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1.  Post-Receptor Crosstalk between Growth Hormone and Insulin Signal in Rats Born Small for Gestational Age with Catch-Up Growth 
PLoS ONE  2014;9(6):e100459.
Insulin resistance has been observed in individuals born small for gestational age (SGA) with catch-up growth (CUG), yet the mechanisms involved remain unclear. This study examined the role of GH and insulin signaling crosstalk in insulin resistance of SGA rats with CUG.
Design and Methods
SGA rats were developed by dietary restriction in pregnant rats. GH receptor inhibition was performed on four-week old CUG-SGA and AGA rats. Phosphorylation of IRS-1, AKT, and ERK, and expression of SOCS3 in the skeletal muscle were determined via immunoblot analysis at baseline and after insulin stimulation in CUG-SGA, NCUG-SGA and AGA groups.
Compared to AGA controls, phosphorylation of IRS-1 and AKT in response to insulin stimulation in CUG-SGA rats was significantly blunted (P<0.05), and phosphorylation of ERK at baseline was dramatically activated (P<0.05). SOCS3 expression was significantly increased in CUG-SGA compared to AGA (P = 0.001) and NCUG-SGA (P = 0.006) rats, and was significantly suppressed following GHR inhibition (P<0.05). Furthermore, phosphorylation of IRS-1 and AKT in response to insulin stimulation increased after GHR inhibition (P<0.05).
Insulin resistance in CUG-SGA rats is associated with impairment of IRS-1-PI3K-AKT signaling, which may result from GH signaling-induced up-regulation of SOCS3.
PMCID: PMC4070916  PMID: 24963636
2.  Insulin resistance and adiponectin levels are associated with height catch-up growth in pre-pubertal Chinese individuals born small for gestational age 
Background and objective
The study was performed to determine whether catch-up growth is associated with the development of insulin resistance and to explore serum endocrine markers associated with the metabolism of adipose tissue in a Chinese population born small for gestational age(SGA)
Subjects and methods
We recruited 56 children born SGA with catch-up growth and 55 born without catch-up growth, who were further grouped into groups I (with BMI catch-up) and II (without BMI catch-up) respectively, as well as 52 children born appropriate for gestational age (AGA) with normal height. Their serum fasting insulin, fasting glucose, insulin-like growth factor-1, adiponectin, IGFBP-1, triglyceride concentrations, and the homeostasis assessment model for insulin resistance (HOMA-IR) were evaluated.
(1) The HOMA-IR values in SGA-I with catch-up growth group were significantly higher than those in SGA-II with catch-up growth, SGA-I without catch-up growth and AGA children respectively. (2) The serum adiponectin levels of individuals in the SGA-I without catch-up growth and SGA-II with catch-up growth groups were significantly lower than those from the SGA-II without catch-up growth group. There was no difference in triglyceride or IGFBP-1 levels among the groups. (3) The degree of HOMA-IR was positively correlated with age, current BMI and △height SDS in SGA children.
The development of insulin resistance and lower levels of adiponectin were closely correlated with higher BMI and the postnatal height catch-up growth in SGA children.
PMCID: PMC3574033  PMID: 23186039
Small for gestational age; Catch-up growth; Insulin resistance; Adiponectin
3.  Genetic Analysis Identifies DDR2 as a Novel Gene Affecting Bone Mineral Density and Osteoporotic Fractures in Chinese Population 
PLoS ONE  2015;10(2):e0117102.
