Genetic influence on bone mineral density in Korean twins and families: the healthy twin study

Demystifying the Risk Factors and Preventive Measures for Osteoporosis

Background

Osteoporosis is a major health problem, globally. It is characterized by structural bone weakness leading to an increased risk of fragility fractures. These fractures commonly affect the spine, hip and wrist bones. Consequently, Osteoporosis related proximal femur and vertebral fractures represent a substantial, growing social and economic burden on healthcare systems worldwide. Indentification of the risk factors, clinical risk assessment, utilization of risk assessment tools and appropriate management that play a crucial role in reducing the burden of Osteoporosis by tackling modifiable risk factors.

Methods

This chapter explores various risk factors that are associated with Osteoporosis and provides an overview of various clinical and diagnostic risk assessment tools with a particular emphasis on evidence-based strategies for their prevention.

Conclusion

The role of emerging technologies such as Artificial Intelligence (AI) and perspectives such as newer diagnostic modalities, monitoring and surveillance approaches in prevention of risk factors in the pathogenesis of Osteoporosis is highlighted.

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.

The relationship between thoracic kyphosis and age, and normative values across age groups: a systematic review of healthy adults

Background

Thoracic kyphosis is reported to increase with ageing. However, this relationship has not been systematically investigated. Peoples’ kyphosis often exceeds 40°, but 40° is the widely accepted cut-off and threshold for normality. Consequently, patients may be misclassified. Accurate restoration of kyphosis is important to avoid complications following spinal surgery. Therefore, specific reference values are needed. The objective of the review is to explore the relationship between thoracic kyphosis and age, provide normative values of kyphosis for different age groups and investigate the influence of gender and ethnicity.

Methods

Two reviewers independently conducted a literature search, including seven databases and the Spine Journal, from inception to April 2020. Quantitative observational studies on healthy adults (18 years of age or older) with no known pathologies, and measuring kyphosis with Cobb’s method, a flexicurve, or a kyphometer, were included. Study selection, data extraction, and study quality assessment (AQUA tool) were performed independently by two reviewers. The authors were contacted if clarifications were necessary. Correlation analysis and inferential statistics were performed (Microsoft Excel). The results are presented narratively. A modified GRADE was used for evidence quality assessment.

Results

Thirty-four studies (24 moderate-quality, 10 high-quality) were included (n = 7633). A positive moderate correlation between kyphosis and age was found (Spearman 0.52, p < 0.05, T5-T12). Peoples’ kyphosis resulted greater than 40° in 65% of the cases, and it was significantly smaller in individuals younger than 40 years old (x < 40) than in those older than 60 years old (x > 60) 75% of the time (p < 0.05). No differences between genders were found, although a greater kyphosis angle was observed in North Americans and Europeans.

Conclusion

Kyphosis increases with ageing, varying significantly between x < 40 and x > 60. Furthermore, kyphosis appears to be influenced by ethnicity, but not gender. Peoples’ thoracic sagittal curvature frequently exceeds 40°.

Trial registration

The review protocol was devised following the PRISMA-P Guidelines, and it was registered on PROSPERO (CRD42020175058) before study commencement.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02592-2.

Comparing proton pump inhibitors with histamin-2 receptor blockers regarding the risk of osteoporotic fractures: a nested case-control study of more than 350,000 Korean patients with GERD and peptic ulcer disease

Background

Patients with peptic ulcer disease (PUD) and gastroesophageal reflux disease (GERD) are more likely to receive long-term therapy with proton pump inhibitors (PPIs). This study aimed to investigate the risk of osteoporotic fractures in PPI users compared to histamine-2 receptor antagonist (H2RA) users and the association between fractures and the duration and regular use of PPI.

Methods

A population-based, nationwide nested case-control study from January 2006 to December 2015 was performed using Korean National Health Insurance Service claims data. We included patients ≥50 years of age, without previous fractures, newly prescribed with PPI or H2RA, and diagnosed with PUD or GERD from 2006 to 2015. Patients with osteoporotic fracture (n = 59,240) were matched with the non-fracture control group (n = 296,200) at a 1:5 ratio based on sex, age, cohort entry date, follow-up duration, and bisphosphonate use. The osteoporotic fractures were defined using the diagnostic codes of claims data (M80, M81, M82, M484, M485, S220, S221, S320, S327, S422, S423, S525, S526, S72).

Results

The higher the cumulative use of PPIs, the higher the osteoporotic fracture risk (P for trend < 0.001). The risk of osteoporotic fracture in the patients whose cumulative use of PPI was more than 1 year was higher than that of others (OR: 1.42, 95% CI: 1.32–1.52). Patients who regularly used PPI in the recent 1 year had a higher risk of osteoporotic fracture than exclusive H2RA users (OR: 1.37, 95% CI: 1.26–1.50).

