Synopsis and data synthesis of genetic association studies in hypertension for the adrenergic receptor family genes: the CUMAGAS-HYPERT database

Unraveling the relationships between alpha- and beta-adrenergic modulation and the risk of heart failure

Background

The effects of α and ß adrenergic receptor modulation on the risk of developing heart failure (HF) remains uncertain due to a lack of randomized controlled trials. This study aimed to estimate the effects of α and ß adrenergic receptors modulation on the risk of HF and to provide proof of principle for genetic target validation studies in HF.

Methods

Genetic variants within the cis regions encoding the adrenergic receptors α1A, α2B, ß1, and ß2 associated with blood pressure in a 757,601-participant genome-wide association study (GWAS) were selected as instruments to perform a drug target Mendelian randomization study. Effects of these variants on HF risk were derived from the HERMES GWAS (542,362 controls; 40,805 HF cases).

Results

Lower α1A or ß1 activity was associated with reduced HF risk: odds ratio (OR) 0.83 (95% CI 0.74-0.93, P = 0.001) and 0.95 (95% CI 0.93-0.97, P = 8 × 10-6). Conversely, lower α2B activity was associated with increased HF risk: OR 1.09 (95% CI 1.05-1.12, P = 3 × 10-7). No evidence of an effect of lower ß2 activity on HF risk was found: OR 0.99 (95% CI 0.92-1.07, P = 0.95). Complementary analyses showed that these effects were consistent with those on left ventricular dimensions and acted independently of any potential effect on coronary artery disease.

Conclusions

This study provides genetic evidence that α1A or ß1 receptor inhibition will likely decrease HF risk, while lower α2B activity may increase this risk. Genetic variant analysis can assist with drug development for HF prevention.

Computational resources associating diseases with genotypes, phenotypes and exposures

The causes of a disease and its therapies are not only related to genotypes, but also associated with other factors, including phenotypes, environmental exposures, drugs and chemical molecules. Distinguishing disease-related factors from many neutral factors is critical as well as difficult. Over the past two decades, bioinformaticians have developed many computational resources to integrate the omics data and discover associations among these factors. However, researchers and clinicians are experiencing difficulties in choosing appropriate resources from hundreds of relevant databases and software tools. Here, in order to assist the researchers and clinicians, we systematically review the public computational resources of human diseases related to genotypes, phenotypes, environment factors, drugs and chemical exposures. We briefly describe the development history of these computational resources, followed by the details of the relevant databases and software tools. We finally conclude with a discussion of current challenges and future opportunities as well as prospects on this topic.

α1D-adrenoceptor involves the relaxation effect of farrerol in rat aortic vascular smooth muscle cells

The aim of this study was to investigate the relaxation effect of farrerol on rat aortic vascular smooth muscle cells (VSMCs) and its underlying mechanism. VSMCs were cultured primarily and were used to examine the relaxation effect of farrerol. Cells surface and length were measured by dynamic observation, or by rhodamine-phalloidin labeling and hematoxylin-eosin staining. Cells contractive activity were tested using collagen gel contraction assay. The [Ca²⁺]_in was measured with molecular probe fluo-4-AM. The mRNA and protein expression of regulatory proteins for contraction were measured. In addition, rat aortic VSMCs were transfected with lentivirus-mediated α_1D-adrenoceptor gene-shRNA, then the effect of farrerol were detected by the above experimental methods. The results revealed that 10 μΜ AngⅡ promoted cell contraction, increased [Ca²⁺]_in and enhanced collagen contraction in rat aortic VSMCs. 10 μΜ AngⅡ not only increased expression of myosin light chain kinase (MLCK) and smooth muscle protein 22α (SM22α), but also increased phosphorylation level of myosin light chain (MLC) and myosin phosphatase target subunit 1 (MYPT1). The above effects induced by AngⅡ could be significantly inhibited by farrerol in a concentration dependent manner. When the cells were transfected with lentivirus mediated α_1D-adrenoceptor gene-shRNA, the effects of farrerol on changes induced by AngⅡ in rat aortic VSMCs were markedly reversed. In conclusion, farrerol could produce relaxtion effect in rat aortic VSMCs precontracted by 10 μΜ AngⅡ, which was involved in downregulation expression of MLCK and SM22α, and inhibition phosphorylation level of MYPT1 and MLC via activating α_1D-adrenoceptor gene.

mRNA expression profile in peripheral blood mononuclear cells based on ADRB1 Ser49Gly and Arg389Gly polymorphisms in essential hypertension - a case-control pilot investigation in South Indian population

BACKGROUND

β1-Adrenoreceptor (ADRB1) genetic polymorphisms are widely studied for susceptibility to many cardiovascular diseases such as essential hypertension. However, the mRNA expression of ADRB1 is rarely studied.