DDR2 gene, playing an essential role in regulating osteoblast differentiation and chondrocyte maturation, may influence bone mineral density (BMD) and osteoporosis, but the genetic variations actually leading to the association remain to be elucidated. Therefore, the aim of this study was to investigate whether the genetic variants in DDR2 are associated with BMD and fracture risk. This study was performed in three samples from two ethnicities, including 1,300 Chinese Han subjects, 700 Chinese Han subjects (350 with osteoporotic hip fractures and 350 healthy controls) and 2,286 US white subjects. Twenty-eight SNPs in DDR2 were genotyped and tested for associations with hip BMD and fractures. We identified 3 SNPs in DDR2 significantly associated with hip BMD in the Chinese population after multiple testing adjustments, which were rs7521233 (P = 1.06×10−4, β: −0.018 for allele C), rs7553831 (P = 1.30×10−4, β: −0.018 for allele T), and rs6697469 (P = 1.59×10−3, β: −0.015 for allele C), separately. These three SNPs were in high linkage disequilibrium. Haplotype analyses detected two significantly associated haplotypes, including one haplotype in block 2 (P = 9.54×10−4, β: −0.016) where these three SNPs located. SNP rs6697469 was also associated with hip fractures (P = 0.043, OR: 1.42) in the Chinese population. The effect on fracture risk was consistent with its association with lower BMD. However, in the white population, we didn’t observe significant associations with hip BMD. eQTL analyses revealed that SNPs associated with BMD also affected DDR2 mRNA expression levels in Chinese. Our findings, together with the prior biological evidence, suggest that DDR2 could be a new candidate for osteoporosis in Chinese population. Our results also reveal an ethnic difference, which highlights the need for further genetic studies in each ethnic group.
PMCID: PMC4319719  PMID: 25658585
4.  Attenuated Monocyte Apoptosis, a New Mechanism for Osteoporosis Suggested by a Transcriptome-Wide Expression Study of Monocytes 
PLoS ONE  2015;10(2):e0116792.
Osteoporosis is caused by excessive bone resorption (by osteoclasts) over bone formation (by osteoblasts). Monocytes are important to osteoporosis by serving as progenitors of osteoclasts and produce cytokines for osteoclastogenesis.
To identify osteoporosis-related genes, we performed microarray analyses of monocytes using Affymetrix 1.0 ST arrays in 42 (including 16 pre- and 26 postmenopausal) high hip BMD (bone mineral density) vs. 31 (including 15 pre- and 16 postmenopausal) low hip BMD Caucasian female subjects. Here, high vs. low BMD is defined as belonging to top vs. bottom 30% of BMD values in population.
Differential gene expression analysis in high vs. low BMD subjects was conducted in the total cohort as well as pre- and post-menopausal subjects. Focusing on the top differentially expressed genes identified in the total, the pre- and the postmenopausal subjects (with a p <5E-03), we performed replication of the findings in 3 independent datasets of microarray analyses of monocytes (total N = 125).
We identified (in the 73 subjects) and successfully replicated in all the 3 independent datasets 2 genes, DAXX and PLK3. Interestingly, both genes are apoptosis induction genes and both down-regulated in the low BMD subjects. Moreover, using the top 200 genes identified in the meta-analysis across all of the 4 microarray datasets, GO term enrichment analysis identified a number of terms related to induction of apoptosis, for which the majority of component genes are also down-regulated in the low BMD subjects. Overall, our result may suggest that there might be a decreased apoptosis activity of monocytes in the low BMD subjects.
Our study for the first time suggested a decreased apoptosis rate (hence an increased survival) of monocytes, an important osteoclastogenic cell, as a novel mechanism for osteoporosis.
PMCID: PMC4319757  PMID: 25659073
5.  B7-H1–expressing antigen-presenting cells mediate polarization of protumorigenic Th22 subsets 
The Journal of Clinical Investigation  2014;124(10):4657-4667.
Classical IL-22–producing T helper cells (Th22 cells) mediate inflammatory responses independently of IFN-γ and IL-17; however, nonclassical Th22 cells have been recently identified and coexpress IFN-γ and/or IL-17 along with IL-22. Little is known about how classical and nonclassical Th22 subsets in human diseases are regulated. Here, we used samples of human blood, normal and peritumoral liver, and hepatocellular carcinoma (HCC) to delineate the phenotype, distribution, generation, and functional relevance of various Th22 subsets. Three nonclassical Th22 subsets constituted the majority of all Th22 cells in human liver and HCC tissues, although the classical Th22 subset was predominant in blood. Monocytes activated by TLR2 and TLR4 agonists served as the antigen-presenting cells (APCs) that most efficiently triggered the expansion of nonclassical Th22 subsets from memory T cells and classical Th22 subsets from naive T cells. Moreover, B7-H1–expressing monocytes skewed Th22 polarization away from IFN-γ and toward IL-17 through interaction with programmed death 1 (PD-1), an effect that can create favorable conditions for in vivo aggressive cancer growth and angiogenesis. Our results provide insight into the selective modulation of Th22 subsets and suggest that strategies to influence functional activities of inflammatory cells may benefit anticancer therapy.