Conclusions

The risk of osteoporotic fracture increased with the duration of PPI use, especially when PPI was used for ≥1 year and regularly in the recent 1 year.

Comparative analysis of the risk of osteoporotic fractures with proton pump inhibitor use and histamine-2 receptor antagonist therapy in elderly women: A nationwide population-based nested case-control study

The influence of proton pump inhibitors (PPIs) on the risk of osteoporotic fractures remains to be elucidated, especially in the Asian population. This study evaluated the risk of osteoporotic fractures in elderly female Korean PPI users compared to histamine-2 receptor antagonist (H2RA) users, as well as the relationship between fractures and the duration, dose, and pattern of use of PPI. We screened a nationwide cohort of elderly Korean women who underwent bone mineral density measurements during their 66-year-old life-transition medical examination between 2009 and 2014. Study subjects included 8903 cases diagnosed with new osteoporotic fractures and 44,515 matched controls (1:5 ratio based on cohort entry date, follow-up duration, and baseline osteoporosis status) without fractures. They were followed up until 2015. Information on the exposure to PPI or H2RA, occurrence of fracture, and covariates were obtained from the Korean National Health Insurance Service data. Covariate-adjusted odds ratio (aOR) and 95% confidence interval (CI) were estimated using conditional logistic regression analysis. PPI use was associated with an increased risk of osteoporotic fractures (aOR: 1.13, 95% CI: 1.07, 1.18) compared with H2RA-only use. Increasing duration of PPI use was positively associated with the risk of osteoporotic fracture [aOR (95% CI) of long-term PPI use (≥1 year): 1.3 (1.09, 1.56)]. Recent PPI use within the last year was associated with an increased risk of fracture (aOR: 1.31, 95% CI: 1.23, 1.38), whereas remote PPI use was not (aOR: 0.98, 95% CI: 0.92, 1.04). The risk of fracture did not increase with the increasing cumulative PPI dose. Compared with the use of H2RA alone, PPI use was associated with an increased risk of osteoporotic fractures in elderly Korean women, particularly among those who had used PPI within the last year or for more than one year.

Advanced Genetic Approaches in Discovery and Characterization of Genes Involved With Osteoporosis in Mouse and Human

Osteoporosis is a complex condition with contributions from, and interactions between, multiple genetic loci and environmental factors. This review summarizes key advances in the application of genetic approaches for the identification of osteoporosis susceptibility genes. Genome-wide linkage analysis (GWLA) is the classical approach for identification of genes that cause monogenic diseases; however, it has shown limited success for complex diseases like osteoporosis. In contrast, genome-wide association studies (GWAS) have successfully identified over 200 osteoporosis susceptibility loci with genome-wide significance, and have provided most of the candidate genes identified to date. Phenome-wide association studies (PheWAS) apply a phenotype-to-genotype approach which can be used to complement GWAS. PheWAS is capable of characterizing the association between osteoporosis and uncommon and rare genetic variants. Another alternative approach, whole genome sequencing (WGS), will enable the discovery of uncommon and rare genetic variants in osteoporosis. Meta-analysis with increasing statistical power can offer greater confidence in gene searching through the analysis of combined results across genetic studies. Recently, new approaches to gene discovery include animal phenotype based models such as the Collaborative Cross and ENU mutagenesis. Site-directed mutagenesis and genome editing tools such as CRISPR/Cas9, TALENs and ZNFs have been used in functional analysis of candidate genes in vitro and in vivo. These resources are revolutionizing the identification of osteoporosis susceptibility genes through the use of genetically defined inbred mouse libraries, which are screened for bone phenotypes that are then correlated with known genetic variation. Identification of osteoporosis-related susceptibility genes by genetic approaches enables further characterization of gene function in animal models, with the ultimate aim being the identification of novel therapeutic targets for osteoporosis.

Evaluation of WISP1 as a candidate gene for bone mineral density in the Old Order Amish

Wnt1-inducible signaling pathway protein-1 (WISP1) is a novel target of the Wnt pathway for modulating osteogenesis and improving bone strength. However, it is not clear if genetic variants in the WISP1 region are associated with bone mineral density (BMD) in human. The aim of this study is to investigate the role of genetic variation in WISP1 gene as a determinant of BMD in 1,510 Old Order Amish (OOA). We performed regional association analysis of 58 tag variants within 5 kb upstream and downstream to WISP1 with BMD and found 5 variants that were associated with BMD at multiple skeletal sites (P values from 2.89 × 10⁻⁶ to 1.62 × 10⁻²), with some significant associations even after adjustment for multiple comparisons. To replicate these results in an independent dataset, we performed a look-up of BMD associations with these variants in European ancestry subjects from the large GEFOS Consortium and observed the nominal associations of two of these variants with BMD (P values: 0.031 to 0.048). In conclusion, we have demonstrated that genetic variants surrounding WISP1 are associated with BMD at multiple skeletal sites in the OOA, thus influencing osteoporosis risk. These results support a role for the WISP1 gene on influencing variation in BMD.

