Strong Genetic Effects on Bone Mineral Density in Multiple Locations with Two Different Techniques: Results from a Cross-Sectional Twin Study

Choose your mother wisely: the familial resemblance of bone adaptation

This study demonstrates how complex bone microarchitectural features can be summarized to describe bone adaptations seen with aging in women, which are consistent with the stages of osteoporosis. Additionally, we showed familial resemblance in these bone microarchitectural traits between mothers and daughters that can be used to predict bone adaptations.

INTRODUCTION

Patient-specific characterization of bone quality can reduce complex microarchitectural features to common combinations of bone characteristics, known as bone phenotypes. This study investigated whether there is a general trend in bone phenotype change over time seen with aging in females and whether there is a familial resemblance to phenotype membership between mothers and daughters.

METHODS

Bone phenotype membership was calculated on biological mother and daughter pairs (Participants = 101), scanned using high resolution peripheral quantitative computed tomography, to the three pre-defined phenotypes (healthy, low volume, and low density). The trajectory of bone phenotype with age was explored using all participant's data. Linear regression models were used to assess the familial resemblance of phenotyping in the mother-daughter pairs.

RESULTS

When stratified for age, the trajectory of the phenotype membership transitioned from healthy (20-40 years), to low volume (40-60 years), to low density (60-80 years), which similarly aligns with the stages of osteoporosis observed in females. Familial resemblance (½h2) was observed in the healthy phenotype (β = 0.432, p < 0.01). Predictive modelling showed a significant association in phenotype membership between mothers and daughters in the healthy (R2 = 0.347, p = 0.04) and low volume (R2 = 0.416, p < 0.01) phenotypes, adjusted for age, height, and weight.

CONCLUSION

Our results suggest that phenotype membership in females changes with age in a pattern that is consistent with the stages of osteoporosis. Additionally, we showed familial resemblance in bone phenotype, which can be used to predict bone adaptations between mothers and daughters that are associated with bone loss with aging.

Genetic and environmental determinants of bone quality: a cross-sectional analysis of the Hungarian Twin Registry

There is abundant evidence that bone mineral content is highly heritable, while the heritability of bone quality (i.e. trabecular bone score [TBS] and quantitative ultrasound index [QUI]) is rarely investigated. We aimed to disentangle the role of genetic, shared and unique environmental factors on TBS and QUI among Hungarian twins. Our study includes 82 twin (48 monozygotic, 33 same-sex dizygotic) pairs from the Hungarian Twin Registry. TBS was determined by DXA, QUI by calcaneal bone ultrasound. To estimate the genetic and environmental effects, we utilized ACE-variance decomposition. For the unadjusted model of TBS, an AE model provided the best fit with > 80% additive genetic heritability. Adjustment for age, sex, BMI and smoking status improved model fit with 48.0% of total variance explained by independent variables. Furthermore, there was a strong dominant genetic effect (73.7%). In contrast, unadjusted and adjusted models for QUI showed an AE structure. Adjustments improved model fit and 25.7% of the total variance was explained by independent variables. Altogether 70-90% of the variance in QUI was related to additive genetic influences. We found a strong genetic heritability of bone quality in unadjusted models. Half of the variance of TBS was explained by age, sex and BMI. Furthermore, the adjusted model suggested that the genetic component of TBS could be dominant or an epistasis could be present. In contrast, independent variables explained only a quarter of the variance of QUI and the additive heritability explained more than half of all the variance.

A Comprehensive Analysis of Bone Mineral Density Changes across the Lifespan: Insights from National Surveys

BACKGROUND

There is limited research providing an overall understanding of bone mineral density (BMD) changes throughout different stages of life. This study aimed to investigate the pattern of BMD changes across childhood, adolescence, adulthood, and old age, as well as exploring the critical time of peak BMD (PBMD).

METHODS

Participants of three major ethnicities from National Health and Nutrition Examination Survey 1999 to 2018 were involved: 46,381 and 20,944 participants aged 8-85 years old were included in the Lumbar spine BMD (LSBMD) and femoral neck BMD (FNBMD) studies, respectively. BMD was measured using dual-energy X-ray absorptiometry. The generalized additive model was used to construct smoothed percentile curves.

RESULTS

Both males and females experienced a sharp increase in LSBMD during puberty, with females reaching their PBMD earlier than males. Females' LSBMD remained higher than males' before the age of approximately 50, except for Non-Hispanic Blacks. For males, LSBMD reached a plateau at around 30 years old after reaching the peak value. Females exhibited two peak points on the fitted curves, with the second PBMD occurring around 36-37 years old. Ethnic variations were observed, with Non-Hispanic Blacks displaying the highest BMD levels at all ages. Non-Hispanic Whites and Mexican Americans had lower BMD levels, with Mexican Americans generally exhibiting the lowest BMD. FNBMD reached its peak earlier than LSBMD, and males consistently had higher FNBMD than females.

