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1.  Identification of novel risk genes associated with type 1 diabetes mellitus using a genome-wide gene-based association analysis 
Type 1 diabetes mellitus is a serious disorder characterized by destruction of pancreatic β-cells, culminating in absolute insulin deficiency. Genetic factors contribute to the susceptibility of type 1 diabetes mellitus. The aim of the present study was to identify more susceptibility genes of type 1 diabetes mellitus.
Materials and Methods
We carried out an initial gene-based genome-wide association study in a total of 4,075 type 1 diabetes mellitus cases and 2,604 controls by using the Gene-based Association Test using Extended Simes procedure. Furthermore, we carried out replication studies, differential expression analysis and functional annotation clustering analysis to support the significance of the identified susceptibility genes.
We identified 452 genes associated with type 1 diabetes mellitus, even after adapting the genome-wide threshold for significance (P < 9.05E-04). Among these genes, 171 were newly identified for type 1 diabetes mellitus, which were ignored in single-nucleotide polymorphism-based association analysis and were not previously reported. We found that 53 genes have supportive evidence from replication studies and/or differential expression studies. In particular, seven genes including four non-human leukocyte antigen (HLA) genes (RASIP1, STRN4, BCAR1 and MYL2) are replicated in at least one independent population and also differentially expressed in peripheral blood mononuclear cells or monocytes. Furthermore, the associated genes tend to enrich in immune-related pathways or Gene Ontology project terms.
The present results suggest the high power of gene-based association analysis in detecting disease-susceptibility genes. Our findings provide more insights into the genetic basis of type 1 diabetes mellitus.
PMCID: PMC4234227  PMID: 25422764
Genome-wide Gene-Based Association Study; Knowledge-based mining system for Genome-wide Genetic studies; Type 1 diabetes mellitus
2.  An Integrative Study Ascertained SOD2 as a Susceptibility Gene for Osteoporosis in Chinese 
Journal of Bone and Mineral Research  2011;26(11):2695-2701.
Osteoporosis (OP) is characterized by low bone mineral density (BMD) and has strong genetic determination. However, specific genetic variants influencing BMD and contributing to pathogenesis of osteoporosis are largely uncharacterized. Current genetic studies in bone filed, which aimed at identification of OP risk genes, are mostly focused on DNA, RNA, or protein level individually, lacking integrative evidences from the three levels of genetic information flow to confidently ascertain the significance of genes for osteoporosis. Our previous proteomics study discovered that superoxide dismutase 2 (SOD2) in circulating monocytes (CMCs, i.e., potential osteoclast precursors) was significantly up-regulated at protein level in vivo in Chinese with low vs. high hip BMD. Herein, at mRNA level, we found that SOD2 gene expression was also up-regulated in CMC (p < 0.05) in Chinese with low vs. high hip BMD. At DNA level, in 1,627 unrelated Chinese subjects, we identified eight SNPs at SOD2 gene locus that were suggestively associated with hip BMD (peak signal at rs11968525, p = 0.048). Among the eight SNPs, three SNPs (rs7754103, rs7754295, and rs2053949) were associated with SOD2 mRNA expression level (p < 0.05), suggesting that they are expression quantitative trait locus (eQTL) regulating SOD2 gene expression. In conclusion, the present integrative evidences from DNA, RNA, and protein levels supported SOD2 as a susceptibility gene for osteoporosis.
PMCID: PMC3375319  PMID: 21773993
Osteoporosis; SOD2; eQTL; BMD
3.  ANKRD7 and CYTL1 are novel risk genes for alcohol drinking behavior 
Chinese medical journal  2012;125(6):1127-1134.
Alcohol dependence (AD) is a complex disorder characterized by impaired control over drinking. It is determined by both genetic and environmental factors. The recent approach of genome-wide association study (GWAS) is a powerful tool for identifying complex disease-associated susceptibility alleles, however, a few GWASs have been conducted for AD, and their results are largely inconsistent. The present study aimed to screen the loci associated with alcohol-related phenotypes using GWAS technology.
