variations, which occur frequently in the population, are referred to as "polymorphisms" and can have biological effects. To test whether there is a linkage between VDR polymorphisms and diseases, epidemiological studies are performed. In these studies, the presence of a variation of the gene is studied in a population of patients, and then compared to a control group. Thus, association studies are performed, and a link among gene polymorphisms and diseases can be established. Since the discovery of VDR polymorphisms a number of papers have been published studying its role in bone biology, renal diseases, diabetes, etc. The purpose of this review is to summarize the vast amount of information regarding vitamin D receptor polymorphisms and human diseases, and discuss its possible role as diagnostic tools.

Prevalence and functional significance of 25-hydroxyvitamin D deficiency and vitamin D receptor gene polymorphisms in Asian Indians

BACKGROUND

Recent studies show a wide prevalence of hypovitaminosis D in Asian Indians.

OBJECTIVE

The objective was to assess the functional significance of 25-hydroxyvitamin D [25(OH)D] deficiency, vitamin D receptor (VDR) gene, and parathyroid hormone (PTH) gene polymorphisms in relation to bone mineral density (BMD) in urban Asian Indians.

DESIGN

Serum total calcium, inorganic phosphorus, alkaline phosphatase, 25(OH)D, intact PTH, and BMD at lumbar spine, proximal femur, and forearm were measured in 105 adult subjects. The genotyping related to VDR (BsmI, FokI, and TaqI) and PTH (BstBI and DraII) gene single-nucleotide polymorphisms was carried out by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

The mean serum 25(OH)D concentration in the whole cohort was 9.8 +/- 6.0 ng/mL, which was inversely related with serum intact PTH values (P = 0.042). Ninety-nine (94.3%) of the 105 subjects had vitamin D deficiency with 25(OH)D concentrations < 20 ng/mL. The age- and body mass index (BMI)-adjusted BMD value at the hip was higher in subjects with serum 25(OH)D values > 9.0 ng/mL than in those with values < or = 9.0 ng/mL (0.893 +/- 0.114 compared with 0.839 +/- 0.112 g/cm2, respectively; P = 0.001). The mean forearm and spine BMD values in subjects with TT (VDR, TaqI) or bb (PTH, BstBI) genotypes were significantly higher than the values in subjects with Tt genotype and BB or Bb genotype, respectively.

CONCLUSION

Functionally significant 25(OH)D deficiency affecting BMD at the hip region is prevalent in urban Asian Indians. However, variation in BMD at the spine and forearm is related to VDR and PTH gene polymorphisms rather than to vitamin D status, at least in this hypovitaminotic D population.

Pubertal timing predicts previous fractures and BMD in young adult men: the GOOD study

The importance of pubertal timing for adult BMD in males was studied through association of pubertal timing with young adult bone phenotype. Pubertal timing was found to predict both cortical and trabecular volumetric BMD and previous fractures in young adult men. Thus, late puberty is a risk factor for low BMD and previous fractures in young adult men.

INTRODUCTION

Peak bone mass (PBM), achieved during puberty, is a determinant of the risk for osteoporosis and future fractures. The role of variations within the normal range in pubertal timing for fractures during pubertal development and for adult bone mass in men is unknown.

MATERIALS AND METHODS

The aim of this study was to investigate the importance of pubertal timing for adult BMD and for fractures before achievement of PBM in men. The population-based Gothenburg Osteoporosis and Obesity Determinants (GOOD) study is a well-characterized cohort of young adult Swedish males 18-20 years of age. Detailed growth charts from birth to 18-20 years of age were retrieved for 642 men participating in the GOOD study. Age at peak height velocity (PHV) was estimated and used as an assessment of pubertal timing. The skeletal phenotype was analyzed at young adult age using DXA and pQCT and previous fractures were assessed by questionnaires.

RESULTS

Age at PHV was a negative independent predictor of both adult cortical and trabecular volumetric BMD and of total body and radius areal BMD. Moreover, age at PHV was associated with previous fractures in a logistic regression analysis. The OR for cortical osteopenia was 2.49 (95% CI, 1.91-3.24; p < 0.001) and for previous upper limb fractures was 1.35 (95% CI, 1.04-1.75; p < 0.05) per year increment in age at PHV.

CONCLUSIONS

Age at PHV is a negative independent predictor of BMD and a positive predictor of previous fractures in young adult men. Longitudinal studies to determine if pubertal timing also predicts BMD and fractures in elderly men are required.

Frequency of CYP2C9 polymorphisms affecting warfarin metabolism in a large anticoagulant clinic cohort

OBJECTIVES

To assess allele frequency and genotype distribution of CYP2C9 polymorphisms in patients (n = 189) attending an anticoagulant clinic in comparison to control patients (n = 177) and also to assess if the patients with variant genotypes require lower doses of warfarin.

METHODS

Genotyping of the common CYP2C9 variants *2 and *3 was carried out by multiplexed PCR-RFLP while the *5 and *6 allele variants were genotyped by singleton PCR-RFLP. DNA sequencing was used to confirm genotype in all specimens with *3, *4 and *6 alleles.

RESULTS

CYP2C9 allele frequencies in patients were 0.81 for *1, 0.11 for *2 and 0.08 for *3, compared to 0.88, 0.08 and 0.04, respectively, in controls. Patients with *1/*3 and *X/*X (where *X is *2 or *3) genotypes required 32 to 67% less warfarin in comparison to patients with the normal *1/*1 genotype. Other alleles were observed in less than 1% of subjects.