METHODS

A case-control pilot study with 292 hypertensives and 324 controls was designed to evaluate the role of the Ser49Gly and Arg389Gly, which are commonly studied single nucleotide polymorphisms (SNP), in the mRNA levels of ADRB1, in conjunction with its genetic predisposition to essential hypertension.

RESULTS

Differential expression of ADRB1 mRNA was seen between hypertensives and controls (p<0.01) based on genetic variants of Ser49Gly. Among hypertensive subjects, Ser49Ser and Gly49Gly were highly expressed in comparison to Ser49Gly (p<0.05 and p<0.01, respectively), whereas genetic variants of Arg389Gly did not demonstrate any such variations. We found no association between the ADRB1 SNPs viz., Ser49Gly and Arg389Gly and essential hypertension.

CONCLUSIONS

The increased mRNA levels of Gly49Gly may indicate a plausible role in the interindividual variations in drug response. Further, ADRB1 polymorphisms did not contribute to the genetic risk of essential hypertension. Studies with larger sample size are warranted to confirm these observations in the South Indian population.

ADRB3 Gene Trp64Arg Polymorphism and Essential Hypertension: A Meta-Analysis Including 9,555 Subjects

Background: Presence of the β3-Adrenergic receptor (ADRB3) gene Trp64Arg (T64A) polymorphism may be associated with an increased susceptibility for essential hypertension (EH). A clear consensus, however, has yet to be reached.

Objective and methods: To further elucidate the relationship between the ADRB3 gene Trp64Arg polymorphism and EH, a meta-analysis of 9,555 subjects aggregated from 16 individual studies was performed. The combined odds ratios (ORs) and their corresponding 95% confidence intervals (CI) were evaluated using either a random or fixed effect model.

Results: We found a marginally significant association between ADRB3 gene Trp64Arg polymorphism and EH in the whole population under the additive genetic model (OR: 1.200, 95% CI: 1.00–1.43, P = 0.049). Association within the Chinese subgroup, however, was significant under allelic (OR: 1.150, 95% CI: 1.002–1.320, P = 0.046), dominant (OR: 1.213, 95% CI: 1.005–1.464, P = 0.044), heterozygous (OR: 1.430, 95% CI:1.040–1.970, P = 0.03), and additive genetic models (OR: 1.280, 95% CI: 1.030–1.580, P = 0.02). A significant association was also found in the Caucasian subgroup under allelic (OR: 1.850, 95% CI: 1. 260–2.720, P = 0.002), dominant (OR: 2.004, 95% CI: 1.316–3.052, P = 0.001), heterozygous (OR: 2.220, 95% CI: 1.450–3.400, P = 0.0002), and additive genetic models (OR: 2.000, 95% CI: 1. 330–3.010, P = 0.0009).

Conclusions: The presence of the ADRB3 gene Trp64Arg polymorphism is positively associated with EH, especially in the Chinese and Caucasian population. The Arg allele carriers of ADRB3 gene Trp64Arg polymorphism may be at an increased risk for developing EH.

Germline genetic variants with implications for disease risk and therapeutic outcomes

Genetic testing has multiple clinical applications including disease risk assessment, diagnosis, and pharmacogenomics. Pharmacogenomics can be utilized to predict whether a pharmacologic therapy will be effective or to identify patients at risk for treatment-related toxicity. Although genetic tests are typically ordered for a distinct clinical purpose, the genetic variants that are found may have additional implications for either disease or pharmacology. This review will address multiple examples of germline genetic variants that are informative for both disease and pharmacogenomics. The discussed relationships are diverse. Some of the agents are targeted for the disease-causing genetic variant, while others, although not targeted therapies, have implications for the disease they are used to treat. It is also possible that the disease implications of a genetic variant are unrelated to the pharmacogenomic implications. Some of these examples are considered clinically actionable pharmacogenes, with evidence-based, pharmacologic treatment recommendations, while others are still investigative as areas for additional research. It is important that clinicians are aware of both the disease and pharmacogenomic associations of these germline genetic variants to ensure patients are receiving comprehensive personalized care.