Genetic association study identified a 20 kb regulatory element in WLS associated with osteoporosis and bone mineral density in Han Chinese

Previous studies have linked the WNT pathway and human skeleton formation; therefore, genes related to WNT might contribute to the onset and development of osteoporosis. In this study, we investigated the potential genetic association of WLS, which encodes an important mediator in the WNT pathway, with osteoporosis and its related quantitative traits in a sample of 6,620 individuals from Han Chinese population. A two-stage approach, with a discovery stage with 859 cases and 1,690 controls and a validation stage with 1,039 cases and 3,032 controls, was applied in the study. Forty SNPs were genotyped in the discovery stage. The intronic SNP rs2566752 was identified to be significantly associated with osteoporosis (OR_discovery = 0.78, P_discovery = 3.73 × 10⁻⁵; OR_validation = 0.80, P_validation = 1.96 × 10⁻⁵). Two SNPs surrounding rs2566752 (in addition to this SNP itself) were identified to be associated with bone mineral density. In addition, we have identified a 20 kb peak region of H3K27Ac histone mark enrichment between rs2772304 and rs2566752. Our study suggested that WLS is an important locus for osteoporosis and its related quantitative phenotypes in Han Chinese population. Additional sequencing-based studies are needed to investigate the genetic architecture of this regulatory region and its relationship with osteoporosis-related phenotypes.

Genetic influence on the association between bone mineral density and testosterone in Korean men

Low bone mineral density (BMD) leads to an increased risk of osteoporotic fracture. Total testosterone and free testosterone were positively associated with BMD, which was significantly influenced by the additive genetic effects.

INTRODUCTION

This cross-sectional study aimed to evaluate an association between testosterone and BMD and the influence of genetic factors on the association.

METHODS

Study subjects were 1070 Korean men including 144 pairs of monozygotic twins and their family members. Levels of serum total testosterone and sex hormone binding globulin (SHBG) were measured by chemiluminescence immunoassay. Calculated free testosterone (cFT) was then determined using Vermeulen's method. BMDs of the whole body and specific regions were measured using dual-energy X-ray absorptiometry.

RESULTS

Linear mixed regression analyses showed that total testosterone and cFT were positively associated with BMD at most regions, after considering intra-familial relationship and covariates including fat mass, lean mass, and SHBG. SHBG had an inverse association with BMD at the pelvis but not with the BMD at other regions after adjusting for all covariates and cFT. Co-twin control analysis in monozygotic twins found no association between pairwise difference of testosterone and pairwise difference of BMD. Bivariate variance component analysis showed that both total testosterone and cFT had a significant positive additive genetic correlation with BMD at rib, spine, and arm, whereas SHBG had no significant genetic correlation with BMD. Inverse environmental correlations were seen between total testosterone and BMDs at the lumbar spine and arm.

CONCLUSIONS

This Korean twin and family study showed that both total testosterone and free testosterone were positively associated with BMD and that genetic effects were significant on the association between testosterone and BMD.

Genetic analysis of bone quality traits and growth in a random mating broiler population

We report the genetic relationship between growth and bone quality traits in a random mating broiler control population. Traits studied were growth rates from week 0 to 4 [body weight gain (BWG) 0 to 4], from week 0 to 6 (BWG 0 to 6), and residual feed intake (RFI) from week 5 to 6 (RFI 5 to 6). Bone quality traits were obtained at 6 weeks of age. These traits were shank weight (SW), shank length (SL), shank diameter (SDIAM), tibia weight (TW), tibia length (TL), and tibia diameter (TDIAM). Likewise, tibia was used to obtain the tibia density (TDEN), tibia breaking strength (TBS), tibia mineral density (TMD), tibia mineral content (TMC), and tibia ash content (TAC). At the phenotypic level, growth traits were positively correlated with most of the bone quality traits except with TDEN and TAC which tended to show unfavorable associations (-0.04 to -0.31). Heritability of bone quality traits ranged from 0.08 to 0.54. The additive genetic associations of growth traits with weight, length, and diameter of shank and tibia were positive (0.37 to 0.80). A similar pattern was observed with TMD and TMC (0.06 to 0.65). In contrast, growth traits showed unfavorable genetic associations with TDEN, TBS, and TAC (-0.03 to -0.18). It was concluded that bone quality traits have an additive genetic background and they can be improved by means of genetic tools. It appears that selection for growth is negatively correlated with some traits involved in the integrity, health, and maturity of leg bones.