CONCLUSIONS

Allele frequencies and genotypes for CYP2C9*2 and *3 variants in patients on warfarin are not statistically different from controls whether or not they are stratified for ethnicity. Less common genotypes (*4, *5, *6) do not contribute significantly to warfarin sensitivity among patients attending a routine anticoagulation clinic. CYP2C9 genotype predicts warfarin dosage even in an uncontrolled, retrospective survey of unselected patients on warfarin therapy.

Single-nucleotide polymorphisms and haplotypes of bone morphogenetic protein genes and peripheral bone mineral density in young Korean men and women

Bone morphogenetic proteins (BMPs) play critical roles in osteoblast differentiation. To investigate the association between common single-nucleotide polymorphisms (SNPs) of BMPs and bone mineral density (BMD), a cross-sectional study was conducted in healthy Korean men (n = 237) and women (n = 276) aged 20-39 years. Calcaneus and distal radius BMD were measured by dual energy X-ray absorptiometry. SNPs of BMP2 (-1103C > A, c.584G > A, IVS1-2744A > G, c.893T > A), BMP4 (c.712T > C, IVS1-160C > T), and BMP6 (c.1283C > G, IVS4-6838A > G, IVS5 + 24C > T) were determined using the 5'-nuclease assay. Significant associations were observed between BMP2 c.584G > A, c.893T > A genotypes and male calcaneus as well as female distal radius BMD. Men with the BMP2 c.893 AA genotype had a 16% higher BMD at the calcaneus (P for trend = 0.014), whereas women with this genotype had a 7% lower BMD at the distal radius than the other genotypes (P for trend = 0.010). A significant association was also observed between BMP4 IVS1-160C > T and male calcaneus BMD (P for trend = 0.024). When the association between haplotypes and BMD was investigated, the AAGA haplotype of BMP2 was significantly associated with low bone mass in female distal radius (P for trend = 0.013). These results suggested that one or more SNPs of BMP2 and BMP4 are associated with peripheral BMD in Korean men and women. However, this association is dependent on anatomical sites and gender. Thus, larger studies with complete coverage of SNPs are needed in the future.

A functional polymorphism in the PTHR1 promoter region is associated with adult height and BMD measured at the femoral neck in a large cohort of young caucasian women

The parathyroid hormone type 1 receptor (PTHR1) mediates the actions of parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHRP). Interacting with this receptor, PTHRP contributes to skeletal development through the regulation of chondrocyte proliferation and differentiation. Recently, a tetranucleotide repeat-(AAAG)( n )-in the P3 promoter of the PTHR1 gene has been shown to have functional activity in vitro, and homozygosity for (AAAG)(6), or the 6/6 genotype, has been associated with greater adult height compared to the 5/5 genotype. In this study, we evaluated the association of (AAAG)( n ) with height and bone mineral density (BMD) measured at lumbar spine (LS) and femoral neck (FN) in a cohort of 677 young caucasian women 18-35 years of age. Genomic DNA was amplified and genotyped by comparison with sequenced controls following electrophoretic separation through high-resolution polyacrylamide gels. Allele frequencies for (AAAG)( n ) were: 76.8% (n=5); 20.9% (n=6); 1.8% (n=7); 0.18% (n=8); 0.27% (n=9); 0.08% (n=2), and there was no evidence for Hardy-Weinberg disequilibrium. Analysis of variance showed that subjects bearing one or two (AAAG)(6) alleles (6/X & 6/6) were significantly taller (165.7+/-0.5 cm) than the others (X/X, 164.5+/-0.3 cm; P=0.034). This association was significant after adjusting for multiple covariates-current age, age at menarche, physical activity, smoking status, and intakes of caffeine and calcium. Comparison of genotype groups for BMD was not significant at LS, but BMD was significantly higher at FN in the group with at least one (AAAG)(6) allele (adjusted means: 1.021+/-0.008 vs. 0.999+/-0.006 g/cm(2), P=0.032). In conclusion, our data show that subjects bearing one or two (AAAG)(6) alleles are taller than subjects without, reinforcing the notion that in vivo variation in promoter activity of the PTHR1 gene may be a relevant genetic influence on final adult height and BMD.

Risk factors for reduced areal bone mineral density in young adults with stem cell transplantation in childhood

Slightly, but significantly, reduced bone mineral density (BMD) has been detected as a late effect after stem cell transplantation (SCT) performed in childhood. The aim of the study was to evaluate the risk factors of reduced BMD after SCT in childhood. We evaluated areal BMD of 16 young adults (six males, 10 females), aged 21 yr (range 15-34) by dual-energy X-ray absorptiometry at the lumbar spine, at the femoral neck, in the total hip, and in the total body. Bone turnover rate was evaluated by markers of bone formation and resorption. Six of the 16 patients had reduced BMD with a Z-score of < or = -1 at least at one measurement site. Factors associated with reduced BMD were prepubertal status at transplant (p = 0.03), delayed pubertal growth (p = 0.03), pubertal onset gonadal hormone insufficiency (p = 0.02), and female sex (p = 0.02). Surprisingly, height in SDs and lumbar spine BMD correlated negatively (p = 0.008) in those with reduced bone mass, indicating that low areal density could not be due the small size of the vertebrae. Bone turnover markers were similar for those with normal and reduced BMD. In conclusion, 38% of the SCT long-term survivors had reduced areal BMD. Prepubertal status at transplant with pubertal onset gonadal hormone insufficiency and female sex predisposed to reduced bone mass after SCT performed in childhood.