PMCID: PMC4191045  PMID: 25244097
6.  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
7.  Characterization of Human Chromosomal Material Exchange with Regard to the Chromosome Translocations Using Next-Generation Sequencing Data 
Genome Biology and Evolution  2014;6(11):3015-3024.
As an important subtype of structural variations, chromosomal translocation is associated with various diseases, especially cancers, by disrupting gene structures and functions. Traditional methods for identifying translocations are time consuming and have limited resolutions. Recently, a few studies have employed next-generation sequencing (NGS) technology for characterizing chromosomal translocations on human genome, obtaining high-throughput results with high resolutions. However, these studies are mainly focused on mechanism-specific or site-specific translocation mapping. In this study, we conducted a comprehensive genome-wide analysis on the characterization of human chromosomal material exchange with regard to the chromosome translocations. Using NGS data of 1,481 subjects from the 1000 Genomes Project, we identified 15,349,092 translocated DNA fragment pairs, ranging from 65 to 1,886 bp and with an average size of approximately 102 bp. On average, each individual genome carried about 10,364 pairs, covering approximately 0.069% of the genome. We identified 16 translocation hot regions, among which two regions did not contain repetitive fragments. Results of our study overlapped with a majority of previous results, containing approximately 79% of approximately 2,340 translocations characterized in three available translocation databases. In addition, our study identified five novel potential recurrent chromosomal material exchange regions with greater than 20% detection rates. Our results will be helpful for an accurate characterization of translocations in human genomes, and contribute as a resource for future studies of the roles of translocations in human disease etiology and mechanisms.
PMCID: PMC4255766  PMID: 25349267
chromosomal translocation; next-generation sequencing; recurrent translocation; structural variation
8.  Mutant ZP1 in Familial Infertility 
The New England journal of medicine  2014;370(13):1220-1226.
The human zona pellucida is composed of four glycoproteins (ZP1, ZP2, ZP3, and ZP4) and has an important role in reproduction. Here we describe a form of infertility with an autosomal recessive mode of inheritance, characterized by abnormal eggs that lack a zona pellucida. We identified a homozygous frameshift mutation in ZP1 in six family members. In vitro studies showed that defective ZP1 proteins and normal ZP3 proteins colocalized throughout the cells and were not expressed at the cell surface, suggesting that the aberrant ZP1 results in the sequestration of ZP3 in the cytoplasm, thereby preventing the formation of the zona pellucida around the oocyte.
PMCID: PMC4076492  PMID: 24670168
9.  Evaluation of Compressive Strength Index of the Femoral Neck in Caucasians and Chinese 
Calcified tissue international  2010;87(4):324-332.
Compressive strength index (CSI) of the femoral neck is a parameter that integrates the information of bone mineral density (BMD), femoral neck width (FNW), and body weight. CSI is considered to have the potential to improve the performance of assessment for hip fracture risk. However, studies on CSI have been rare. In particular, few studies have evaluated the performance of CSI, in comparison with BMD, FNW, and bending geometry, for assessment of hip fracture risk. We studied two large populations, including 1683 unrelated U.S. Caucasians and 2758 unrelated Chinese adults. For all the study subjects, CSI, femoral neck BMD (FN_BMD), FNW, and bending geometry (section modulus [Z]) of the samples were obtained from dual-energy X-ray absorptiometry scans. We investigated the age-related trends of these bone phenotypes and potential sex and ethnic differences. We further evaluated the performance of these four phenotypes for assessment of hip fracture risk by logistic regression models. Chinese had significantly lower FN_BMD, FNW, and Z, but higher CSI than sex-matched Caucasians. Logistic regression analysis showed that higher CSI was significantly associated with lower risk of hip fracture, and the significance remained after adjusting for covariates of age, sex, and height. Each standard deviation (SD) increment in CSI was associated with odds ratios of 0.765 (95% confidence interval, 0.634, 0.992) and 0.724 (95% confidence interval, 0.569, 0.921) for hip fracture risk in Caucasians and Chinese, respectively. The higher CSI in Chinese may partially help explain the lower incidence of hip fractures in this population compared to Caucasians. Further studies in larger cohorts and/or longitudinal observations are necessary to confirm our findings.