Gene-dietary fat interaction, bone mineral density and bone speed of sound in children: a twin study in China

SCOPE

Dietary fat correlates with bone mineral density (BMD). We tested the association between fat intake and BMD, and tested if fat intake modified the degree of genetic influence on BMD and bone speed of sound (SOS).

METHODS AND RESULTS

We included 622 twins aged 7-15 from South China. Data on anthropometry, dietary intake, BMD, and SOS were collected. Quantitative genetic analyses of structural equation models were fit using the Mx statistical package. The within-pair intraclass correlations for BMD in dizygotic twins were nearly half of that for monozygotic twins (intraclass correlations = 0.39 versus 0.70). The heritability of BMD and SOS were 71 and 79%. Phenotypic correlation between fat intake and SOS was significant (r = -0.19, p = 0.04). SOS was negatively correlated with fat intake in boys (r = -0.11, p = 0.05), but not in girls. Full Cholesky decomposition models showed SOS has a strong genetic correlation with fat intake (rA = -0.88, 95% confidence interval = -0.94, 0.01); the environmental correlation between fat intake and SOS was weak (rE = -0.04, 95% confidence interval = -0.20, 0.13). Fat intake modified the additive genetic effects on BMD.

CONCLUSION

Genetic factors explained 71 and 79% of individual variance in BMD and SOS, respectively. Low fat intake counteracts genetic predisposition to low BMD.

[Factors that influence bone mass of healthy children and adolescents measured by quantitative ultrasound at the hand phalanges: a systematic review]

Objective:

To analyze the main factors that influence bone mass in children and teenagers assessed by quantitative ultrasound (QUS) of the phalanges.

Data source:

A systematic literature review was performed according to the PRISMA method with searches in databases Pubmed/Medline, SciELO and Bireme for the period 2001-2012, in English and Portuguese languages, using the keywords: children, teenagers, adolescent, ultrasound finger phalanges, quantitative ultrasound of phalanges, phalangeal quantitative ultrasound.

Data synthesis:

21 articles were included. Girls had, in QUS, Amplitude Dependent Speed of Sound (AD-SoS) values higher than boys during pubertal development. The values of the parameters of QUS of the phalanges and dual-energy X-ray Absorptiometry (DXA) increased with the increase of the maturational stage. Anthropometric variables such as age, weight, height, body mass index (BMI), lean mass showed positive correlations with the values of QUS of the phalanges. Physical activity has also been shown to be positively associated with increased bone mass. Factors such as ethnicity, genetics, caloric intake and socioeconomic profile have not yet shown a conclusive relationship and need a larger number of studies.

Conclusions:

QUS of the phalanges is a method used to evaluate the progressive acquisition of bone mass during growth and maturation of individuals in school phase, by monitoring changes that occur with increasing age and pubertal stage. There were mainly positive influences variables of sex, maturity, height, weight and BMI, with similar data when compared to the gold standard method, the DXA.

Heritability of bone mineral density in a multivariate family-based study

There is evidence for a genetic contribution to bone mineral density (BMD×). Different loci affecting BMD have been identified by diverse linkage and genome-wide association studies. We studied the heritability of and the correlations among six densitometric phenotypes and four bone mass/fracture phenotypes. For this purpose, we used a family-based study of the genetics of osteoporosis, the Genetic Analysis of Osteoporosis Project. The primary aim of our study was to examine the roles of genetic and environmental factors in determining osteoporosis-related phenotypes. The project consisted of 11 extended families from Spain. All of them were selected through a proband with osteoporosis. BMD was measured using dual-energy X-ray absorptiometry. The proportion of variance of BMD attributable to significant covariates ranged from 25% (for femoral neck BMD) to 48% (for whole-body total BMD). The vast majority of the densitometric phenotypes had highly significant heritability, ranging from 0.252 (whole-body total BMD) to 0.537 (trochanteric BMD) after correcting for covariate effects. All of the densitometric phenotypes showed high and significant genetic correlations (from -0.772 to -1.000) with a low bone mass/osteopenia condition (Affected 3). Our findings provide additional evidence on the heritability of BMD and a strong genetic correlation between BMD and bone mass/fracture phenotypes in a Spanish population. Our results emphasize the importance of detecting genetic risk factors and the benefit of early diagnosis and especially therapeutic and preventive strategies.