A genome-wide association study with the behavior of regular alcohol drinking and alcohol consumption was performed to identify susceptibility genes associated with AD, using the Affymetrix 500K SNP array in an initial sample consisting of 904 unrelated Caucasian subjects. Then, the initial results in GWAS were replicated in three independent samples: 1972 Caucasians in 593 nuclear families, 761 unrelated Caucasian subjects, and 2955 unrelated Chinese Hans.
Several genes were associated with the alcohol-related phenotypes at the genome-wide significance level, with the ankyrin repeat domain 7 gene (ANKRD7) showing the strongest statistical evidence for regular alcohol drinking and suggestive statistical evidence for alcohol consumption. In addition, certain haplotypes within the ANKRD7 and cytokine-like1 (CYTL1) genes were significantly associated with regular drinking behavior, such as one ANKRD7 block composed of the SNPs rs6466686-rs4295599-rs12531086 (P = 6.51×10–8). The association of alcohol consumption was successfully replicated with rs4295599 in ANKRD7 gene in independent Caucasian nuclear families and independent unrelated Chinese Hans, and with rs16836497 in CYTL1 gene in independent unrelated Caucasians. Meta-analyses based on both the GWAS and replication samples further supported the observed significant associations between the ANKRD7 or CYTL1 gene and alcohol consumption.
The evidence suggests that ANKRD7 and CYTL1 genes may play an important role in the variance in AD risk.
PMCID: PMC4174677  PMID: 22613542
alcohol dependence; ANKRD7; CYTL1; genome-wide association study
4.  Genome-wide association study of copy number variation identified gremlin1 as a candidate gene for lean body mass 
Journal of human genetics  2011;57(1):33-37.
Lean body mass (LBM) is a heritable trait predicting a series of health problems, such as osteoporotic fracture and sarcopenia. We aim to identify sequence variants associated with LBM by a genome-wide association study (GWAS) of copy number variants (CNVs). We genotyped genome-wide CNVs of 1627 individuals of the Chinese population with Affymetrix SNP6.0 genotyping platform, which comprised of 9 40 000 copy number probes. We then performed a GWAS of CNVs with lean mass at seven sites: left and right arms, left and right legs, total of limb, trunk and whole body. We identified a CNV that is associated with LBM variation at the genome-wide significance level (CNV2073, Bonferroni corrected P-value 0.002 at right arm). CNV2073 locates at chromosome 15q13.3, which has been implicated as a candidate region for LBM by our previous linkage studies. The nearest gene, gremlin1, has a key role in the regulation of skeletal muscle formation and repair. Our results suggest that the gremlin1 gene is a potentially important gene for LBM variation. Our findings also show the utility and efficacy of CNV as genetic markers in association studies.
PMCID: PMC4169267  PMID: 22048656
association; copy number variation; gremlin1 gene; lean body mass; 15q13.3
5.  Functional Relevance for Associations between Genetic Variants and Systemic Lupus Erythematosus 
PLoS ONE  2013;8(1):e53037.
Systemic lupus erythematosus (SLE) is a serious prototype autoimmune disease characterized by chronic inflammation, auto-antibody production and multi-organ damage. Recent association studies have identified a long list of loci that were associated with SLE with relatively high statistical power. However, most of them only established the statistical associations of genetic markers and SLE at the DNA level without supporting evidence of functional relevance. Here, using publically available datasets, we performed integrative analyses (gene relationship across implicated loci analysis, differential gene expression analysis and functional annotation clustering analysis) and combined with expression quantitative trait loci (eQTLs) results to dissect functional mechanisms underlying the associations for SLE. We found that 14 SNPs, which were significantly associated with SLE in previous studies, have cis-regulation effects on four eQTL genes (HLA-DQA1, HLA-DQB1, HLA-DQB2, and IRF5) that were also differentially expressed in SLE-related cell groups. The functional evidence, taken together, suggested the functional mechanisms underlying the associations of 14 SNPs and SLE. The study may serve as an example of mining publically available datasets and results in validation of significant disease-association results. Utilization of public data resources for integrative analyses may provide novel insights into the molecular genetic mechanisms underlying human diseases.
