Muscle-origin creatinine-cystatin C ratio is an osteoporosis marker in individuals with normal renal function: evidence from observational and Mendelian randomization analysis.

Background: Creatinine-cystatin C ratio (CCR) has been demonstrated as an objective marker of sarcopenia in clinical conditions but has not been evaluated as an osteoporosis marker in individuals with normal renal function. Methods: We selected 271,831 participants with normal renal function from UK Biobank cohort. Multivariable linear/logistic regression and Cox proportional hazards model were used to investigate the phenotypic relationship between CCR and osteoporosis in total subjects and gender-stratified subjects. Based on the genome-wide association study (GWAS) data, linkage disequilibrium regression (LDSC) and Mendelian randomization (MR) analysis were performed to reveal the shared genetic correlations and infer the causal effects, respectively. Results: Amongst total subjects and gender-stratified subjects, serum CCR was positively associated with eBMD after adjusting for potential risk factors (all P<0.05). The multivariable logistic regression model showed that the decrease in CCR was associated with a higher risk of osteoporosis/fracture in all models (all P<0.05). In the multivariable Cox regression analysis with adjustment for potential confounders, reduced CCR is associated with the incidence of osteoporosis and fracture in both total subjects and gender-stratified subjects (all P<0.05). A significant non-linear dose-response was observed between CCR and osteoporosis/fracture risk (P non-linearity < 0.05). LDSC found no significant shared genetic effects by them, but PLACO identified 42 pleiotropic SNPs shared by CCR and fracture (P<5×10-8). MR analyses indicated the causal effect from CCR to osteoporosis/fracture. Conclusions: Reduced CCR predicted increased risks of osteoporosis/fracture, and significant causal effects support their associations. These findings indicated that the muscle-origin serum CCR was a potential biomarker to assess the risks of osteoporosis and fracture.

Establishment of reference intervals for bone turnover markers in healthy Chinese older adults.

BACKGROUND: Reference ranges for bone turnover markers (BTMs) are still lacking in the healthy Chinese population. AIM: To establish reference intervals for BTMs and to investigate the correlations between BTMs and bone mineral density (BMD) in Chinese older adults. SUBJECTS AND METHODS: A community-based cross-sectional study was conducted among 2511 Chinese subjects aged over 50 yrs residing in Zhenjiang, Southeast China. Reference intervals for BTMs (i.e. procollagen type I N-terminal propeptide, P1NP; ß cross-linked C-terminal telopeptide of type I collagen, ß-CTX) were calculated as the central 95% range of all measurements in Chinese older adults. RESULTS: The reference intervals of P1NP, ß-CTX and P1NP/ß-CTX were 15.8-119.9 ng/mL, 0.041-0.675 ng/mL and 49.9-1261.5 for females and 13.6-111.4 ng/mL, 0.038-0.627 ng/mL and 41.0-1269.1 for males, respectively. In the multiple linear regression analysis, only ß-CTX was negatively associated with BMD after adjusting for age and body mass index (BMI) in both sex-stratified groups (all p < .05). CONCLUSION: This study established age- and sex-specific reference intervals for BTMs in a large sample of healthy Chinese participants ≥ 50 and < 80 years of age and explored the correlations between BTMs and BMD, which provides an effective reference for the assessment of bone turnover in the clinical practice of osteoporosis.

A novel long non-coding RNA, lnc-RNU12, influences the T-cell cycle via c-JUN and CCNL2 in rheumatoid arthritis.