PMCID: PMC4176885  PMID: 20814670
Osteoporosis; Bone mineral density; Compressive strength index; Femoral neck width; Section modulus; Hip fracture
10.  Polymorphisms of the tumor necrosis factor-alpha receptor 2 gene are associated with obesity phenotypes among 405 Caucasian nuclear families 
Human genetics  2008;124(2):171-177.
The plasma level of the tumor necrosis factor-alpha receptor 2 (TNFR2) is associated with obesity phenotypes. However, the genetic polymorphisms for such an association have rarely been explored and are generally unknown. In this study, by employing a large sample of 1,873 subjects from 405 Caucasian nuclear families, we explored the association of 12 SNPs of the TNFR2 gene and obesity-related phenotypes, including body mass index (BMI), fat mass, and percentage fat mass (PFM). The within-family quantitative transmission disequilibrium test, which is robust to sample stratification, was implemented to evaluate the association of TNFR2 gene with obesity phenotypes. Evidence of association was obtained at SNP9 (rs5746059) with fat mass (P = 0.0002), BMI (P = 0.002), and PFM (P = 0.0006). The contribution of this polymorphism to the variation of fat mass and PFM was 6.24 and 7.82%, respectively. Individuals carrying allele A at the SNP9 site had a 4.6% higher fat mass and a 2.5% increased PFM compared to noncarriers. The results remained significant even after correction for multiple testing. Evidence of association between the TNFR2 gene and obesity phenotypes are also found in 700 independent Chinese Han and 1,000 random Caucasians samples. The results suggest that the TNFR2 gene polymorphisms contribute to the variation of obesity phenotypes.
PMCID: PMC4176887  PMID: 18685868
11.  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
12.  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
13.  Meta-analysis identifies a MECOM gene as a novel predisposing factor of osteoporotic fracture 
Journal of medical genetics  2013;50(4):212-219.
Osteoporotic fracture (OF) as a clinical endpoint is a major complication of osteoporosis. To screen for OF susceptibility genes, we performed a genome-wide association study and carried out de novo replication analysis of an East Asian population.
Association was tested using a logistic regression analysis. A meta-analysis was performed on the combined results using effect size and standard errors estimated for each study.
In a combined meta-analysis of a discovery cohort (288 cases and 1139 controls), three hospital based sets in replication stage I (462 cases and 1745 controls), and an independent ethnic group in replication stage II (369 cases and 560 for controls), we identified a new locus associated with OF (rs784288 in the MECOM gene) that showed genome-wide significance (p=3.59×10−8; OR 1.39). RNA interference revealed that a MECOM knockdown suppresses osteoclastogenesis.
Our findings provide new insights into the genetic architecture underlying OF in East Asians.
PMCID: PMC4169276  PMID: 23349225
14.  Soyasaponins Can Blunt Inflammation by Inhibiting the Reactive Oxygen Species-Mediated Activation of PI3K/Akt/NF-kB Pathway 
PLoS ONE  2014;9(9):e107655.
We and others have recently shown that soyasaponins abundant in soybeans can decrease inflammation by suppressing the nuclear factor kappa B (NF-kB)-mediated inflammation. However, the exact molecular mechanisms by which soyasaponins inhibit the NF-kB pathway have not been established. In this study in macrophages, soyasaponins (A1, A2 and I) inhibited the lipopolysaccharide (LPS)-induced release of inflammatory marker prostaglandin E2 (PGE2) to a similar extent as the NF-kB inhibitor (BAY117082). Soyasaponins (A1, A2 and I) also suppressed the LPS-induced expression of cyclooxygenase 2 (COX-2), another inflammatory marker, in a dose-dependent manner by inhibiting NF-kB activation. In defining the associated mechanisms, we found that soyasaponins (A1, A2 and I) blunted the LPS-induced IKKα/β phosphorylation, IkB phosphorylation and degradation, and NF-kB p65 phosphorylation and nuclear translocation. In studying the upstream targets of soyasaponins on the NF-kB pathway, we found that soyasaponins (A1, A2 and I) suppressed the LPS-induced activation of PI3K/Akt similarly as the PI3K inhibitor LY294002, which alone blocked the LPS-induced activation of NF-kB. Additionally, soyasaponins (A1, A2 and I) reduced the LPS-induced production of reactive oxygen species (ROS) to the same extent as the anti-oxidant N-acetyl-L-cysteine, which alone inhibited the LPS-induced phosphorylation of Akt, IKKα/β, IkBα, and p65, transactivity of NF-kB, PGE2 production, and malondialdehyde production. Finally, our results show that soyasaponins (A1, A2 and I) elevated SOD activity and the GSH/GSSG ratio. Together, these results show that soyasaponins (A1, A2 and I) can blunt inflammation by inhibiting the ROS-mediated activation of the PI3K/Akt/NF-kB pathway.