PMCID: PMC3544818  PMID: 23341919
6.  Mitochondria-wide Association Study of Common Variants in Osteoporosis 
Annals of human genetics  2011;75(5):569-574.
Many lines of evidence suggest that mitochondrial DNA (mtDNA) variants are involved in the pathogenesis of human complex diseases, especially for age-related disorders. Osteoporosis is a typical age-related complex disease. However, the role of mtDNA variants in the susceptibility of osteoporosis is largely unknown. In this study, we performed a mitochondria-wide association study for osteoporosis in Caucasians. A total of 445 mitochondrial single nucleotide polymorphisms (mtSNPs) were genotyped in a large sample of 2,286 unrelated Caucasian subjects by using the Affymetrix Genome-Wide SNP Array 6.0, and 72 mtSNPs survived the quality control. We first tested for association between single-mtSNP and bone mineral density (BMD), and identified that, a mtSNP within the NADH dehydrogenase 2 gene (ND2), mt4823 C/A polymorphism, was strongly associated with hip BMD (P = 2.05 × 10−4), even after conservative Bonferroni correction‥ The C allele of mt4823 was associated with reduced hip BMD and the effect size (β) was estimated to be ~0.044. Another SNP mt15885 within the Cytochrome b gene (Cytb) was found to be associated both with spine (P = 1.66×10−3) and hip BMD (P = 0.023). The T allele of mt15885 had a protective effect on spine (β = 0.064) and hip BMD (β = 0.038). Next, we classified subjects into the nine common European haplogroups and conducted association analyses. Subjects classified as haplogroup X had significantly lower mean hip BMD values than others (P = 0.040). Our results highlighted the importance of mtDNA variants in influencing BMD variation and risk to osteoporosis.
PMCID: PMC3155639  PMID: 21762117
mtSNP; haplogroup; osteoporosis; BMD; association
7.  Polymorphisms in Predicted miRNA Binding Sites and Osteoporosis 
MicroRNAs (miRNAs) regulate posttranscriptional gene expression usually by binding to 3'-untranslated regions (3'-UTRs) of target message RNAs (mRNAs). Hence genetic polymorphisms on 3'-UTRs of mRNAs may alter binding affinity between miRNAs target 3'-UTRs, thereby altering translational regulation of target mRNAs and/or degradation of mRNAs, leading to differential protein expression of target genes. Based on a database that catalogues predicted polymorphisms in miRNA target sites (poly-miRTSs), we selected 568 polymorphisms within 3'-UTRs of target mRNAs and performed association analyses between these selected poly-miRTSs and osteoporosis in 997 white subjects who were genotyped by Affymetrix Human Mapping 500K arrays. Initial discovery (in the 997 subjects) and replication (in 1728 white subjects) association analyses identified three poly-miRTSs (rs6854081, rs1048201, and rs7683093) in the fibroblast growth factor 2 (FGF2) gene that were significantly associated with femoral neck bone mineral density (BMD). These three poly-miRTSs serve as potential binding sites for 9 miRNAs (eg, miR-146a and miR-146b). Further gene expression analyses demonstrated that the FGF2 gene was differentially expressed between subjects with high versus low BMD in three independent sample sets. Our initial and replicate association studies and subsequent gene expression analyses support the conclusion that these three polymorphisms of the FGF2 gene may contribute to susceptibility to osteoporosis, most likely through their effects on altered binding affinity for specific miRNAs. © 2011 American Society for Bone and Mineral Research.
PMCID: PMC3179316  PMID: 20641033
8.  Bivariate Genome-Wide Association Analyses of Femoral Neck Bone Geometry and Appendicular Lean Mass 
PLoS ONE  2011;6(11):e27325.
Femoral neck geometric parameters (FNGPs), such as periosteal diameter (W), cross-sectional area (CSA), cortical thickness (CT), buckling ratio (BR), and section modulus (Z), are highly genetically correlated with body lean mass. However, the specific SNPs/genes shared by these phenotypes are largely unknown.
To identify the specific SNPs/genes shared between FNGPs and appendicular lean mass (ALM), we performed an initial bivariate genome-wide association study (GWAS) by scanning ∼690,000 SNPs in 1,627 unrelated Han Chinese adults (802 males and 825 females) and a follow-up replicate study in 2,286 unrelated US Caucasians.