Bone mineral density of the proximal femur is not related to dynamic joint loading during locomotion in young women

We characterized the extent to which body mass influences the relationship between hip joint moments during locomotion and bone mineral density (BMD) of the proximal femur in healthy young women (n = 24). There is some evidence of a direct relationship between hip joint moments during locomotion and BMD of the proximal femur in patients with osteoarthritis. Nevertheless, based on expected simultaneous influences of body mass on BMD and joint moments during locomotion, we hypothesized that BMD would not be significantly associated with hip joint moments during locomotion independently of body mass. BMD of the nondominant proximal femur was determined using DXA. The hip joint moments were determined by gait analysis. The correlation between peak internal rotation moment and BMD of the intertrochanteric region was significant (r = 0.48; P = 0.019). However, body mass was significantly correlated to both BMD and the internal rotation moment (r = 0.59 and 0.70; P = 0.002 and <0.001, respectively). After accounting for the relationship between body mass and hip joint moment, the internal rotation moment was not significantly correlated to BMD of the proximal femur (r = 0.04, P = 0.34) indicating that BMD is not significantly associated with hip joint moments during locomotion independent of body mass in young healthy women.

CD38 is associated with premenopausal and postmenopausal bone mineral density and postmenopausal bone loss

One goal of osteoporosis research is to identify the genes and environmental factors that contribute to low bone mineral density (BMD) and fracture. Linkage analyses have identified quantitative trait loci (QTLs), however, the genes contributing to low BMD are largely unknown. We examined the potential association of an intronic polymorphism in CD38 with BMD and postmenopausal bone loss. CD38 resides in 4p15, where a QTL for BMD has been described. CD38-/- mice display an osteoporotic phenotype at 3 months, with normalization of BMD by 5 months. The CD38 polymorphism was identified by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis in 457 postmenopausal and 173 premenopausal Caucasian women whose spine and hip BMD was measured by dual energy X-ray absorptiometry (DXA). Influence of the CD38 polymorphism on bone loss was analyzed in 273 postmenopausal women over a follow-up of 2.94 +/- 1.50 years. The CD38-PvuII polymorphism was significantly associated with premenopausal and postmenopausal (P = 0.001) lumbar spine BMD. Women homozygous for the G allele had >14% lower spinal BMD than women with GC/CC genotypes. An allele dose effect was observed at the spine in premenopausal (P = 0.002) and postmenopausal (P < 0.001) cohorts. The CD38-PvuII polymorphism was significantly associated with femoral neck BMD in pre- and postmenopausal women (P = 0.002 and P = 0.011, respectively). However, significance was lost following adjustment of hip BMD for covariates in the postmenopausal cohort (P = 0.081). The CD38-PvuII polymorphism was weakly associated with bone loss at the spine (P = 0.024), in postmenopausal women not taking hormone replacement therapy. We suggest that the CD38-PvuII polymorphism may influence the attainment and maintenance of peak BMD and postmenopausal bone loss.

Impaired muscle strength is associated with fractures in hemodialysis patients

INTRODUCTION

Fractures are extremely common among hemodialysis (HD) patients.

METHODS

To assess if bone mineral density (BMD) and/or tests of muscle strength were associated with fractures, we studied 37 men and 15 women, 50 years and older, on HD for at least 1 year. We excluded subjects with prior renal transplants and women taking hormone replacement therapy. We inquired about low-trauma fractures since starting dialysis. Subjects underwent BMD testing with a Lunar DPX-L densitometer. Tests of muscle strength included: timed up and go (TUG), 6-min walk, functional reach, and grip strength. Lateral and thoracic radiographs of the spine were obtained and reviewed for prevalent vertebral fractures. We used logistic regression to examine associations between fracture (prevalent vertebral, self-reported low trauma since starting dialysis and/or both) and BMD, and fracture and muscle-strength tests. Analyses were adjusted for age, weight, and gender.

RESULTS

Mean age was 66+/-9.0 years, mean weight was 72.9+/-15.2 kg, and most (35 of 52) participants were Caucasian. Average duration of dialysis was 40.2 (interquartile range: 24-61.2) months. The most common cause of renal failure was diabetes (16 subjects). There were no differences by gender or fracture. Of the 52 subjects, 27 had either a vertebral fracture or low trauma fracture. There was no association between fractures, hip or spine BMD, or grip strength. In contrast, greater functional reach [odds ratio (OR) per standard deviation (SD) increase: 0.29; 95% CI: 0.13-0.69), quicker TUG (OR per SD decrease: 0.14; 95% CI: 0.11-0.23), and a greater distance walked in 6 min (OR per SD increase: 0.10; 95% CI: 0.03-0.36) were all associated with a reduced risk of fracture.

CONCLUSIONS

Impaired neuromuscular function is associated with fracture in hemodialysis patients.