PMCID: PMC4169425  PMID: 25233217
15.  Classification of Multicolor Fluorescence In Situ Hybridization (M-FISH) Images With Sparse Representation 
There has been a considerable interest in sparse representation and compressive sensing in applied mathematics and signal processing in recent years but with limited success to medical image processing. In this paper we developed a sparse representation-based classification (SRC) algorithm based on L1-norm minimization for classifying chromosomes from multicolor fluorescence in situ hybridization (M-FISH) images. The algorithm has been tested on a comprehensive M-FISH database that we established, demonstrating improved performance in classification. When compared with other pixel-wise M-FISH image classifiers such as fuzzy c-means (FCM) clustering algorithms and adaptive fuzzy c-means (AFCM) clustering algorithms that we proposed earlier the current method gave the lowest classification error. In order to evaluate the performance of different SRC for M-FISH imaging analysis, three different sparse representation methods, namely, Homotopy method, Orthogonal Matching Pursuit (OMP), and Least Angle Regression (LARS), were tested and compared. Results from our statistical analysis have shown that Homotopy based method is significantly better than the other two methods. Our work indicates that sparse representations based classifiers with proper models can outperform many existing classifiers for M-FISH classification including those that we proposed before, which can significantly improve the multicolor imaging system for chromosome analysis in cancer and genetic disease diagnosis.
PMCID: PMC4165853  PMID: 22665392
Chromosome image classification; cytogenetics; Homotopy method; image segmentation; sparse representations
16.  Common Copy Number Variation Detection From Multiple Sequenced Samples 
Common copy number variations (CNVs) [1] are small regions of genomic variations at the same loci across multiple samples, which can be detected with high resolution from next-generation sequencing (NGS) technique. Multiple sequencing data samples are often available from genomic studies; examples include sequences from multiple platforms and sequences from multiple individuals. By integrating complementary information from multiple data samples, detection power can be potentially improved. However, most of current CNV detection methods often process an individual sequence sample, or two samples in an abnormal versus matched normal study; researches on detecting common CNVs across multiple samples have been very limited but are much needed. In this paper, we propose a novel method to detect common CNVs from multiple sequencing samples by exploiting the concurrency of genomic variations in read depth signals derived from multiple NGS data. We use a penalized sparse regression model to fit multiple read depth profiles, based on which common CNV identification is formulated as a change-point detection problem. Finally, we validate the proposed method on both simulation and real data, showing that it can give both higher detection power and better break point estimation over several published CNV detection methods.
PMCID: PMC4165854  PMID: 24557694
Copy number variation (CNV); ℓ-0 norm penalty; model selection; next generation sequencing (NGS); Schur complement; structured sparse modeling; the 1000 genomes project
17.  Identification of Genes for Complex Diseases by Integrating Multiple Types of Genomic Data 
Combining multi-type of genomic data for integrative analyses can take advantage of complementary information and thus can have higher power to identify genes/variables that would otherwise be impossible with individual data analysis. Here we proposed a sparse representation based clustering (SRC) method for integrative data analyses, and applied to the analysis of 376821 SNPs in 200 subjects (100 cases and 100 controls) and expression data for 22283 genes in 80 subjects (40 cases and 40 controls) to identify significant genes for osteoporosis (OP). Comparing our results with previous studies, we identified some genes known related to OP risk, as well as some uncovered novel osteoporosis susceptible genes (‘DICER1’, ‘PTMA’, etc.) that may function importantly in osteoporosis etiology. In addition, the identified genes can lead to higher accuracy for the identification of osteoporosis subjects when compared with the traditional T-test and Fisher-exact test, which further validate the proposed SRC approach for integrative analysis.