We identified 13 interesting SNPs that may be important for both FNGPs and ALM. Two SNPs, rs681900 located in the HK2 (hexokinase 2) gene and rs11859916 in the UMOD (uromodulin) gene, were bivariately associated with FNGPs and ALM (p = 7.58×10−6 for ALM-BR and p = 2.93×10−6 for ALM-W, respectively). The associations were then replicated in Caucasians, with corresponding p values of 0.024 for rs681900 and 0.047 for rs11859916. Meta-analyses yielded combined p values of 3.05×10−6 and 2.31×10−6 for rs681900 and rs11859916, respectively. Our findings are consistent with previous biological studies that implicated HK2 and UMOD in both FNGPs and ALM. Our study also identified a group of 11 contiguous SNPs, which spanned a region of ∼130 kb, were bivariately associated with FNGPs and ALM, with p values ranging from 3.06×10−7 to 4.60×10−6 for ALM-BR. The region contained two neighboring miRNA coding genes, MIR873 (MicroRNA873) and MIR876 (MicroRNA876).
Our study implicated HK2, UMOD, MIR873 and MIR876, as pleiotropic genes underlying variation of both FNGPs and ALM, thus suggesting their important functional roles in co-regulating both FNGPs and ALM.
PMCID: PMC3210160  PMID: 22087292
9.  Copy Number Variation in CNP267 Region May Be Associated with Hip Bone Size 
PLoS ONE  2011;6(7):e22035.
Osteoporotic hip fracture (HF) is a serious global public health problem associated with high morbidity and mortality. Hip bone size (BS) has been identified as one of key measurable risk factors for HF, independent of bone mineral density (BMD). Hip BS is highly genetically determined, but genetic factors underlying BS variation are still poorly defined. Here, we performed an initial genome-wide copy number variation (CNV) association analysis for hip BS in 1,627 Chinese Han subjects using Affymetrix GeneChip Human Mapping SNP 6.0 Array and a follow-up replicate study in 2,286 unrelated US Caucasians sample. We found that a copy number polymorphism (CNP267) located at chromosome 2q12.2 was significantly associated with hip BS in both initial Chinese and replicate Caucasian samples with p values of 4.73E-03 and 5.66E-03, respectively. An important candidate gene, four and a half LIM domains 2 (FHL2), was detected at the downstream of CNP267, which plays important roles in bone metabolism by binding to several bone formation regulator, such as insulin-like growth factor-binding protein 5 (IGFBP-5) and androgen receptor (AR). Our findings suggest that CNP267 region may be associated with hip BS which might influence the FHL2 gene downstream.
PMCID: PMC3137628  PMID: 21789208
10.  Pathway-Based Genome-Wide Association Analysis Identified the Importance of Regulation-of-Autophagy Pathway for Ultradistal Radius BMD 
Journal of Bone and Mineral Research  2010;25(7):1572-1580.
Wrist fracture is not only one of the most common osteoporotic fractures but also a predictor of future fractures at other sites. Wrist bone mineral density (BMD) is an important determinant of wrist fracture risk, with high heritability. Specific genes underlying wrist BMD variation are largely unknown. Most published genome-wide association studies (GWASs) have focused only on a few top-ranking single-nucleotide polymorphisms (SNPs)/genes and considered each of the identified SNPs/genes independently. To identify biologic pathways important to wrist BMD variation, we used a novel pathway-based analysis approach in our GWAS of wrist ultradistal radius (UD) BMD, examining approximately 500,000 SNPs genome-wide from 984 unrelated whites. A total of 963 biologic pathways/gene sets were analyzed. We identified the regulation-of-autophagy (ROA) pathway that achieved the most significant result (p = .005, qfdr = 0.043, pfwer = 0.016) for association with UD BMD. The ROA pathway also showed significant association with arm BMD in the Framingham Heart Study sample containing 2187 subjects, which further confirmed our findings in the discovery cohort. Earlier studies indicated that during endochondral ossification, autophagy occurs prior to apoptosis of hypertrophic chondrocytes, and it also has been shown that some genes in the ROA pathway (e.g., INFG) may play important roles in osteoblastogenesis or osteoclastogenesis. Our study supports the potential role of the ROA pathway in human wrist BMD variation and osteoporosis. Further functional evaluation of this pathway to determine the mechanism by which it regulates wrist BMD should be pursued to provide new insights into the pathogenesis of wrist osteoporosis. © 2010 American Society for Bone and Mineral Research.