OBJECTIVES: Long non-coding RNAs (lncRNAs) play important roles in RA pathogenesis. However, specific lncRNAs that regulate gene expression in RA pathogenesis are poorly known. This study was undertaken to characterize a novel lncRNA (lnc-RNU12) that has a lower-than-normal expression level in RA patients. METHODS: We performed initial genome-wide lncRNA microarray screening in peripheral blood mononuclear cells from 28 RA cases and 18 controls. Multiple methods were used to validate the detected associations between lncRNAs and RA. Furthermore, we identified the source and characteristics of the highlighted lncRNAs, detected the target genes, and determined the functional effect on immune cells through lncRNA knock-down in Jurkat T cell lines. RESULTS: lnc-RNU12 was downregulated in peripheral blood mononuclear cells and T cell subtypes of RA patients and was genetically associated with RA risk. lnc-RNU12 mediates the effect of microbiome alterations on RA risk. Activation of T cells caused low expression of lnc-RNU12. Knock-down of lnc-RNU12 in Jurkat T cells caused cell cycle S-phase arrest and altered the expression of protein-coding genes related to the cell cycle and apoptosis (e.g. c-JUN, CCNL2, CDK6, MYC, RNF40, PKM, VPS35, DNAJB6 and FLCN). Finally, c-JUN and CCNL2 were identified as target genes of lnc-RNU12 at the mRNA and protein expression levels. RNA-binding protein immunoprecipitation assays verified the interaction between lnc-RNU12 and the two proteins (c-Jun and cyclin L2) in Jurkat cells. CONCLUSIONS: Our study suggested that lnc-RNU12 was involved in the pathogenesis of RA by influencing the T cell cycle by targeting c-JUN and CCNL2.

The immune factors have complex causal regulation effects on bone mineral density.

Recent evidence has gradually recognized that the immune and skeletal systems are two closely correlated systems, but the specific immune factors on bone mineral density (BMD) are largely unknown. Based on the summary-level data of genome-wide association studies (GWASs), we performed a series of analyses including two-sample Mendelian randomization (MR) analysis to test potential causal links between 731 immune traits [including median fluorescence intensities (MFIs), absolute cell (AC) counts, relative cell (RC) counts, and morphological parameters (MP)] and BMD. After false discovery rate (FDR) correction, 9 MFI-BMD, 16 AC-BMD, 22 RC-BMD, and 5 MP-BMD pairs reached the level of significance (FDR-adjusted p< 0.05). For MFI traits, the T- and B-cell panels had the largest number of significant immune trait pairs than other panels. CD40, as a molecule expressed by four subsets of monocytes, was highlighted due to its consistently positive correlation with BMD at four sites. For both AC and RC traits, immune traits from the T-cell panel were also highlighted, with CD39-positive T-cell subsets being the most frequently observed feature. For MP traits, the most significant association immune trait with BMD was SSC-A on CD14+ monocyte. Sensitivity analyses suggested that the identified immune factors were robust to pleiotropy. Multivariable MR analysis confirmed the independent causal effect of several immune traits on BMD. Mediation analyses showed that CD40 on monocytes could mediate multiple immune traits, especially the suggestive associations of CD27 on several memory B cells with BMD mediated by CD40 on CD14+ CD16- monocyte. Our study represents the first comprehensive evaluation of the causal effects of immune traits on the risk of osteoporosis. The findings highlighted the complex and important role of immune-derived factors in the pathogenesis of osteoporosis.

Systematic Evaluation of Rheumatoid Arthritis Risk by Integrating Lifestyle Factors and Genetic Risk Scores.

