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1.  SNP rs6265 Regulates Protein Phosphorylation and Osteoblast Differentiation and Influences BMD in Humans 
Bone Mineral Density (BMD) is major index for diagnosing osteoporosis. PhosSNPs are non-synonymous SNPs that affect protein phosphorylation. The relevance and significance of phosSNPs to BMD and osteoporosis is unknown. This study aims to identify and characterize phosSNPs significant for BMD in humans. We conducted a pilot genome-wide phosSNP association study for BMD in three independent population samples, involving ~5,000 unrelated individuals. We identified and replicated three phosSNPs associated with both spine BMD and hip BMD in Caucasians. Association with hip BMD for one of these phosSNPs, i.e., rs6265 (major/minor allele: G/A) in BDNF gene, was also suggested in Chinese. Consistently in both ethnicities, individuals carrying AA genotype have significant lower hip BMD than carriers of GA and GG genotypes. Through in vitro molecular and cellular studies, we found that compared to osteoblastic cells transfected with wild-type BDNF-Val66 (encoded with allele G at rs6265), transfection of variant BDNF-Met66 (encoded with allele A at rs6265) significantly decreased BDNF protein phosphorylation (at amino acid residue T62), expression of osteoblastic genes (OPN, BMP2, and ALP), and osteoblastic activity. The findings are consistent with and explain our prior observations in general human populations. We conclude that phosSNP rs6265, via regulating BDNF protein phosphorylation and osteoblast differentiation, influence hip BMD in humans. This study represents our first endeavor to dissect the functions of phosSNPs in bone, which might stimulate extended large-scale studies on bone or similar studies on other human complex traits and diseases.
PMCID: PMC4127979  PMID: 23712400
BMD; SNP; protein phosphorylation; BDNF; osteoblast
2.  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
3.  Genome-Wide Association Study Identified UQCC Locus for Spine Bone Size in Humans 
Bone  2012;53(1):129-133.
Bone size (BS) contributes significantly to the risk of osteoporotic fracture. Osteoporotic spine fracture is one of the most disabling outcomes of osteoporosis. This study aims to identify genomic loci underlying spine BS variation in humans.
We performed a genome-wide association scan in 2,286 unrelated Caucasians using Affymetrix 6.0 SNP arrays. Areal BS (cm2) at lumbar spine was measured using dual energy X-ray absorptiometry scanners. SNPs of interest were subjected to replication analyses and meta-analyses with additional two independent Caucasian populations (N = 1,000 and 2,503) and one Chinese population (N = 1,627).
In the initial GWAS, 91 SNPs were associated with spine BS (P<1.0E-4). Eight contiguous SNPs were found clustering in a haplotype block within UQCC gene (ubiquinol-cytochrome creductase complex chaperone). Association of the above eight SNPs with spine BS were replicated in one Caucasian and one Chinese populations. Meta-analyses (N = 7,416) generated much stronger association signals for these SNPs (e.g., P = 1.86E-07 for SNP rs6060373), supporting association of UQCC with spine BS across ethnicities.
This study identified a novel locus, i.e., the UQCC gene, for spine BS variation in humans. Future functional studies will contribute to elucidating the mechanisms by which UQCC regulates bone growth and development.
PMCID: PMC3682469  PMID: 23207799
Spine bone size; GWAS; UQCC
4.  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
5.  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
6.  Genome-Wide Association Study Identified CNP12587 Region Underlying Height Variation in Chinese Females 
PLoS ONE  2012;7(9):e44292.
Human height is a highly heritable trait considered as an important factor for health. There has been limited success in identifying the genetic factors underlying height variation. We aim to identify sequence variants associated with adult height by a genome-wide association study of copy number variants (CNVs) in Chinese.
Genome-wide CNV association analyses were conducted in 1,625 unrelated Chinese adults and sex specific subgroup for height variation, respectively. Height was measured with a stadiometer. Affymetrix SNP6.0 genotyping platform was used to identify copy number polymorphisms (CNPs). We constructed a genomic map containing 1,009 CNPs in Chinese individuals and performed a genome-wide association study of CNPs with height.
We detected 10 significant association signals for height (p<0.05) in the whole population, 9 and 11 association signals for Chinese female and male population, respectively. A copy number polymorphism (CNP12587, chr18:54081842-54086942, p = 2.41×10−4) was found to be significantly associated with height variation in Chinese females even after strict Bonferroni correction (p = 0.048). Confirmatory real time PCR experiments lent further support for CNV validation. Compared to female subjects with two copies of the CNP, carriers of three copies had an average of 8.1% decrease in height. An important candidate gene, ubiquitin-protein ligase NEDD4-like (NEDD4L), was detected at this region, which plays important roles in bone metabolism by binding to bone formation regulators.
Our findings suggest the important genetic variants underlying height variation in Chinese.
PMCID: PMC3434125  PMID: 22957059
7.  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
8.  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
9.  Genome-wide Copy Number Variation Association Study Suggested VPS13B Gene for Osteoporosis in Caucasian 
Bone mineral density (BMD) and femoral neck cross-sectional geometric parameters (FNCSGPs) are under strong genetic control. DNA copy number variation (CNV) is an important source of genetic diversity for human diseases. This study aims to identify CNVs associated with BMD and FNCSGPs.
Genome-wide CNV association analyses were conducted in 1,000 unrelated Caucasian subjects for BMD at the spine, hip, femoral neck, and for three FNCSGPs - cortical thickness (CT), cross section area (CSA), and buckling ratio (BR). BMD was measured by dual energy X-ray absorptiometry (DEXA). CT, CSA, and BR were estimated using DEXA measurements. Affymetrix 500K arrays and copy number analysis tool was used to identify CNVs.
A CNV in VPS13B gene was significantly associated with spine, hip and FN BMDs, and CT, CSA, and BR (p < 0.05). Compared to subjects with 2 copies of the CNV, carriers of one copy had an average of 14.6%, 12.4%, and 13.6% higher spine, hip, and FN BMD, 20.0% thicker CT, 10.6% larger CSA, and 12.4% lower BR. Thus a decrease of the CNV consistently produced stronger bone, thereby reducing osteoporotic fracture risk.
VPS13B gene, via affecting BMD and FNCSGPs, is a novel osteoporosis risk gene
PMCID: PMC2924432  PMID: 19680589
copy number variation; bone mineral density; bone geometry; osteoporosis
10.  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
11.  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
12.  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 1-12 (12)