A milk and cereal dietary pattern is associated with a reduced likelihood of having a low bone mineral density of the lumbar spine in Korean adolescents

The traditional rice-based Korean diet has been changing toward a Western-style diet. This change has been especially rapid among adolescents. The purpose of this study was to investigate the association between dietary patterns and bone health among Korean adolescents. This cross-sectional study was conducted on 196 adolescents aged 12 to 15 years. Information on the general characteristics of the subjects was obtained through a questionnaire, and dietary intake was assessed with 6-day food records. Bone mineral densities (BMDs) of the lumbar spine and femur were measured by dual-energy x-ray absorptiometry. Dietary patterns were derived from 24 food groups using factor analysis. Four distinct dietary patterns-traditional Korean, fast food, milk and cereal, and snacks-were identified and accounted for 28.4% of the total variance. After adjusting for sex, age, body mass index percentiles, weight loss attempts, pubertal status, and regular exercise, the adolescents in the highest tertile of the "milk and cereal" dietary pattern score had significantly a reduced likelihood of having low BMD compared with those in the lowest tertile of this diet at the lumbar spine (odds ratio, 0.36; 95% confidence interval, 0.14-0.93; P = .0461). The other dietary patterns were not associated with the BMD of Korean adolescents. These results indicate that the intake of milk and cereal is important for the bone health of Korean adolescents, whose diets are composed mainly of grains and vegetables.

Mitochondrial DNA copy number in peripheral blood is associated with femoral neck bone mineral density in postmenopausal women

OBJECTIVE

It has been suggested that mitochondrial dysfunction is related to aging and metabolic disorders. Yet there are few studies of the relationship between bone mineral density (BMD) and mitochondrial content in humans. We investigated the relationship between BMD and mitochondrial DNA (mtDNA) copy number in peripheral blood of postmenopausal women.

METHODS

The study included 146 postmenopausal women. Enrolled subjects were taking no medications and had no disorders that altered bone metabolism. We measured BMD using dual-energy x-ray absorptiometry and leukocyte mtDNA copy number using real-time polymerase chain reaction. Anthropometric evaluations and biochemical tests were performed.

RESULTS

Patients with osteopenia or osteoporosis had lower mtDNA copy numbers than normal subjects (p < 0.0001). Femoral neck BMD was negatively correlated with age (r = -0.01, p = 0.04) and with serum levels of adiponectin (r = -0.22, p = 0.01) and osteocalcin (r = -0.31, p = 0.0001). Serum levels of 25-OH vitamin D (r = 0.32, p < 0.0001) and mtDNA copy number (r = 0.36, p < 0.0001) were positively correlated with femoral neck BMD. Multiple regression analysis showed that mtDNA copy number (ß = 0.156, p < 0.001) was an independent factor associated with femoral neck BMD after adjustment for age, body mass index, waist circumference, waist-hip ratio, blood pressure, homeostatic model assessment of insulin resistance, high-sensitivity C-reactive protein, adiponectin, osteocalcin, homocysteine, lipid profiles, 25-OH vitamin D, and regular exercise. mtDNA copy number was not related to lumbar BMD.

CONCLUSION

Low mtDNA content in peripheral blood is related to decreased femoral neck BMD in postmenopausal women. Our findings suggest that mitochondrial dysfunction may be a potential pathophysiologic mechanism of osteoporosis in postmenopausal women.

Cortical bone health shows significant linkage to chromosomes 2p, 3p, and 17q in 10-year-old children

Genes play an important role in lifelong skeletal health. Genes that influence bone building during childhood have the potential to affect bone health not only throughout childhood but also into adulthood. Given that peak bone mass is a significant predictor of adult fracture risk, it is imperative that the genetic underpinnings of the normal pediatric skeleton are uncovered. In a sample of 600 10-year-old children from 144 families in the Fels Longitudinal Study, we examined radiographic cortical bone measures of the second metacarpal. Morphometic measurements included bone width, medial and lateral cortical thicknesses, and the calculated cortical index representing the amount of cortex relative to bone width. We then conducted genome-wide linkage analysis on these traits in 440 genotyped individuals using the SOLAR analytic platform. Significant quantitative trait loci (QTL) were identified for bone traits on three separate chromosomes. A QTL for medial cortical thickness was localized to chromosome 2p25.2. A QTL for lateral cortical thickness was localized to chromosomal region 3p26.1-3p25.3. Finally, a QTL detected for cortical index was localized to the 17q21.2 chromosomal region. Each region contains plausible candidate genes for pediatric skeletal health, some of which confirm findings from studies of adulthood bone, and for others represent novel candidate genes for skeletal health.