Background: Effective identification of high-risk rheumatoid arthritis (RA) individuals is still a challenge. Whether the combined effects of multiple previously reported genetic loci together with lifestyle factors can improve the prediction of RA risk remains unclear. Methods: Based on previously reported results and a large-scale Biobank dataset, we constructed a polygenic risk score (PRS) for RA to evaluate the combined effects of the previously identified genetic loci in both case-control and prospective cohorts. We then evaluated the relationships between several lifestyles and RA risk and determined healthy lifestyles. Then, the joint effects of healthy lifestyles and genetic risk on RA risk were evaluated. Results: We found a positive association between PRS and RA risk (OR = 1.407, 95% confidence interval (CI) = 1.354~1.463; HR = 1.316, 95% CI = 1.257~1.377). Compared with the low genetic risk group, the group with intermediate or high genetic risk had a higher risk (OR = 1.347, 95% CI = 1.213~1.496; HR = 1.246, 95% CI = 1.108~1.400) (OR = 2.169, 95% CI = 1.946~2.417; HR = 1.762, 95% CI = 1.557~1.995). After adjusting for covariates, we found protective effects of three lifestyles (no current smoking, regular physical activity, and moderate body mass index) on RA risk and defined them as healthy lifestyles. Compared with the individuals with low genetic risks and favorable lifestyles, those with high genetic risks and unfavorable lifestyles had as high as OR of 4.637 (95%CI = 3.767~5.708) and HR of 3.532 (95%CI = 2.799~4.458). Conclusions: In conclusion, the integration of PRS and lifestyles can improve the prediction of RA risk. High RA risk can be alleviated by adopting healthy lifestyles but aggravated by adopting unfavorable lifestyles.

Epigenetically regulated co-expression network of genes significant for rheumatoid arthritis.

Aim: To identify epigenetically regulated network of genes in peripheral blood mononuclear cells significant for rheumatoid arthritis (RA). Methods: Differentially expressed genes (DEGs) and their associated differentially expressed miRNAs and differentially methylated positions (DMPs) were identified. Causal inference test (CIT) identified the causal regulation chains. The analyses, for example, weighted gene co-expression network (WGCNA), protein-protein interaction and functional enrichment, evaluated interaction patterns among the DEGs and the associated epigenetic factors. Results: A total of 181 DEGs were identified. The DEGs were significantly regulated by DMPs and/or differentially expressed miRNAs. Causal inference test analyses identified 18 causal chains of DMP-DEG-RA and 16 intermediate DEGs enriched in 'protein kinase inhibitor activity'. BTN2A1 was co-expressed with other 9 intermediate genes and 11 known RA-associated genes and played a pivotal role in the co-expression network. Conclusion: Epigenetically regulated network of genes in peripheral blood mononuclear cells (PBMC) contributed to RA. The causal DMPs and key intermediate genes may serve as potential biomarkers for RA.

Exosome: An Emerging Source of Biomarkers for Human Diseases.

Exosomes are 30-120nm long endocytic membrane-derived vesicles, which are secreted by various types of cells and stably present in body fluids, such as plasma, urine, saliva and breast milk. Exosomes participate in intercellular communication. Recently accumulative studies have suggested that exosomes may serve as novel biomarkers for disease diagnosis and prognosis. Herein, we reviewed the biological features of exosomes, technologies for exosome isolation and identification, as well as progress in exosomal biomarker identification, highlighting the relevance of exosome to human diseases and significance and great potential in translational medicine.

Abl interactor 1: A novel biomarker for osteoporosis in Chinese elderly men.