Bone status of Indian women from a low-income group and its relationship to the nutritional status

Indian women from low-income groups consume diets that have inadequate calcium coupled with too few calories, proteins and micronutrients. Hospital-based data suggest that these women have osteoporotic hip fractures at a much earlier age than Western women. Studies reporting bone parameters of the Indian population involving large sample sizes are not available. This study was therefore carried out with 289 women in the 30-60-year age group to estimate the prevalence of osteoporosis and measure the bone parameters by dual energy X-ray absorptiometry (DXA). Their mean (+/- SD) age was 41.0+/-8.60 years. Their mean (+/- SD) height, weight and body mass index (BMI) were 149.1+/-5.49 cm, 49.2+/-9.85 kg and 22.1+/-3.99, respectively. Dietary intake of calcium was estimated to be 270+/-57 mg/day. The prevalence of osteoporosis at the femoral neck was around 29%. Bone mineral density (BMD) and T scores at all the skeletal sites were much lower than the values reported from the developed countries and were indicative of a high prevalence of osteopenia and osteoporosis. BMD showed a decline after the age of 35 years in cases of the lumbar spine and femoral neck. This was largely due to a decrease of bone mineral content (BMC). The nutritional status of women appears to be an important determinant of bone parameters. BMD and BMC at all the skeletal sites and whole body increased significantly with increasing body weight and BMI of women (P<0.05). However, bone area (BA) did not change with an increase in BMI. In the multiple regression analysis, apart from body weight, age, menopause and calcium intake were the other important determinants of BMD (P<0.05). In addition to these, height was also an important determinant of WB-BMC. This study highlights the urgent need for measures to improve the nutritional status, dietary calcium intake and thus the bone health of this population.

Comparison between 60 matched pairs of postmenopausal black and white women: Analysis of risk factors related to bone mineral density

PURPOSE

Osteoporosis is a systemic disease in which bone density is reduced, leading to weakness of the skeleton and increased vulnerability to fractures. The purpose of this study was to compare known or suspected risk factors (medical, gynecological, and lifestyle characteristics) related to bone loss between 60 matched pairs of black and white postmenopausal women.

METHODS

The two racial groups were matched one for one on selective anthropometric variables [age (years), standing height (cm), and body weight (kg)] in order to equate age and body size between groups. Information on risk factors was obtained from an orally administered questionnaire and body composition variables (in addition to those used for matching) assessed by anthropometry and total body dual energy X-ray absorptiometry (DXA). Four skinfold sites (chest, triceps, mid-axillary, and abdomen) were measured with Harpendon calipers and four body circumferences (chest, forearm contracted, waist, and gluteal) were assessed with a Gulick tape. DXA radius, spine, femur, and whole body measurements were obtained on a Hologic QDR-2000 with software version 7.20.

RESULTS

White women reported significantly higher proportions of alcohol use, family history of broken bones, and a greater utilization of hormones, calcium and vitamins than did black women. Black women reported a greater numbers who had other diseases (i.e., overactive thyroid, diabetes, rheumatoid arthritis, or kidney stones). Although age and body weight were similar in both groups, black women had greater lean tissue and less body fat than white women. Blacks had significantly higher bone mineral density across all body sites with the exception of the mid- and ultra-distal radius.

CONCLUSION

On the basis of these data, it was concluded that part of the difference often observed in bone density between black and white postmenopausal women might be due to lifestyle factors.

Hyperhomocysteinaemia and aortic calcification are associated with fractures in patients on haemodialysis

BACKGROUND

Fractures and atherosclerosis are common in patients with renal failure; this may be due to hyperhomocysteinemia.

AIM

To examine the relationships between fractures, vascular calcification and homocysteine levels in haemodialysis patients.

DESIGN

Cross-sectional survey.

METHODS

We enrolled 37 men and 15 women who had been on haemodialysis for at least 1 year. We identified prevalent spine fractures by radiographs. Non-spine fractures were identified by self-report and confirmed by review of radiographs or radiology reports. We classified the presence and severity of lumbar aortic calcifications with lateral lumbar radiographs. We measured serum homocysteine in all subjects within 30 days of study entry.

RESULTS

After adjusting for age and weight, increased levels of homocysteine were associated with an increased risk fracture (OR per mmol/l increase in homocysteine 1.6, 95%CI 1.2-2.0), as was the presence of aortic calcification (OR 1.6, 95%CI 1.2-2.1). Homocysteine and lumbar aortic calcification were highly correlated (r = 0.86).

DISCUSSION

Hyperhomocysteinaemia may explain the relationship between fractures and atherosclerosis in patients with renal failure.

Transforming growth factor beta-1 (TGFB1) and peak bone mass: association between intragenic polymorphisms and quantitative ultrasound of the heel

Background

Variance of peak bone mass has a substantial genetic component, as has been shown with twin studies examining quantitative measures such as bone mineral density (BMD) and quantitative ultrasound (QUS). Evidence implicating single nucleotide polymorphisms (SNPs) of the transforming growth factor beta-1 (TGFB1) gene is steadily accumulating. However, a comprehensive look at multiple SNPs at this locus for their association with indices of peak bone mass has not been reported.

Methods

A cohort of 653 healthy Caucasian females 18 to 35 years old was genotyped for seven TGFB1 SNPs. Polymorphisms were detected by restriction endonuclease digestion of amplified DNA segments.