PMCID: PMC3153999  PMID: 20200951
osteoporosis; bone mineral density; genome-wide association; regulation of autophagy; whites
11.  Genetic Association Study of Common Mitochondrial Variants on Body Fat Mass 
PLoS ONE  2011;6(6):e21595.
Mitochondria play a central role in ATP production and energy metabolism. Previous studies suggest that common variants in mtDNA are associated with several common complex diseases, including obesity. To test the hypothesis that common mtDNA variants influence obesity-related phenotypes, including BMI and body fat mass, we genotyped a total of 445 mtSNPs across the whole mitochondrial genome in a large sample of 2,286 unrelated Caucasian subjects. 72 of these 445 mtSNPs passed quality control criteria, and were used for subsequent analyses. We also classified all subjects into nine common European haplogroups. Association analyses were conducted for both BMI and body fat mass with single mtSNPs and mtDNA haplogroups. Two mtSNPs, mt4823 and mt8873 were detected to be significantly associated with body fat mass, with adjusted P values of 4.94×10-3 and 4.58×10-2, respectively. The minor alleles mt4823 C and mt8873 A were associated with reduced fat mass values and the effect size (β) was estimated to be 3.52 and 3.18, respectively. These two mtSNPs also achieved nominally significant levels for association with BMI. For haplogroup analyses, we found that haplogroup X was strongly associated with both BMI (adjusted P = 8.31×10-3) and body fat mass (adjusted P = 5.67×10-4) Subjects classified as haplogroup X had lower BMI and fat mass values, with the β estimated to be 2.86 and 6.03, respectively. Our findings suggest that common variants in mitochondria might play a role in variations of body fat mass. Further molecular and functional studies will be needed to clarify the potential mechanism.
PMCID: PMC3126834  PMID: 21747914
12.  Impaired Osteoblast Function in GPRC6A Null Mice 
Journal of Bone and Mineral Research  2009;25(5):1092-1102.
GPRC6A is a widely expressed orphan G protein–coupled receptor that senses extracellular amino acids, osteocalcin, and divalent cations in vitro. GPRC6A null (GPRC6A−/−) mice exhibit multiple metabolic abnormalities including osteopenia. To investigate whether the osseous abnormalities are a direct function of GPRC6A in osteoblasts, we examined the function of primary osteoblasts and bone marrow stromal cell cultures (BMSCs) in GPRC6A−/− mice. We confirmed that GPRC6A−/− mice exhibited a decrease in bone mineral density (BMD) associated with reduced expression of osteocalcin, ALP, osteoprotegerin, and Runx2-II transcripts in bone. Osteoblasts and BMSCs derived from GPRC6A−/− mice exhibited an attenuated response to extracellular calcium-stimulated extracellular signal-related kinase (ERK) activation, diminished alkaline phosphatase (ALP) expression, and impaired mineralization ex vivo. In addition, siRNA-mediated knockdown of GPRC6A in MC3T3 osteoblasts also resulted in a reduction in extracellular calcium-stimulated ERK activity. To explore the potential relevance of GPRC6A function in humans, we looked for an association between GPRC6A gene polymorphisms and BMD in a sample of 1000 unrelated American Caucasians. We found that GPRC6A gene polymorphisms were significantly associated with human spine BMD. These data indicate that GRPC6A directly participates in the regulation of osteoblast-mediated bone mineralization and may mediate the anabolic effects of extracellular amino acids, osteocalcin, and divalent cations in bone. © 2010 American Society for Bone and Mineral Research.