Low bone mineral density (BMD) is a high-risk factor of osteoporosis (OP) and osteoporotic fracture (OF). Peripheral blood monocytes (PBM) can give birth to osteoclasts to resorb bone. Herein, we attempted to identify OP susceptible proteins in human PBM and characterize their functions in bone. Employing the label-free quantitative proteomics methodology (Easy-nLC1000 and Q-exactive) and traditional Western Blotting (WB), we discovered and validated that a key protein, i.e. Abl Interactor 1(ABI1), was significantly down-regulated in PBM in Chinese elderly men with extremely low vs. high BMD (n = 18, p < .05), as well as in OF patients vs. non-fractured (NF) subjects (n = 36, p < .05). The above down-regulation tendency was also observed in Chinese elderly women (n = 51, P < .05). For translational purpose, plasma ABI1 protein was assessed by ELISA in Chinese elderly men, which was found significantly down-regulated in OF (n = 20) vs. NF (n = 64) subjects (Mean: 0.41 vs. 1.03 ng/ml, FC = 0.39, p = .039), as well as in low (n = 32) vs. high (n = 32) BMD subjects (Mean: 0.5 vs. 1.57 ng/ml, FC = 0.32,p = .0012). ROC analyses in another independent study sample (n = 75) showed that the plasma ABI1 protein has superior performance in discriminating osteopenia and healthy subjects (AUC = 0.755, 95% CI: 0.632-0.877, p = .001). Follow-up cellular functional studies revealed that ABI1 protein significantly promoted osteoblast growth (optimal concentration 2.0 ng/ml), osteoblastic gene expression (OPN, ALP, COL1A1, p < .05) and osteoblast differentiation.ABI1 protein also significantly attenuated monocyte trans-endothelial migration and osteoclast differentiation and activity. In conclusion, ABI1 is a novel protein biomarker for OP in Chinese elderly. ABI1 protein, via promoting osteoblast growth, differentiation and activity, and attenuating monocyte trans-endothelial migration and osteoclast differentiation, influences BMD variation and fracture risk in humans. SIGNIFICANCE: Previous plentiful studies indicated that protein ABI1 played an essential role in the progression of several malignancies, including hepatoma, colon cancer and epithelial ovarian cancer. However, there was relatively limited understandings regarding its molecular and cellular functions relevant to bone phenotypes. Employing the label-free quantitative proteomics methodology (Easy-nLC1000 and Q-exactive) and traditional Western Blotting (WB), we discovered and validated that ABI1 was significantly down-regulated in PBM in Chinese elderly men with extremely low BMD as well as in OF patients. The down-regulation trend was consistent in plasma samples in Chinese elderly men. Follow-up cellular functional studies revealed that, on the one hand, ABI1 protein significantly promoted osteoblast growth, osteoblastic gene expression and osteoblast differentiation; on the other hand, it also significantly attenuated monocyte trans-endothelial migration and osteoclast differentiation and activity. It suggested that ABI1 is a promising biomarker with translational value.

Integrative Analysis Confirmed the Association between Osteoprotegerin and Osteoporosis.

Objective This study aimed to verify the association between osteoprotegerin gene (OPG) and its variants with osteoporosis (OP) by performing integrative analysis.Methods We used the KGG software to perform gene-based association analysis, which integrated all publicly available single-nucleotide polymorphism (SNP)-based P values and obtained an overall P value for the OPG. The significant SNPs were screened for expression quantitative trait loci (eQTLs). Meta-analysis was used to combine the associations between the variants of OPG and bone mineral density (BMD) reported in the literatures. Then we performed dual-luciferase reporter gene systems for the functional verification of the variants of OPG in vitro.Results In the gene-based association analysis, the over all P value of OPG was 6.24×10 -13for BMD at femoral neck (FN) and 7.37×10 -17 for BMD at lumbar spine (LS), indicating the importance of OPG for OP. The publicly available eQTL database identified 5 eQTLs which exert cis-regulation effects on OPG at FN and LS. Literature searching found that rs2073617 (known as T950C) was the hot spot SNP. There were 13 relevant studies on rs2073617 besides the GEFOS-2 study identified from the PubMed. Significant differences among TT, TC and CC genotypes at FN (P= 0.047) and LS (P= 0.025) were shown by meta-analysis, demonstrating the associations between T950C polymorphism and BMD. Luciferase gene expression was significantly higher at the presence of allele C than allele T in the 293T cells (t=-9.47, P<0.01). Conclusion The integrative analysis further confirmed the importance of OPG in OP and the correlation of T950C polymorphism with BMD of OP. The strategy can be used as a reference for functional interpretation of other disease-related genes.

SAMD9 is a (epi-) genetically regulated anti-inflammatory factor activated in RA patients.