Results

The frequencies of the least common allele at G-800A, C-509T, codon 10 (L10P), codon 25 (R25P), codon 263 (T263I), C861-20T, and 713-8 delC loci were 0.07, 0.33, 0.41, 0.08, 0.04, 0.25 and 0.01, respectively. A significant association was seen between QUS Stiffness Index (QUS-SI) and the SNP at codon 10 and the linked promoter SNP, C-509T. This association remained significant after multiple regression was used to incorporate important clinical covariates – age, BMI, level of activity, family history, and caffeine intake – into the model.

Conclusion

The association of QUS-SI with -509T is consistent with a gene-dose effect, while only individuals homozygous for the codon 10P allele showed a significant increase. In this cohort of young healthy Caucasian females, the T allele at position -509 is associated with greater bone mass as measured by calcaneal ultrasound.

Osteoporosis knowledge, beliefs, and practices among adolescent females

PURPOSE

To assess knowledge, beliefs, and practices of osteoporosis risk factors (physical activity, smoking, and nutrition) among adolescent girls.

METHODS

Questionnaires consisting of items assessing knowledge, beliefs, and practices regarding physical activity, calcium intake, and cigarette smoking were administered to 227 girls aged 12-16 years. The adolescent girls were attending public and separate schools in a small-sized Canadian city. Descriptive statistics, t-tests, and Chi-square tests were used to analyze the data.

RESULTS

Female adolescents believed that physical inactivity, smoking, and inadequate calcium were health-risking behaviors and osteoporosis risk factors, however, specific in-depth knowledge regarding these risk factors was lacking. Findings further showed that health-risking behaviors were evident, as 25% were current smokers, 58% consumed less than the adequate intake for calcium, and 52% had scores that reflected low to moderate physical activity levels.

CONCLUSION

These results highlight the need for educational interventions to promote specific osteo-protective practices among adolescent girls.

Genetic and environmental determinants of bone mineral density in Chinese women

BMD is a complex trait determined by genetic and lifestyle factors. To assess the genetic and environmental determinants of BMD in southern Chinese women, we studied a community-based cohort of 531 pre- and postmenopausal southern Chinese women and assessed the influence of 12 candidate gene loci and lifestyle risk factors on spine and hip BMD. The candidate genes studied include estrogen receptor alpha (ESR1) and beta (ESR2), calcium sensing receptor (CASR), vitamin D receptor (VDR), collagen type Ialpha1 (COLIA1), and LDL receptor-related protein 5 (LRP5). Social, medical, reproductive history, dietary habits and lifestyle factors were determined using a structured questionnaire. Single nucleotide polymorphisms (SNPs) of the COLIA1 and LRP5 gene in Chinese were determined by direct sequencing. Nucleotide (nt) -1363C/G and -1997 G/T of COLIA1, nt 266A/G, 2220C/T and 3989C/T of LRP5 gene were analyzed. Using stepwise multiple linear regression analyses, body weight was the strongest predictor for BMD in premenopausal women (n = 262), which accounted for 15.9% of the variance at the spine, 20% at femoral neck, 17.1% at trochanter, 24.3% at total hip and 10.9% at the Ward's triangle. Other significant predictors were ESR1 Ivs1-397T/C genotype (2.2% at the spine); LRP5 2220C/T genotype (1.3% at the spine, 1.6% at the trochanter); LRP5 266A/G genotype (1.1% at Ward's triangle); age at menarche (1.3% at trochanter) and age (2.0% at Ward's triangle). As for postmenopausal women (n = 269), body weight ( approximately 25% at various sites) and age (approximately 16% at femoral neck, trochanter, total hip and Ward's triangle sites) were the strongest predictors of BMD. Other significant predictors were age at menarche (4.4% at spine, 0.7% at femoral neck, 1.4% at trochanter, and 1.4% at Ward's triangle); weight bearing physical activity (2.1% at trochanter and 1% at total hip); calcium intake (1.1% at femoral neck, 0.9% at trochanter, and 1.7% at total hip) ; height (0.7% at trochanter); and ESR2 1082A/G genotype (0.8% at trochanter). We conclude that BMD at various sites and at different time span of a woman is modified by different genetic and lifestyle factors, suggesting that BMD is highly dependent on gene-environmental interactions.

Loci for regulation of bone mineral density in men and women identified by genome wide linkage scan: the FAMOS study

Osteoporosis is a common disease with a strong genetic component, characterized by reduced bone mass and an increased risk of fracture. Bone mineral density (BMD) is a highly heritable trait and a key determinant of osteoporotic fracture risk, but the genes responsible are incompletely defined. Here, we identified quantitative trait loci (QTL) for regulation of BMD by a genome wide scan involving 3691 individuals from 715 families, who were selected because of reduced BMD values at the lumbar spine (LS-BMD) or femoral neck (FN-BMD) in probands. Linkage analysis was conducted in the study group as a whole with correction for age, gender, weight and height. Further analyses were conducted for men and women separately to identify gender-specific QTL and for those under and over the age of 50 years to distinguish QTL for peak bone mass from those that influence bone mass in older people. No regions of suggestive or significant linkage were identified when data from all subjects were analyzed together. On subgroup analysis, however, we identified a significant QTL for FN-BMD on chromosome 10q21 (LOD score +4.42; men < or =50 years) and two suggestive QTL for LS-BMD on chromosomes 18p11 (LOD score +2.83; women >50 years) and 20q13 (LOD score +3.20; women < or =50 years). We identified five other QTL for BMD with LOD scores of greater than +2.20 on chromosomes 3q25, 4q25, 7p14, 16p13 and 16q23. This study provides evidence for gender-specific, site-specific and age-specific QTL, which regulate BMD in humans, and illustrates the importance of conducting subgroup analysis to detect these loci.