CONCLUSIONS

This nationally representative study contributes to the understanding of BMD changes across the lifespan, and might provide guidance for bone health interventions in different population groups.

Genetic Evaluation for Monogenic Disorders of Low Bone Mass and Increased Bone Fragility: What Clinicians Need to Know

PURPOSE OF REVIEW

The purpose of this review is to outline the principles of clinical genetic testing and to provide practical guidance to clinicians in navigating genetic testing for patients with suspected monogenic forms of osteoporosis.

RECENT FINDINGS

Heritability assessments and genome-wide association studies have clearly shown the significant contributions of genetic variations to the pathogenesis of osteoporosis. Currently, over 50 monogenic disorders that present primarily with low bone mass and increased risk of fractures have been described. The widespread availability of clinical genetic testing offers a valuable opportunity to correctly diagnose individuals with monogenic forms of osteoporosis, thus instituting appropriate surveillance and treatment. Clinical genetic testing may identify the appropriate diagnosis in a subset of patients with low bone mass, multiple or unusual fractures, and severe or early-onset osteoporosis, and thus clinicians should be aware of how to incorporate such testing into their clinical practices.

Bone mineral density and the risk of incident dementia: A meta-analysis

BACKGROUND

It is not known whether bone mineral density (BMD) measured at baseline or as the rate of decline prior to baseline (prior bone loss) is a stronger predictor of incident dementia or Alzheimer's disease (AD).

METHODS

We performed a meta-analysis of three longitudinal studies, the Framingham Heart Study (FHS), the Rotterdam Study (RS), and the Rush Memory and Aging Project (MAP), modeling the time to diagnosis of dementia as a function of BMD measures accounting for covariates. We included individuals with one or two BMD assessments, aged ≥60 years, and free of dementia at baseline with follow-up available. BMD was measured at the hip femoral neck using dual-energy X-ray absorptiometry (DXA), or at the heel calcaneus using quantitative ultrasound to calculate estimated BMD (eBMD). BMD at study baseline ("baseline BMD") and annualized percentage change in BMD prior to baseline ("prior bone loss") were included as continuous measures. The primary outcome was incident dementia diagnosis within 10 years of baseline, and incident AD was a secondary outcome. Baseline covariates included age, sex, body mass index, ApoE4 genotype, and education.

RESULTS

The combined sample size across all three studies was 4431 with 606 incident dementia diagnoses, 498 of which were AD. A meta-analysis of baseline BMD across three studies showed higher BMD to have a significant protective association with incident dementia with a hazard ratio of 0.47 (95% CI: 0.23-0.96; p = 0.038) per increase in g/cm2 , or 0.91 (95% CI: 0.84-0.995) per standard deviation increase. We observed a significant association between prior bone loss and incident dementia with a hazard ratio of 1.30 (95% CI: 1.12-1.51; p < 0.001) per percent increase in prior bone loss only in the FHS cohort.

CONCLUSIONS

Baseline BMD but not prior bone loss was associated with incident dementia in a meta-analysis across three studies.

Heel bone mineral density and various oral diseases: a bidirectional Mendelian randomization

INTRODUCTION

Observational studies demonstrated that the relationship between bone mineral density and oral diseases is mixed. To access the association between heel bone mineral density and various oral diseases, we conducted the Mendelian randomization analysis to explore the association.

MATERIALS AND METHODS

Two-sample bidirectional Mendelian analysis was used to explore the relationship between heel bone mineral density and various oral diseases. The inverse-variance weighted (IVW) was used as the primary effect estimate, and various methods were applied to test the reliability and stability of the results, namely MR-Egger, weighted median, simple mode, and weighted mode.

RESULTS

This study showed that there was a negative relationship between heel BMD and periodontitis when heel BMD was used as an exposure factor and periodontitis as an outcome factor (IVW OR = 0.85; 95% CI, 0.75-0.95; p = 0.005). Bidirectional Mendelian randomization showed that there was no statistically significant association between periodontitis and heel bone mineral density when chronic periodontitis was the exposure factor (p > 0.05). And there was no significant relationship between heel bone mineral density and other oral diseases (dental caries, diseases of pulp and periapical tissues, impacted teeth, cleft lip, and cleft palate, oral and oropharyngeal cancer) (p > 0.05).