A common hypofunctional genetic variant of GPER is associated with increased blood pressure in women

AIMS

Activation of vascular GPER has been linked to vasodepressor effects in animals. However, the significance of GPER regulation on chronic blood pressure control in humans is unknown.

METHODS

To examine this question we determined the functional significance of expression of a common missense single nucleotide variant of GPER, P16L in vascular smooth muscle cells, and its association with blood pressure in humans. Further, to validate the importance of carrying GPER P16L in the development of hypertension we assessed allele frequency in a cohort of hard-to-treat hypertensive patients referred to a tertiary care clinic.

RESULTS

Expression of the GPER P16L variant (V) vs. wild type (WT) in rat aortic vascular smooth muscle cells, was associated with a significant decrease in G1 (1 μm, a GPER agonist)-mediated ERK phosphorylation (slope of the function of G1-stimulated ERK phosphorylation: GPER content WT: 16.2, 95% CI 9.9, 22.6; V: 5.0, 95% CI 1.0, 9.0; P < 0.005) and apoptosis (slope of the function of G1-stimulated apoptosis: GPER content: WT: 4.4, 95% CI: 3.4, 5.4; V: 2.5, 95% CI 1.6, 2.3 P < 0.005). Normotensive female subjects, but not male subjects, carrying this hypofunctional variant (allele frequency 22%) have increased blood pressure [mean arterial pressure: P16/P16: 80 ± 1 mmHg (n = 204) vs. P16L carriers: 82 ± 1 mmHg (n = 127), 95% CI for difference: 0.6, 4.0 mmHg, P < 0.05], [systolic blood pressure: P16/P16: 105 ± 1 mmHg vs. P16L carriers: 108 ± 1 mmHg, 95% CI for difference:1.0, 5.1 mmHg, P < 0.05], [diastolic blood pressure: P16/P16: 66 ± 0.5 mmHg vs. P16L carriers 68 ± 0.7, 95% CI for difference: 0.2, 3.6 mmHg, P < 0.05]. Further, the P16L allele frequency was almost two-fold higher in female vs. male hypertensive patients (31% vs. 16%, allele ratio 0.5, 95% CI 0.32, 0.76, P < 0.05).

CONCLUSIONS

The common genetic variant, GPER P16L, is hypofunctional and female carriers of this allele have increased blood pressure. There was an increased prevalence in a population of hard-to-treat hypertensive female patients. Cumulatively, these data suggest that in females, impaired GPER function might be associated with increased blood pressure and risk of hypertension.

Genetic association studies of endothelial nitric oxide synthase gene polymorphisms in women with unexplained recurrent pregnancy loss: a systematic and meta-analysis

Recurrent pregnancy loss (RPL) is a multifactorial disorder, both genetic and environmental factors contribute to the development of RPL. Recently, the association between endothelial nitric oxide synthase (eNOS) gene polymorphisms and unexplained recurrent pregnancy loss (URPL) has been reported, and the results were inconsistent. Hence, we performed the meta-analysis to drive a more precise estimation of association between eNOS polymorphisms and URPL. Odds ratio (OR) and its 95% confidence interval were calculated under co-dominant (AA vs. BB, TT vs. GG) and additive (A vs. B, T vs. G) genetic models. Studies of eNOS intron 4 VNTR and Glu298Asp were separated by ethnicities. 13 studies included 1,769 URPL cases and 1,376 healthy controls on eNOS intron 4 VNTR polymorphism, and 11 studies were involved in Glu298Asp polymorphism with 1,498 URPL cases and 1,123 healthy controls. The integrated results showed that eNOS Glu298Asp polymorphism was associated with URPL [ORs were 1.91 (1.42-2.56), P < 0.001; 1.67 (1.36-2.04), P < 0.001, respectively]. When analyses were separated by ethnic subgroups, the association between eNOS Glu298Asp polymorphism and URPL was only observed in East Asians [OR = 1.88 (1.52-2.33), P < 0.001 under additive model], and there was no association between eNOS intron 4 VNTR polymorphism and URPL in Caucasians and East Asians. The results indicated a significant association between eNOS Glu298Asp polymorphism and URPL in East Asians. No association was observed between eNOS intron 4 VNTR polymorphism and URPL in Caucasians and East Asians.