Effects of pubertal development, height, weight, and grip strength on the bone mineral density of the lumbar spine and hip in peripubertal Japanese children: Kyoto kids increase density in the skeleton study (Kyoto KIDS study)

The effects of growth and pubertal development on the bone mineral density (BMD) of the lumbar spine and hip in peripubertal Japanese children were studied as a basis for evaluating the effects of modifiable factors on bone mass gain. The study comprised bone mass measurements in the lumbar spine (L2-4), femoral neck, and total hip using dual-energy X-ray absorptiometry as well as body size measurements and detailed interviews on medical history and pubertal status. The subjects were 404 first-grade students in three junior high schools (129 boys and 275 girls, mean age 12.8 +/- 0.3 years) with no diseases or medication that would affect bone metabolism. BMD at each site showed an increasing trend with physical growth and sexual maturity. Significant positive correlations were observed between BMD at every skeletal site and height, weight, and grip strength in pre- and postpubertal boys and girls. In multiple regression analyses, pubertal development had a significant positive independent effect on BMD at every skeletal site in girls, but not in boys. Physical and pubertal development showed major effects on BMD, but the magnitude of these effects differed in boys and girls, even if they were of the same age. We conclude that confounding factors due to physical and pubertal development should be taken into consideration in different ways for boys and girls in investigations on the effects of environmental or behavioral factors on bone mass acquisition in peripubertal children.

Effect of acute oral calcium load on serum PTH and bone resorption in young healthy subjects: an overnight study

OBJECTIVE

To investigate the effects of a 400 mg acute oral calcium dose on PTH and bone resorption markers in a young, healthy population.

DESIGN

Fasting serum parathyroid hormone (PTH), C-telopeptides (CTX), total calcium (Ca), albumin and urinary calcium/creatinine ratio (uCa/Cr) were measured on two separate days: one before and the other 10 h after oral administration of 400 mg calcium. Serum 25-hydroxy vitamin D (25-OHD) status was assessed at baseline. Dietary calcium intake was assessed using a food frequency questionnaire (FFQ).

SUBJECTS

A total of 32 healthy, young adults (17 female, 15 male; mean+/-s.e.m. age: 21+/-1 y) took part in this study. Their mean (s.e.m.) calcium intake was 1125 (+/-56) mg/day.

INTERVENTION

Effervescent Sandocal 400 tablets dissolved in water.

RESULTS

After the calcium challenge, mean Ca and uCa/Cr ratio increased significantly, and both PTH and CTX concentrations were significantly lower. Multiple regression analysis showed no relationship between the response to the 400 mg load and previous dietary calcium intake (as assessed by FFQ) or serum 25-OHD.

CONCLUSION

We have shown that in a young, healthy population, 400 mg oral calcium can inhibit bone resorption (as measured by serum CTX) and PTH, and this appears to be independent of previous dietary calcium intake and vitamin D status.

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

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

Vitamin D receptor gene polymorphisms in relation to Vitamin D related disease states

The role in skeletal metabolism of the steroid hormone Vitamin D and its nuclear receptor (VDR) is well known. In addition, however, Vitamin D is also involved in a wide variety of other biological processes including modulation of the immune response and regulation of cell proliferation and differentiation. Variations in the Vitamin D endocrine system have thus been linked to several diseases, including osteoarthritis, diabetes, cancer, cardiovascular disease and tuberculosis. Evidence to support this pleiotropic character of Vitamin D has included epidemiological studies on circulating Vitamin D hormone levels, but also genetic epidemiological studies. Genetic studies provide excellent opportunities to link molecular insights with epidemiological data and have therefore gained much interest. DNA sequence variations which occur frequently in the population are referred to as "polymorphisms" and are usually suspected of having only modest and subtle effects. Recent studies have indicated many polymorphisms to exist in the VDR gene, but the influence of VDR gene polymorphisms on VDR protein function are largely unknown. Sofar, three adjacent restriction fragment length polymorphisms (RFLP) for BsmI, ApaI and TaqI, respectively, at the 3' end of the VDR gene have been the most frequently studied sofar. But because these polymorphisms are probably non-functional, linkage disequilibrium (LD) with one or more truly functional polymorphisms elsewhere in the VDR gene is assumed to explain the associations observed. Research is therefore focussed on documenting additional polymorphisms across the VDR gene to verify this hypothesis, and on trying to understand the functional consequences of the variations. Substantial progress has been made including the discovery of novel polymorphisms in the large promoter region of the VDR gene. Eventually, results of this research will deepen our understanding of variability in the Vitamin D endocrine system and might find applications in risk-assessment of disease and in predicting response-to-treatment.