CONCLUSION

This study showed that there was a negative relationship between heel bone density and periodontitis, and the decrease in heel bone density could promote the occurrence of periodontitis. In addition, there was no statistically significant relationship between heel bone density and other oral diseases.

Utilizing Graphical Analysis of Chest Radiographs for Primary Screening of Osteoporosis

Background and Objectives: Osteoporosis is a major risk of fractures, harming patients’ quality of life. Dual-energy X-ray absorptiometry (DXA), which can detect osteoporosis early, is too expensive to be conducted on a regular basis. Therefore, we aimed to evaluate a screening method using chest radiographs developed in Japan applied to another population. Materials and Methods: Fifty-five patients who had a chest radiograph and DXA and applied within three months of each test were recruited from the patient database of Semmelweis University (Budapest, Hungary). Graphical analysis of the chest radiographs was conducted to identify the ratio of the cortical bone in the clavicle of each patient. Two researchers performed the analysis, and multiple regression was conducted to determine the bone mineral density of each patient provided by DXA. Results: The Pearson correlation between two examiners’ determinations of the cortical bone ratio was 0.769 (p < 0.001). The multiple regression model proved to be statistically significant in identifying osteoporosis, but the model adopted for the Hungarian population was different compared to the Japanese population. Conclusions: This simple, economic Japanese graphical analysis method for chest radiographs may be feasible in detecting osteoporosis. Further studies with a larger population of patients with greater variety of ethnicity would be of value in improving the accuracy of this model.

The Impact of Environmental and Genetic Factors on Bone Quality in Monozygotic and Dizygotic Twins

The purpose of the research was to assess the genetic and environmental influences on bone properties. One hundred thirty-two pairs of twins (99/33 monozygotic/dizygotic) underwent anthropometric measurements and phalangeal quantitative ultrasound (DBM Sonic 1200, Igea, Italy) measuring the amplitude speed of sound (AD-SoS, m/s). The mean age was 16.78 ± 12.35 years for monozygotic twins and 14.30 ± 8 years for dizygotic. Interpair and intrapair correlations between twins were calculated. In the groups of monozygotic and dizygotic twins, Ad-SoS correlated significantly with age (r = 0.56−0.73, p < 0.05), weight (r = 0.73−0.78, p < 0.05), and height (r = 0.80−0.81, p < 0.05). The strongest intrapair correlation (r = 0.99−0.998) was noted in monozygotic females for Ad-SoS, weight, and height. There was a statistically significant correlation between the intrapair difference of Ad-SoS and age but only in the groups of monozygotic and dizygotic females (r = 0.281, r2 = 0.079, and p = 0.028; r = 0.544, r2 = 0.296, and p = 0.01, respectively). After age adjustment, it was estimated that 28.62% of Ad-SoS in women and 13.2% of Ad-SoS in men was explained by genetic influence, leading to the conclusion that Ad-SoS changed with age, weight, and height. The strongest correlation between pairs of twins was observed in monozygotic twins. The differences in bone values between female twins arose with age, which indicated the role of environmental factors.

Comparison of the Coincidence of Osteoporosis, Fracture, Arthritis Histories, and DEXA T-Score between Monozygotic and Dizygotic Twins: A Cross-Sectional Study Using KoGES HTS Data

We explored the genetic and environmental inter-relationships among osteoporosis, fracture, arthritis, and bone mineral density concordance in monozygotic twins compared to those in dizygotic twins. This cross-sectional research assessed data of 1032 monozygotic and 242 dizygotic twin pairs aged >20 years included in the Healthy Twin Study data of the Korean Genome and Epidemiology Study between 2005 and 2014. Outcomes of interest included illness concordance and absolute differences in dual-energy X-ray absorptiometry (DEXA) T-scores. We found comparable concordances of osteoporosis, fractures, osteoarthritis, and rheumatoid arthritis between monozygotic and dizygotic twins. Medical histories of osteoporosis, fractures caused by accident or falling, osteoarthritis, and rheumatoid arthritis were not distinct between monozygotic and dizygotic twins. Accidental fracture occurrence in both monozygotic twins showed significantly lower odds than that in dizygotic twins. Genetic influence on liability to fracture risk might thus be maintained. DEXA T-scores for bone mineral density indicated more comparable tendencies within monozygotic twin pairs than within dizygotic ones, suggesting the relative importance of genetic contribution to bone mineral density. The relative importance of genetic factors in bone mineral density is sustained between monozygotic twins; overt disease expression of osteoporosis, fractures, or arthritis may be affected by environmental factors.