To identify PBMC-expressed genes significant for RA, and to ascertain their upstream regulatory factors, as well as downstream functional effects relevant to RA pathogenesis. We performed peripheral blood mononuclear cells (PBMCs) transcriptome-wide mRNA expression profiling in a case-control discovery sample. Differentially expressed genes (DEGs) were identified and validated in PBMCs in independent samples. We also generated genome-wide SNP genotyping data, and collected miRNA expression data and DNA methylation data from PBMCs of the discovery sample. Pearson correlation analyses were conducted to identify miRNAs/DNA methylations influencing DEG expression. Association analyses were conducted to identify expression-regulating SNPs. The key DEG, SAMD9, which was reported to function as a tumor suppressor gene, was assessed for its effects on T cell proliferation, apoptosis, and inflammatory cytokine expression. A total of 181 DEGs (Fold Change ≥ 2.0, Bonferroni adjusted p ≤ 0.05) were discovered in PBMCs. Four DEGs (SAMD9, CKLF, PARP9, and GUSB), upregulated with RA, were validated independently in PBMCs. Specifically, SAMD9 mRNA expression level was significantly upregulated in PHA-activated Jurkat T cells in vitro, and correlated with 8 miRNAs and associated with 22 SNPs in PBMCs in vivo. Knockdown of SAMD9 could transiently promote Jurkat T cell proliferation within 48 h and significantly induce TNF-α and IL-8 expression in T cells. SAMD9 expression is (epi-) genetically regulated, and significantly upregulated in PBMCs in RA patients and in activated T cells in vitro. SAMD9 might serve as a T cell activation marker but act as an anti-inflammatory factor.

Rheumatoid arthritis-associated DNA methylation sites in peripheral blood mononuclear cells.

OBJECTIVES: To identify novel DNA methylation sites significant for rheumatoid arthritis (RA) and comprehensively understand their underlying pathological mechanism. METHODS: We performed (1) genome-wide DNA methylation and mRNA expression profiling in peripheral blood mononuclear cells from RA patients and health controls; (2) correlation analysis and causal inference tests for DNA methylation and mRNA expression data; (3) differential methylation genes regulatory network construction; (4) validation tests of 10 differential methylation positions (DMPs) of interest and corresponding gene expressions; (5) correlation between PARP9 methylation and its mRNA expression level in Jurkat cells and T cells from patients with RA; (6) testing the pathological functions of PARP9 in Jurkat cells. RESULTS: A total of 1046 DNA methylation positions were associated with RA. The identified DMPs have regulatory effects on mRNA expressions. Causal inference tests identified six DNA methylation-mRNA-RA regulatory chains (eg, cg00959259-PARP9-RA). The identified DMPs and genes formed an interferon-inducible gene interaction network (eg, MX1, IFI44L, DTX3L and PARP9). Key DMPs and corresponding genes were validated their differences in additional samples. Methylation of PARP9 was correlated with mRNA level in Jurkat cells and T lymphocytes isolated from patients with RA. The PARP9 gene exerted significant effects on Jurkat cells (eg, cell cycle, cell proliferation, cell activation and expression of inflammatory factor IL-2). CONCLUSIONS: This multistage study identified an interferon-inducible gene interaction network associated with RA and highlighted the importance of PARP9 gene in RA pathogenesis. The results enhanced our understanding of the important role of DNA methylation in pathology of RA.

Identification and evaluation of lncRNA and mRNA integrative modules in human peripheral blood mononuclear cells.

AIM: To identify sets of functionally related long noncoding RNAs (lncRNAs) and mRNAs and to evaluate the importance of lncRNAs in an lncRNA-mRNA network. METHODS: We carried out weighted gene co-expression network analysis and enrichment analyses to identify functional modules of co-expressed lncRNAs and mRNAs in human peripheral blood mononuclear cells of 43 females. RESULTS: We identified seven modules and found hub lncRNAs in each module. Four of the seven modules had significant gene ontology enrichments. Some of the hub lncRNAs (e.g., SSX8, UCA1, HOXA-AS2, STARD4-AS1 and PCBP1-AS1) have known functions related with diseases such as cancers. CONCLUSION: We identified seven biologically important lncRNA and mRNA integrative modules in females and showed that lncRNAs might play important roles in lncRNA-mRNA co-expression modules.