PMCID: PMC3153369  PMID: 19874200
GPRC6A; G protein–coupled receptor (GPCR); osteoblast; bone mineral density; gene polymorphisms
13.  Genome-Wide Association Study for Femoral Neck Bone Geometry 
Poor femoral neck bone geometry at the femur is an important risk factor for hip fracture. We conducted a genome-wide association study (GWAS) of femoral neck bone geometry, examining approximately 379,000 eligible single-nucleotide polymorphisms (SNPs) in 1000 Caucasians. A common genetic variant, rs7430431 in the receptor transporting protein 3 (RTP3) gene, was identified in strong association with the buckling ratio (BR, P = 1.6 × 10−7), an index of bone structural instability, and with femoral cortical thickness (CT, P = 1.9 × 10−6). The RTP3 gene is located in 3p21.31, a region that we found to be linked with CT (LOD = 2.19, P = 6.0 × 10−4) in 3998 individuals from 434 pedigrees. The replication analyses in 1488 independent Caucasians and 2118 Chinese confirmed the association of rs7430431 to BR and CT (combined P = 7.0 × 10−3 for BR and P = 1.4 × 10−2 for CT). In addition, 350 hip fracture patients and 350 healthy control individuals were genotyped to assess the association of the RTP3 gene with the risk of hip fracture. Significant association between a nearby common SNP, rs10514713 of the RTP3 gene, and hip fracture (P = 1.0 × 10−3) was found. Our observations suggest that RTP3 may be a novel candidate gene for femoral neck bone geometry. © 2010 American Society for Bone and Mineral Research
PMCID: PMC3153387  PMID: 20175129
genome-wide association; femoral neck bone geometry; bone fracture; RTP3
14.  Gene Expression Profiling in Monocytes and SNP Association Suggest the Importance of the Gene for Osteoporosis in Both Chinese and Caucasians 
Osteoporosis is characterized mainly by low bone mineral density (BMD). Many cytokines and chemokines have been related with bone metabolism. Monocytes in the immune system are important sources of cytokines and chemokines for bone metabolism. However, no study has investigated in vivo expression of a large number of various factors simultaneously in human monocytes underlying osteoporosis. This study explored the in vivo expression pattern of general cytokines, chemokines, and their receptor genes in human monocytes and validated the significant genes by qRT-PCR and genetic association analyses. Expression profilings were performed in monocyte samples from 26 Chinese and 20 Caucasian premenopausal women with discordant BMD. Genome-wide association analysis with BMD variation was conducted in 1000 unrelated Caucasians. We selected 168 cytokines, chemokines, osteoclast-related factors, and their receptor genes for analyses. Significantly, the signal transducer and activator of transcription 1 (STAT1) gene was upregulated in the low versus the high BMD groups in both Chinese and Caucasians. We also revealed a significant association of the STAT1 gene with BMD variation in the 1000 Caucasians. Thus we conclude that the STAT1 gene is important in human circulating monocytes in the etiology of osteoporosis. © 2010 American Society for Bone and Mineral Research.
PMCID: PMC3153389  PMID: 19594299
STAT1; bmd; monocytes; osteoporosis; microarray; SNP
15.  Genome-wide association study identifies two novel loci containing FLNB and SBF2 genes underlying stature variation 
Human Molecular Genetics  2008;18(9):1661-1669.
Human stature, as an important physical index in clinical practice and a usual covariate in gene mapping of complex disorders, is a highly heritable complex trait. To identify specific genes underlying stature, a genome-wide association study was performed in 1000 unrelated homogeneous Caucasian subjects using Affymetrix 500K arrays. A group of seven contiguous markers in the region of SBF2 gene (Set-binding factor 2) are associated with stature, significantly so at the genome-wide level after false discovery rate (FDR) correction (FDR q = 0.034–0.042). Three SNPs in another SNP group in the Filamin B (FLNB) gene were also associated with stature, significantly so with FDR q = 0.042–0.048. In follow-up independent replication studies, rs10734652 in the SBF2 gene was significantly (P = 0.036) and suggestively (P = 0.07) associated with stature in Caucasian families and 1306 unrelated Caucasian subjects, respectively, and rs9834312 in the FLNB gene was also associated with stature in such two independent Caucasian populations (P = 0.008 in unrelated sample and P = 0.049 in family sample). Particularly, additional significant replication association signals were detected in Chinese, an ethnic population different from Caucasian, between rs9834312 and stature in 619 unrelated northern Chinese subjects (P = 0.017), as well as between rs10734652 and stature in 2953 unrelated southern Chinese subjects (P = 0.048). This study also provides additional replication evidence for some of the already published stature loci. These results, together with the known functional relevance of the SBF2 and FLNB genes to skeletal linear growth and bone formation, support that two regions containing FLNB and SBF2 genes are two novel loci underlying stature variation.