Association between Vitamin D receptor polymorphisms and the rate of bone loss in elderly women-importance of adjusting for dietary and lifestyle factors

The association between the restriction length polymorphisms of the Vitamin D receptor (VDR) gene and the bone mineral density (BMD) or the rate of bone loss is still under debate. In a longitudinal study of untreated postmenopausal elderly women, we evaluated the relationship between the VDR gene polymorphisms (BsmI, TaqI, ApaI, and FokI) and the rate of bone loss over a 3-year period. We also examined the effect of adjustments for dietary and lifestyle factors on these associations. Before adjustments, the rate of femoral neck bone loss was - 3.76 +/- 1.58% in women with BB genotype and 0.45 +/- 0.65% in women with bb genotype, which was not significantly different. Upon adjustment for dietary and lifestyle factors, statistically significant (P = 0.03) bone loss was observed at femoral neck in women with BB genotype (- 3.66 +/- 2.44%) compared to that of bb genotype (2.39 +/- 1.32%). Similar results were observed with TaqI genotypes. The rates of bone loss at other skeletal sites were not different between VDR genotypes defined by BsmI and TaqI. VDR gene polymorphisms defined by ApaI and FokI were not related to the rate of bone loss.

Dynamic loads are determinants of peak bone mass

This study investigated the association between non-invasive measurements of bone mass and markers of dynamic and static hip joint loads in subjects expected to be at peak bone mass. The bone mineral density (BMD) and bone mineral content (BMC) of three proximal femoral sites (neck, greater trochanter, and total) were measured by dual energy X-ray absorptiometry, and the peak external joint moments at the hip during walking and jogging were calculated from gait analyses of 31 normal human subjects ranging in age from 30 to 49 years (18 females, 13 males). Various multiple regression analyses were performed to determine how much of the variance in BMD and BMC was explained by height, body mass, and the peak hip joint moments. In total, the models explained up to 40% of the variance in BMD and 58% of the variance in BMC. Inclusion of height or body mass did not increase the explanatory power of the models for BMD and explained no more than 8% of the total variance in BMC once the joint moments from walking were allowed to enter the models. These data support the hypothesis that variance in peak bone mass is associated with variance in dynamic hip loads largely independent of the effect of static factors such as height and body mass.

Meta-analysis of molecular association studies: vitamin D receptor gene polymorphisms and BMD as a case study

With the rise of molecular and genetic epidemiology, molecular association studies are increasingly common; however, meta-analysis of these studies has been a neglected area. This study performed a meta-analysis of the association of the vitamin D receptor (VDR) gene polymorphisms and BMD. We also highlight methodological issues that need to be resolved.

INTRODUCTION

With the rise of molecular and genetic epidemiology, molecular association studies are increasingly common; however, meta-analysis of these studies has been a neglected area. This study performed a meta-analysis of the association of vitamin D receptor (VDR) gene polymorphisms and BMD/osteoporosis and highlights methodological issues.

MATERIALS AND METHODS

Studies published from 1994 to 2001 were identified through Medline using PubMed software. The reference lists of the articles retrieved were also reviewed. Where eligible papers had insufficient information, we contacted authors by mail (up to three mailings) for additional information. Any observational study, which tested the association between VDR BsmI genotypes and either BMD or osteoporosis at the femoral neck or spine in adult women, was included in the review. Data were extracted independently by two reviewers (AT and JA) using a standardized data extraction form.

RESULTS

The B allele was significantly associated with BMD at the spine; it seemed to follow a recessive model, with the BB genotype having lower BMD than Bb/bb genotypes at baseline, which led to greater bone mineral loss over time. Highlighted methodological lessons included the need to check Hardy-Weinberg equilibrium and the importance of exploring heterogeneity, pooling data in a manner that is sensitive to genetic models, and avoiding multiple comparisons.

CONCLUSION

With the proliferation of molecular association studies, there will be an increased need to quantify the magnitude of the risk associated with genetic polymorphisms. This will likely entail meta-analytic methods, and this meta-analysis highlights some of the methodological issues that will need to be resolved.

Fruit and vegetable intakes are an independent predictor of bone size in early pubertal children

BACKGROUND

Adequate intakes of fruit and vegetables are recommended for optimum health in children.

OBJECTIVE

The objective of this study was to determine whether consuming fruit and vegetables >3 times per day is beneficial to bone mass in children.

DESIGN

Fifty-six white females (Tanner stage 2) recorded dietary intake on 3 independent days. The numbers of servings of fruit and vegetables were recorded for each day and tallied, and the subjects were divided into 2 consumption groups for analysis (low consumption: <3 servings/d, n = 22; high consumption: > or = 3 servings/d, n = 34). Bone area and the bone mineral content of the whole body and radius were assessed by using dual-energy X-ray absorptiometry. Radioimmunoassays measured serum parathyroid hormone and 25-hydroxyvitamin D. Twenty-four-hour urine samples were assessed for calcium, sodium, and creatinine.

RESULTS

After adjustment for age, body mass index, and physical activity, those children who reported consuming > or = 3 servings fruit and vegetables/d had more bone area of the whole body (6.0%; P = 0.03) and radius (8.3%; P = 0.03), lower urinary calcium excretion (2.6 +/- 0.2 compared with 1.8 +/- 0.3 mg/kg; P = 0.04), and lower parathyroid hormone (19.6 +/- 1.9 compared with 25.0 +/- 1.6 pg/mL; P = 0.01) than did those children who reported consuming <3 servings fruit and vegetables/d.

CONCLUSIONS

High fruit and vegetable intakes have beneficial effects on the bone area of the radius and whole body in early pubertal girls. The lower urinary calcium output associated with higher fruit and vegetable intakes may be a modulating factor.