Mass spectrometry based proteomics profiling of human monocytes.

Human monocyte is an important cell type which is involved in various complex human diseases. To better understand the biology of human monocytes and facilitate further studies, we developed the first comprehensive proteome knowledge base specifically for human monocytes by integrating both in vivo and in vitro datasets. The top 2000 expressed genes from in vitro datasets and 779 genes from in vivo experiments were integrated into this study. Altogether, a total of 2237 unique monocyte-expressed genes were cataloged. Biological functions of these monocyte-expressed genes were annotated and classified via Gene Ontology (GO) analysis. Furthermore, by extracting the overlapped genes from in vivo and in vitro datasets, a core gene list including 541 unique genes was generated. Based on the core gene list, further gene-disease associations, pathway and network analyses were performed. Data analyses based on multiple bioinformatics tools produced a large body of biologically meaningful information, and revealed a number of genes such as SAMHD1, G6PD, GPD2 and ENO1, which have been reported to be related to immune response, blood biology, bone remodeling, and cancer respectively. As a unique resource, this study can serve as a reference map for future in-depth research on monocytes biology and monocyte-involved human diseases.

Multistage genome-wide association meta-analyses identified two new loci for bone mineral density.

Aiming to identify novel genetic variants and to confirm previously identified genetic variants associated with bone mineral density (BMD), we conducted a three-stage genome-wide association (GWA) meta-analysis in 27 061 study subjects. Stage 1 meta-analyzed seven GWA samples and 11 140 subjects for BMDs at the lumbar spine, hip and femoral neck, followed by a Stage 2 in silico replication of 33 SNPs in 9258 subjects, and by a Stage 3 de novo validation of three SNPs in 6663 subjects. Combining evidence from all the stages, we have identified two novel loci that have not been reported previously at the genome-wide significance (GWS; 5.0 × 10(-8)) level: 14q24.2 (rs227425, P-value 3.98 × 10(-13), SMOC1) in the combined sample of males and females and 21q22.13 (rs170183, P-value 4.15 × 10(-9), CLDN14) in the female-specific sample. The two newly identified SNPs were also significant in the GEnetic Factors for OSteoporosis consortium (GEFOS, n = 32 960) summary results. We have also independently confirmed 13 previously reported loci at the GWS level: 1p36.12 (ZBTB40), 1p31.3 (GPR177), 4p16.3 (FGFRL1), 4q22.1 (MEPE), 5q14.3 (MEF2C), 6q25.1 (C6orf97, ESR1), 7q21.3 (FLJ42280, SHFM1), 7q31.31 (FAM3C, WNT16), 8q24.12 (TNFRSF11B), 11p15.3 (SOX6), 11q13.4 (LRP5), 13q14.11 (AKAP11) and 16q24 (FOXL1). Gene expression analysis in osteogenic cells implied potential functional association of the two candidate genes (SMOC1 and CLDN14) in bone metabolism. Our findings independently confirm previously identified biological pathways underlying bone metabolism and contribute to the discovery of novel pathways, thus providing valuable insights into the intervention and treatment of osteoporosis.

The human calcium-sensing receptor and interleukin-6 genes are associated with bone mineral density in Chinese.

Calcium sensing receptor (CASR) is a central factor involved in calcium metabolism. Interleukin-6 (IL-6) is a pleiotropic cytokine that plays an important role in osteoclast differentiation. Thus, both CASR and IL-6 are important in bone and mineral metabolism and are prominent candidate genes for osteoporosis. The study aimed to test association and/or linkage between the CASR and IL-6 genes with bone mineral density (BMD) variation in a Chinese population. A cytosine-adenine (CA)n repeat polymorphism in the CASR gene and the IL-6 gene was genotyped, respectively, in 1,263 subjects from 402 Chinese nuclear families. Employing tests implemented in the program QTDT (quantitative transmission disequilibrium tests), a significant total association of the CASR (CA)12 allele (P = 0.006) and (CA)18 allele (P = 0.02) with BMD at the femoral neck was found. For the IL-6 gene, significant within-family associations were found between the (CA)14 allele and BMD at the total hip (P = 0.021), the femoral neck (P = 0.041), and the intertrochanteric region (P = 0.029). A significant linkage was also observed between IL-6 CA repeat polymorphism and BMD at the spine (P = 0.001). The results suggest that the CASR gene and the IL-6 gene may have effects on BMD variation in Chinese.