PMCID: PMC2667283  PMID: 19039035
16.  Genome-Wide Association Study Identifies ALDH7A1 as a Novel Susceptibility Gene for Osteoporosis 
PLoS Genetics  2010;6(1):e1000806.
Osteoporosis is a major public health problem. It is mainly characterized by low bone mineral density (BMD) and/or low-trauma osteoporotic fractures (OF), both of which have strong genetic determination. The specific genes influencing these phenotypic traits, however, are largely unknown. Using the Affymetrix 500K array set, we performed a case-control genome-wide association study (GWAS) in 700 elderly Chinese Han subjects (350 with hip OF and 350 healthy matched controls). A follow-up replication study was conducted to validate our major GWAS findings in an independent Chinese sample containing 390 cases with hip OF and 516 controls. We found that a SNP, rs13182402 within the ALDH7A1 gene on chromosome 5q31, was strongly associated with OF with evidence combined GWAS and replication studies (P = 2.08×10−9, odds ratio = 2.25). In order to explore the target risk factors and potential mechanism underlying hip OF risk, we further examined this candidate SNP's relevance to hip BMD both in Chinese and Caucasian populations involving 9,962 additional subjects. This SNP was confirmed as consistently associated with hip BMD even across ethnic boundaries, in both Chinese and Caucasians (combined P = 6.39×10−6), further attesting to its potential effect on osteoporosis. ALDH7A1 degrades and detoxifies acetaldehyde, which inhibits osteoblast proliferation and results in decreased bone formation. Our findings may provide new insights into the pathogenesis of osteoporosis.
Author Summary
Osteoporosis is a major health concern worldwide. It is a highly heritable disease characterized mainly by low bone mineral density (BMD) and/or osteoporotic fractures. However, the specific genetic variants determining risk for low BMD or OF are largely unknown. Here, taking advantage of recent technological advances in human genetics, we performed a genome-wide association study and follow-up validation studies to identify genetic variants for osteoporosis. By examining a total of 11,568 individuals from Chinese and Caucasian populations, we discovered a susceptibility gene, ALDH7A1, which is associated with hip osteoporotic fracture and BMD. ALDH7A1 might inhibit osteoblast proliferation and decrease bone formation. Our finding opens a new avenue for exploring the pathophysiology of osteoporosis.
PMCID: PMC2794362  PMID: 20072603
17.  Proteomic analysis of circulating monocytes in Chinese premenopausal females with extremely discordant bone mineral density 
Proteomics  2008;8(20):4259-4272.
Osteoporosis (OP) is a major public health problem, mainly characterized by low bone mineral density (BMD). Circulating monocytes (CMCs) may serve as progenitors of osteoclasts and produce a wide variety of factors important to bone metabolism. However, the specific action mechanism of CMCs in the pathogenesis of OP is far from clear. We performed a comparative protein expression profiling study of CMCs in Chinese premenopausal females with extremely discordant BMD, identified a total of 38 differentially expressed proteins, and confirmed with Western blotting five proteins: ras suppressor protein1 (RSU1), gelsolin (GSN), manganese-containing superoxide dismutase (SOD2), glutathione peroxidase 1(GPX1), and prolyl 4-hydroxylase β subunit (P4HB). These proteins might affect CMCs’ trans-endothelium, differentiation, and/or downstream osteoclast functions, thus contribute to differential osteoclastogenesis and finally lead to BMD variation. The findings promote our understanding of the role of CMCs in BMD determination, and provide an insight into the pathogenesis of human OP.