Population-based differences in frequency of the transcobalamin II Pro259Arg polymorphism

OBJECTIVE

A common polymorphism of the transcobalamin II (TC-II) gene, Pro250Arg, has been implicated as a possible genetic factor in population-based differences in vitamin B(12) metabolism. Our objective was to determine whether the prevalence of TC-II Pro259Arg polymorphism differs significantly between Caucasian, Asian and African-American groups.

METHODS

Genomic DNA was available on 187 Caucasians and 43 Asians from the Toronto area, and 51 African-Americans from Northeastern United States. A mutagenically separated PCR method was employed to genotype these groups for the TC-II Pro259Arg polymorphism (776C-->G).

RESULTS

The frequency of the Arg 259 allele varied significantly among the three groups studied (0.439 in Caucasian, 0.558 in Asian and 0.363 in African; P = 0.022). The Asian group had a significantly higher frequency of the Arg 259 allele compared to the Caucasian (P = 0.030) and the African-American group (P = 0.006). The frequency of the Arg 259 allele in the Caucasian and African-American groups was not significantly different (P = 0.103).

CONCLUSION

Population-based differences in TC-II Pro259Arg frequency are significant and could be a contributor to ethnic variation in susceptibility to vitamin B(12) deficiency, a common and persistent problem.

Peak bone mineral area density and determinants among females aged 9 to 24 years in Mexico

INTRODUCTION

Peak bone mineral area density is the amount of bone tissue present when skeletal maturation is completed. The exact age at which bone accumulation reaches a plateau varies with skeletal region. In Mexico and other Latin American countries, there are very few reports on bone mineral area density at early age.

MATERIAL AND METHODS

A cross-sectional study of 461 females between 9 and 24 years of age in Cuernavaca, Mexico, distributed proportionately by age group, determined the bone mineral density (BMD) in femur, lumbar spine, and subcranial skeleton, using a Hologic 4500-Series A osteodensitometer. The peak bone mineral area density (PBM) was determined by using the sigmoid growth model defined by Raymond-Pearl (CSRP). Cohort comparisons among different age groups were developed to evaluate BMD in three skeletal regions, with the Dunnett test, comparing the slopes of BMD by each age stratum. Also, the primary determinants of BMD were evaluated through models of multiple linear regression.

RESULTS

The timing of PBM is highly site specific with some skeletal regions reaching PBM earlier: beginning with the femur, and later reaching the lumbar spine and subcranial skeleton. Using a multivariate model, age and body weight were important predictors of BMD in the three anatomical regions studied ( p<.001). The percentage of fat is associated in an inversely proportionate manner ( p<.005), as independent predictors for BMD in the lumbar spine. The age of the onset of menstruation is also a predictor of BMD in the lumbar spine ( p<0.05); vigorous activity is an important predictor in the subcranial skeleton ( p<0.001).

DISCUSSION

For Mexican females in the state of Morelos, the BMD are similar to that reported in a number of ethnic groups. In mestizo females the timing of PBM is highly site specific with some skeletal regions acquiring PBM earlier: specifically, in the femoral region where PBM rapidly reached a plateau. In Mexico, early strategies for preventing osteoporosis should be focused on promoting physical activity and appropriate eating habits (control of obesity, among others) during the puberty stage.

Meta-analysis of COL1A1 Sp1 polymorphism in relation to bone mineral density and osteoporotic fracture

Genetic factors play an important role in the pathogenesis of osteoporosis and several candidate gene polymorphisms have been implicated in the regulation of this process. One of the most widely studied is the Sp1 binding site polymorphism in the COL1A1 gene. This polymorphism has been associated with BMD and osteoporotic fracture in several studies, but the data from different studies have been conflicting. Here we have attempted to clarify the association between COL1A1 Sp1 alleles, BMD, and osteoporotic fracture by conducting a meta-analysis of 26 published studies including 7849 participants. Under a fixed effects model, BMD values at the lumbar spine (6800 subjects) were significantly lower in the "Ss" genotype group when compared with "SS" homozygotes (standardized mean difference = 0.131 [95% CI, 0.06,0.16], P = 0.00005) but the difference was not significant for the "ss" comparison (0.09 [-0.03,0.21], P = 0.13). At the femoral neck (6750 subjects) BMD values were lower in the "Ss" genotype (0.14 [0.08,0.19], P < 0.00001) and lower still in the "ss" genotype group (0.19 [0.07,0.31], P = 0.001). Similar results were found when the data were analyzed under a random effects model. Analysis of fracture data (6961 subjects) showed an increased odds ratio for any fracture in "Ss" subjects (1.26 [95% CI 1.09,1.46], P = 0.002) and an even greater increase in "ss" subjects (1.78 [1.30,2.43], P = 0.0003). Subgroup analysis showed that increased risk was largely attributable to vertebral fracture where the odds ratio was 1.37 [1.15,1.64] for "Ss" (P = 0.0004) and 2.48 [1.69,3.65] for "ss" (P < 0.00001). The risk of nonvertebral fracture was not increased in relation to the COL1A1 genotype, although power to detect an effect was limited by the fact that fewer studies had analyzed nonvertebral fracture. We conclude that the COL1A1 Sp1 alleles are associated with a modest reduction in BMD and a significant increase in risk of osteoporotic fracture, particularly vertebral fracture.

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.