PMCID: PMC4164202  PMID: 23367184
18.  Detection of common copy number variation with application to population clustering from next generation sequencing data* 
Copy number variation (CNV) is a structural variation in human genome that has been associated with many complex diseases. In this paper we present a method to detect common copy number variation from next generation sequencing data. First, copy number variations are detected from each individual sample, which is formulated as a total variation penalized least square problem. Second, the common copy number discovery from multiple samples is obtained using source separation techniques such as the non-negative matrix factorization (NMF). Finally, the method is applied to population clustering. The results on real data analysis show that two family trio with different ancestries can be clustered into two ethnic groups based on their common CNVs, demonstrating the potential of the proposed method for application to population genetics.
PMCID: PMC4154475  PMID: 23366124
19.  Smoking and Major Depressive Disorder in Chinese Women 
PLoS ONE  2014;9(9):e106287.
To investigate the risk factors that contribute to smoking in female patients with major depressive disorder (MDD) and the clinical features in depressed smokers.
We examined the smoking status and clinical features in 6120 Han Chinese women with MDD (DSM-IV) between 30 and 60 years of age across China. Logistic regression was used to determine the association between clinical features of MDD and smoking status and between risk factors for MDD and smoking status.
Among the recurrent MDD patients there were 216(3.6%) current smokers, 117 (2.0%) former smokers and 333(5.6%) lifetime smokers. Lifetime smokers had a slightly more severe illness, characterized by more episodes, longer duration, more comorbid illness (panic and phobias), with more DSM-IV A criteria and reported more symptoms of fatigue and suicidal ideation or attempts than never smokers. Some known risk factors for MDD were also differentially represented among smokers compared to non-smokers. Smokers reported more stressful life events, were more likely to report childhood sexual abuse, had higher levels of neuroticism and an increased rate of familial MDD. Only neuroticism was significantly related to nicotine dependence.
Although depressed women smokers experience more severe illness, smoking rates remain low in MDD patients. Family history of MDD and environmental factors contribute to lifetime smoking in Chinese women, consistent with the hypothesis that the association of smoking and depression may be caused by common underlying factors.
PMCID: PMC4152240  PMID: 25180682
20.  Gene-gene interaction between RBMS3 and ZNF516 influences bone mineral density 
Osteoporosis is characterized by low bone mineral density (BMD), a highly heritable trait that is determined, in part, by the actions and interactions of multiple genes. While an increasing number of genes have been identified to have independent effects on BMD, few studies have been performed to identify genes that interact with one another to affect BMD. In this study, we performed gene-gene interaction analyses in selected candidate genes in individuals with extremely high vs. low hip BMD (20% tails of the distributions), in two independent US Caucasian samples. The first sample contained 916 unrelated subjects with extreme hip BMD Z-scores selected from a population composed of 2,286 subjects. The second sample consisted of 400 unrelated subjects with extreme hip BMD Z-scores selected from a population composed of 1,000 subjects. Combining results from these two samples, we found one interacting gene pair (RBMS3 vs. ZNF516) which, even after Bonferroni correction for multiple testing, showed consistently significant effects on hip BMD. RMBS3 harbored two SNPs, rs6549904 and rs7640046, both of which had significant interactions with a SNP, rs4891159, located on ZNF516 (P values: 7.04×10−11 and 1.03×10−10). We further validated these results in two additional samples of Caucasian and African descent. The gene pair, RBMS3 vs. ZNF516, was successfully replicated in the Caucasian sample (P values: 8.07×10−3 and 2.91×10−3). For the African sample, a significant interaction was also detected (P values: 0.031 and 0.043), but the direction of the effect was opposite to that observed in the three Caucasian samples. By providing evidence for genetic interactions underlying BMD, this study further delineated the genetic architecture of osteoporosis.
PMCID: PMC4127986  PMID: 23045156
interaction; association; BMD; osteoporosis
21.  Evaluation and Integration of Genetic Signature for Prediction Risk of Nasopharyngeal Carcinoma in Southern China 
BioMed Research International  2014;2014:434072.