Receiver-operating characteristic analyses of body mass index, waist circumference and waist-to-hip ratio for obesity: Screening in young adults in central south of China.

BACKGROUND & AIMS: Recent data suggest that current obesity diagnostic criterion based on body mass index (BMI) above 30 in Caucasians may not be appropriate for Asian populations. Our aim was to identify the usefulness of BMI, waist circumference (WC) and waist-to-hip ratio (WHR) in screening for obesity in an Asian population. METHODS: A cross-sectional sample of 1109 males and 879 females aged 20-45-yr were recruited. Height, weight, WC, hip circumference and percentage body fat (PBF) were measured in all subjects. Then receiver-operating characteristic analyses were used to evaluate the performances of the three anthropometric indices. RESULTS: BMI, WC and WHR showed strong positive correlation with PBF (r=0.47-0.75) in both males and females within both age groups. True-positive rates ranged from 82.4% to 94.1% and 68.8% to 86.3% in males and females, respectively. True-negative rates ranged from 64.1% to 84.7% and from 56.9% to 79.0%, respectively. The areas under the curves (AUCs) for WC and BMI were high (0.76-0.92) in both sexes and divided age groups (20-30-yr and 31-45-yr), and those for WHR were a little lower (0.74-0.88). CONCLUSIONS: BMI and WC are two important predictors for obesity in Chinese, and WHR is an alternative.

Potential effect of inter-genic action on peak bone mass (PBM) in Chinese females.

Peak bone mass (PBM) is a complex trait, determined by both genetic and environmental factors and also their interactions. Vitamin D receptor (VDR) estrogen receptor alpha (ERalpha), interleukin 6 (IL6), parathyroid hormone (PTH), collagen type I alpha 2 (COL1A2), bone Gla protein (BGP), alpha2-HS glycoprotein (AHSG) are among the important candidate genes of bone metabolism. The study aims to detect significant effect of potential inter-genic action underlying PBM in Chinese females. 361 unrelated healthy premenopausal Chinese females (aged 20 -44 years) with Han ethnicity were recruited from the Shanghai city in China. Bone mineral density (BMD) at the hip and the lumbar spine (L1-4) was measured using a Hologic QDR 2000 + dual-energy X-ray absorptiometry (DXA) scanner. Eight polymorphisms among the seven genes were genotyped, i. e. Apa I in VDR, Pvu II and Xba I in ERa (ERX and ERP, respectively), BsrB I in IL6, BstB I in PTH, Msp I in COL1A2, Hind III in BGP, and Sac I in AHSG, using PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) methods. Two-way analysis of variance (ANOVA) showed significant effects of IL6 x ERP interaction on PBM at the total hip (P = 0.019), intertrochanter (P = 0.016), and femoral neck (P =0. 019). The BMD difference between GGPp carriers and GGpp subjects (at these two loci) amounted to 18.0%, 19.5%, and 14.8% at the hip,intertrochanter,and femoral neck,respectively. The potential interaction effect of AHSG x IL6 was observed on femoral neck PBM (P = 0.046). GGSS individuals (at these two loci) had, on average, 18.8% higher femoral neck BMD than those subjects with GGSs genotype. The population-level statistical analysis indicates that IL6 x ERP and AHSG x IL6 have significant inter-genic effect on the genetic determination of PBM in Chinese females.