PMCID: PMC2760933  PMID: 18924182
Bone mineral density; Circulating monocyte; Osteoclastogenesis; Protein
18.  Genome-wide association scan for stature in Chinese: evidence for ethnic specific loci 
Human genetics  2008;125(1):1-9.
In Caucasian, several studies have identified some common variants associated with human stature variation. However, no such study was performed in Chinese, which is the largest population in the world and evidently differs from Caucasian in genetic background. To identify common or ethnic specific genes for stature in Chinese, an initial GWAS and follow-up replication study were performed. Our initial GWAS study found that a group of 13 contiguous SNPs, which span a region of ∼150 kb containing two neighboring genes, zinc finger protein (ZNP) 510 and ZNP782, achieved strong signals for association with stature, with P values ranging from 9.71 × 10−5 to 3.11 × 10−6. After false discovery rate correction for multiple testing, 9 of the 13 SNPs remain significant (FDR q = 0.036–0.046). The follow-up replication study in an independent 2,953 unrelated southern Chinese confirmed the association of rs10816533 with stature (P = 0.029). All the13 SNPs were in consistently strong linkage disequilibrium (D′ > 0.99) and formed a single perfect haplotype block. The minor allele frequencies for the 13 contiguous SNPs have evidently ethnic difference, which range from 0.21 to 0.33 in Chinese but have as low as ∼0.017 reported in dbSNP database in Caucasian. The present results suggest that the genomic region containing the ZNP510 and ZNP782 genes is an ethnic specific locus associated with stature variation in Chinese.
PMCID: PMC2730511  PMID: 19030899
19.  Genome-Wide Association Analyses Identify SPOCK as a Key Novel Gene Underlying Age at Menarche 
PLoS Genetics  2009;5(3):e1000420.
For females, menarche is a most significant physiological event. Age at menarche (AAM) is a trait with high genetic determination and is associated with major complex diseases in women. However, specific genes for AAM variation are largely unknown. To identify genetic factors underlying AAM variation, a genome-wide association study (GWAS) examining about 380,000 SNPs was conducted in 477 Caucasian women. A follow-up replication study was performed to validate our major GWAS findings using two independent Caucasian cohorts with 854 siblings and 762 unrelated subjects, respectively, and one Chinese cohort of 1,387 unrelated subjects—all females. Our GWAS identified a novel gene, SPOCK (Sparc/Osteonectin, CWCV, and Kazal-like domains proteoglycan), which had seven SNPs associated with AAM with genome-wide false discovery rate (FDR) q<0.05. Six most significant SNPs of the gene were selected for validation in three independent replication cohorts. All of the six SNPs were replicated in at least one cohort. In particular, SNPs rs13357391 and rs1859345 were replicated both within and across different ethnic groups in all three cohorts, with p values of 5.09×10−3 and 4.37×10−3, respectively, in the Chinese cohort and combined p values (obtained by Fisher's method) of 5.19×10−5 and 1.02×10−4, respectively, in all three replication cohorts. Interestingly, SPOCK can inhibit activation of MMP-2 (matrix metalloproteinase-2), a key factor promoting endometrial menstrual breakdown and onset of menstrual bleeding. Our findings, together with the functional relevance, strongly supported that the SPOCK gene underlies variation of AAM.
Author Summary
Menarche is a physical milestone in a woman's life. Age at menarche (AAM) is related to many common female health problems. AAM is mainly determined by genetic factors. However, the specific genes and the associated mechanisms underlying AAM are largely unknown. Here, taking advantage of the most recent technological advances in the field of human genetics, we identified multiple genetic variants in a gene, SPOCK, which are associated with AAM variation in a group of Caucasian women. This association was subsequently confirmed not only in two independent groups of Caucasian women but also across ethnic boundaries in one group of Chinese women. In addition, SPOCK has a function in regulating a key factor involved in menstrual cycles, MMP-2, which provides further support to our findings. Our study provides a solid basis for further investigation of the gene, which may help to reveal the underlying mechanisms for the timing of menarche and for AAM's relationship with women's health in general.
PMCID: PMC2652107  PMID: 19282985

Results 1-19 (19)