Genetic factors, as well as environmental factors, play a role in development of nasopharyngeal carcinoma (NPC). A number of single nucleotide polymorphisms (SNPs) have been reported to be associated with NPC. To confirm these genetic associations with NPC, two independent case-control studies from Southern China comprising 1166 NPC cases and 2340 controls were conducted. Seven SNPs in ITGA9 at 3p21.3 and 9 SNPs within the 6p21.3 HLA region were genotyped. To explore the potential clinical application of these genetic markers in NPC, we further evaluate the predictive/diagnostic role of significant SNPs by calculating the area under the curve (AUC). Results. The reported associations between ITGA9 variants and NPC were not replicated. Multiple loci of GABBR1, HLA-F, HLA-A, and HCG9 were statistically significant in both cohorts (Pcombined range from 5.96 × 10−17 to 0.02). We show for the first time that these factors influence NPC development independent of environmental risk factors. This study also indicated that the SNP alone cannot serve as a predictive/diagnostic marker for NPC. Integrating the most significant SNP with IgA antibodies status to EBV, which is presently used as screening/diagnostic marker for NPC in Chinese populations, did not improve the AUC estimate for diagnosis of NPC.
PMCID: PMC4142549  PMID: 25180181
22.  Comparison of our self-designed rotary self-locking intramedullary nail and interlocking intramedullary nail in the treatment of long bone fractures 
The purpose of this study is to compare the clinical effects of our self-designed rotary self-locking intramedullary nail (RSIN) and interlocking intramedullary nail (IIN) for long bone fractures.
A retrospective study was performed in 1,704 patients who suffered bone fractures and underwent RSIN or IIN operation in our hospital between March 1999 and March 2013, including 494 with femoral fractures, 572 with humeral fractures, and 638 with tibial fractures. Among them, 634 patients were followed up for more than 1 year. The operative time, intraoperative blood loss, postoperative complications, healing rate, and the excellent and good rate of functional recovery were compared between two groups.
Compared with IIN group, RSIN group exhibited significantly shorter operative time and less intraoperative blood loss no matter for humeral, femoral, or tibial fractures (all p < 0.001). The healing rate in patients with more than 1 year follow-up was significantly higher in RSIN group for femoral and tibial fractures (both p < 0.05). In RSIN group, no nail breakage or loosening occurred, but radial nerve injury and incision infection were respectively observed in one patient with humeral fracture. In IIN group, nail breakage or loosening occurred in 7 patients with femoral fractures and 16 patients with tibial fractures, radial nerve injury was observed in 8 patients with humeral fractures, and incision infection was present in 2 patients with humeral fractures and 1 patient with femoral fracture. The complication rate of IIN group was significantly higher than that of RSIN group (p < 0.05). However, there were no significant differences in the excellent and good rate of shoulder, elbow, knee, and ankle joint functional recovery between RSIN group and IIN group.
RSIN may be a reliable and practical alternative method for the treatment of long bone fractures.
PMCID: PMC4115073  PMID: 25047454
Rotary self-locking intramedullary nail; Interlocking intramedullary nail; Retrospective analysis; Long bone fractures
23.  Replication of 6 Obesity Genes in a Meta-Analysis of Genome-Wide Association Studies from Diverse Ancestries 
PLoS ONE  2014;9(5):e96149.
Obesity is a major public health problem with a significant genetic component. Multiple DNA polymorphisms/genes have been shown to be strongly associated with obesity, typically in populations of European descent. The aim of this study was to verify the extent to which 6 confirmed obesity genes (FTO, CTNNBL1, ADRB2, LEPR, PPARG and UCP2 genes) could be replicated in 8 different samples (n = 11,161) and to explore whether the same genes contribute to obesity-susceptibility in populations of different ancestries (five Caucasian, one Chinese, one African-American and one Hispanic population). GWAS-based data sets with 1000 G imputed variants were tested for association with obesity phenotypes individually in each population, and subsequently combined in a meta-analysis. Multiple variants at the FTO locus showed significant associations with BMI, fat mass (FM) and percentage of body fat (PBF) in meta-analysis. The strongest association was detected at rs7185735 (P-value = 1.01×10−7 for BMI, 1.80×10−6 for FM, and 5.29×10−4 for PBF). Variants at the CTNNBL1, LEPR and PPARG loci demonstrated nominal association with obesity phenotypes (meta-analysis P-values ranging from 1.15×10−3 to 4.94×10−2). There was no evidence of association with variants at ADRB2 and UCP2 genes. When stratified by sex and ethnicity, FTO variants showed sex-specific and ethnic-specific effects on obesity traits. Thus, it is likely that FTO has an important role in the sex- and ethnic-specific risk of obesity. Our data confirmed the role of FTO, CTNNBL1, LEPR and PPARG in obesity predisposition. These findings enhanced our knowledge of genetic associations between these genes and obesity-related phenotypes, and provided further justification for pursuing functional studies of these genes in the pathophysiology of obesity. Sex and ethnic differences in genetic susceptibility across populations of diverse ancestries may contribute to a more targeted prevention and customized treatment of obesity.