Estrogen receptor alpha gene relationship with peak bone mass and body mass index in Chinese nuclear families.

Estrogen receptor alpha (ER-alpha) plays an important role in mediating estrogen signaling. Studies in Caucasian populations have shown that it is involved in endocrine-related diseases such as osteoporosis and obesity. In the present study, we first used a quantitative transmission disequilibrium test (QTDT) to examine the relationship between this gene and both the osteoporosis-related phenotype bone mineral density (BMD), and the obesity-related phenotype body mass index (BMI), in 384 Chinese nuclear families. We genotyped a dinucleotide repeat marker (TA)n, and a long-range haplotype was reconstructed using this marker and two other restriction fragment length polymorphism (RFLP) markers at PvuII and XbaI loci. Although we found significant total association [allele (TA)21 with hip BMD (P=0.001), and haplotype Px(TA)21 with spine (P=0.0007) and hip (P=0.0006) BMD], the more reliable within-family associations were not significant between these phenotype pairs. No linkage signal was obtained for either spine BMD or hip BMD. We found no association or linkage between any of the three studied polymorphisms and the long-range haplotypes of the ER-alpha gene and BMI. Our study does not support an association of the ER-alpha gene with BMD and BMI in the Chinese population.

Association and linkage analyses of interleukin-6 gene 634C/G polymorphism and bone phenotypes in Chinese.

In this study, we tested the interleukin-6 (IL-6) gene as an important candidate gene for its linkage and association with the variation of bone phenotypes (bone mineral density [BMD] and bone size) in young Chinese female subjects. We genotyped the IL-6 gene at the -634C/G restriction fragment length polymorphism (RFLP) site (ID, RS1800796) in 1263 individuals from 402 Chinese nuclear families, composed of both parents and at least one healthy daughter (mean age +/- SD, 31.4 +/- 5.8 years). Using the daughters' bone phenotypes, we tested total-family association, within-family association (via transmission disequilibrium test, [TDT]), and linkage, between the -634C/G marker and bone phenotypes at the spine and the hip. No significant association or linkage was found for bone size and BMD, although a trend was observed for linkage between the IL-6 gene -634C/G marker and L1-4 spinal BMD (adjusted for age, weight, and height). Our results, together with the findings from other studies, indicate that the IL-6 gene, although important for postmenopausal bone loss, may have a limited impact on peak bone mass variation in a Chinese population.

Bone mineral density and five prominent candidate genes in Chinese men: associations, interaction effects and their implications.

OBJECTIVES: Osteoporosis constitutes a serious health problem in old people. Bone mineral density (BMD) is determined by multiple genetic and environmental factors. The genetic control of BMD and osteoporosis is better understood in women, but much less in men. The present study evaluated the relationship of COL1A2, BGP, IL-6, AHSG and PTH genes defined by MspI, HindIII, BsrBI, SacI and BstBI restriction enzymes, respectively, with BMD in Chinese males. METHODS: A total of 258 unrelated healthy Chinese men aged 50-80 years were recruited. BMD at spine (L1-4) and femoral neck were measured by a Hologic 2000+ densitometer and adjusted by significant covariates of age, height and weight. All the subjects were genotyped at the upper five polymorphic sites by PCR-RFLP procedure. RESULTS: We revealed significant association of the AHSG gene with the spine BMD (P = 0.006), even after adjusting for multiple testing in our study. Carriers of 1*1 and 2*2 genotypes of AHSG gene had, respectively, approximately 5.1 and 8.1% higher spine BMD than those of 1*2 genotype. For the other four genes, no evidence of association was found (P > 0.10). No significant evidence of gene-by-gene interaction was found by two-way factorial ANOVA on the BMD variation. CONCLUSIONS: The results suggest that the AHSG gene is associated with the spine BMD in Chinese men. The present study represents the first effort to simultaneously investigate the effects of single gene locus as well as gene-by-gene interactions of multiple genes on BMD variation in Chinese men.