PMCID: PMC4039436  PMID: 24879436
24.  Genome-wide approaches for identifying genetic risk factors for osteoporosis 
Genome Medicine  2013;5(5):44.
Osteoporosis, the most common type of bone disease worldwide, is clinically characterized by low bone mineral density (BMD) and increased susceptibility to fracture. Multiple genetic and environmental factors and gene-environment interactions have been implicated in its pathogenesis. Osteoporosis has strong genetic determination, with the heritability of BMD estimated to be as high as 60%. More than 80 genes or genetic variants have been implicated in risk of osteoporosis by hypothesis-free genome-wide studies. However, these genes or genetic variants can only explain a small portion of BMD variation, suggesting that many other genes or genetic variants underlying osteoporosis risk await discovery. Here, we review recent progress in genome-wide studies of osteoporosis and discuss their implications for medicine and the major challenges in the field.
PMCID: PMC3706967  PMID: 23731620
25.  Meta-Analysis of Genome-Wide Scans Provides Evidence for Sex- and Site-Specific Regulation of Bone Mass 
Several genome-wide scans have been performed to detect loci that regulate BMD, but these have yielded inconsistent results, with limited replication of linkage peaks in different studies. In an effort to improve statistical power for detection of these loci, we performed a meta-analysis of genome-wide scans in which spine or hip BMD were studied. Evidence was gained to suggest that several chromosomal loci regulate BMD in a site-specific and sex-specific manner.
BMD is a heritable trait and an important predictor of osteoporotic fracture risk. Several genome-wide scans have been performed in an attempt to detect loci that regulate BMD, but there has been limited replication of linkage peaks between studies. In an attempt to resolve these inconsistencies, we conducted a collaborative meta-analysis of genome-wide linkage scans in which femoral neck BMD (FN-BMD) or lumbar spine BMD (LS-BMD) had been studied.
Materials and Methods
Data were accumulated from nine genome-wide scans involving 11,842 subjects. Data were analyzed separately for LS-BMD and FN-BMD and by sex. For each study, genomic bins of 30 cM were defined and ranked according to the maximum LOD score they contained. While various densitometers were used in different studies, the ranking approach that we used means that the results are not confounded by the fact that different measurement devices were used. Significance for high average rank and heterogeneity was obtained through Monte Carlo testing.
For LS-BMD, the quantitative trait locus (QTL) with greatest significance was on chromosome 1p13.3-q23.3 (p = 0.004), but this exhibited high heterogeneity and the effect was specific for women. Other significant LS-BMD QTLs were on chromosomes 12q24.31-qter, 3p25.3-p22.1, 11p12-q13.3, and 1q32-q42.3, including one on 18p11-q12.3 that had not been detected by individual studies. For FN-BMD, the strongest QTL was on chromosome 9q31.1-q33.3 (p = 0.002). Other significant QTLs were identified on chromosomes 17p12-q21.33, 14q13.1-q24.1, 9q21.32-q31.1, and 5q14.3-q23.2. There was no correlation in average ranks of bins between men and women and the loci that regulated BMD in men and women and at different sites were largely distinct.
This large-scale meta-analysis provided evidence for replication of several QTLs identified in previous studies and also identified a QTL on chromosome 18p11-q12.3, which had not been detected by individual studies. However, despite the large sample size, none of the individual loci identified reached genome-wide significance.
PMCID: PMC4016811  PMID: 17228994
osteoporosis; BMD; linkage; meta-analysis; genome search; genome scan

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