EINVis: a visualization tool for analyzing and exploring genetic interactions in large-scale association studies

Epistasis (gene-gene interaction) detection in large-scale genetic association studies has recently drawn extensive research interests as many complex traits are likely caused by the joint effect of multiple genetic factors. The large number of possible interactions poses both statistical and computational challenges. A variety of approaches have been developed to address the analytical challenges in epistatic interaction detection. These methods usually output the identified genetic interactions and store them in flat file formats. It is highly desirable to develop an effective visualization tool to further investigate the detected interactions and unravel hidden interaction patterns. We have developed EINVis, a novel visualization tool that is specifically designed to analyze and explore genetic interactions. EINVis displays interactions among genetic markers as a network. It utilizes a circular layout (specially, a tree ring view) to simultaneously visualize the hierarchical interactions between single nucleotide polymorphisms (SNPs), genes, and chromosomes, and the network structure formed by these interactions. Using EINVis, the user can distinguish marginal effects from interactions, track interactions involving more than two markers, visualize interactions at different levels, and detect proxy SNPs based on linkage disequilibrium. EINVis is an effective and user-friendly free visualization tool for analyzing and exploring genetic interactions. It is publicly available with detailed documentation and online tutorial on the web at http://filer.case.edu/yxw407/einvis/.

Testing the autonomic nervous system

Autonomic testing is used to define the role of the autonomic nervous system in diverse clinical and research settings. Because most of the autonomic nervous system is inaccessible to direct physiological testing, in the clinical setting the most widely used techniques entail the assessment of an end-organ response to a physiological provocation. The noninvasive measures of cardiovascular parasympathetic function involve the assessment of heart rate variability while the measures of cardiovascular sympathetic function assess the blood pressure response to physiological stimuli. Tilt-table testing, with or without pharmacological provocation, has become an important tool in the assessment of a predisposition to neurally mediated (vasovagal) syncope, the postural tachycardia syndrome, and orthostatic hypotension. Distal, postganglionic, sympathetic cholinergic (sudomotor) function may be evaluated by provoking axon reflex mediated sweating, e.g., the quantitative sudomotor axon reflex (QSART) or the quantitative direct and indirect axon reflex (QDIRT). The thermoregulatory sweat test provides a nonlocalizing measure of global pre- and postganglionic sudomotor function. Frequency domain analyses of heart rate and blood pressure variability, microneurography, and baroreflex assessment are currently research tools but may find a place in the clinical assessment of autonomic function in the future.

The β1-adrenoreceptor gene Arg389Gly and Ser49Gly polymorphisms and hypertension: a meta-analysis

The gene encoding β1-adrenoreceptor is regarded as a hypertension-susceptibility candidate gene. The association of β1-adrenoreceptor gene Arg389Gly and Ser49Gly polymorphisms with hypertension has been exhaustively investigated; however, the studies have yielded inconsistent results. We sought to shed some light on this inconsistency by performing a systemic meta-analysis. Data were extracted from 17 articles (cases/controls: 7,586/8,441) for Arg389Gly, and eight articles (3,582/2,998) for Ser49Gly. The random-effects model was applied irrespective of between-study heterogeneity. Overall results indicated significance for Ser49Gly under both allelic (odds ratio = 1.13; 95 % confidence interval [95 % CI] 1.03-1.26; P = 0.011) and dominant (1.19; 1.04-1.28; 0.011) models, without evidence of heterogeneity (I (2) = 0.0 %). Grouping studies by ethnicity observed marginally significant association for Arg389Gly (0.82; 0.66-1.0; 0.049) and Ser49Gly (1.3; 1.0-1.68; 0.048) polymorphisms in Caucasians under allelic model. Association was strikingly potentiated for both polymorphisms after restricting analyses to studies published in English journals. When only large studies (≥500 subjects) were considered, 389Gly allele decreased the odds of developing hypertension by 16 % (0.84; 0.74-0.95; 0.007). There was no observable publication bias for both polymorphisms. Taken together, our results provide clarification to the logical candidacy of β1-adrenoreceptor gene in the development of hypertension.

Association study between methylenetetrahydrofolate reductase polymorphisms and unexplained recurrent pregnancy loss: a meta-analysis

BACKGROUND

Recurrent pregnancy loss is an important clinical problem. Recently, high-level homocysteine in blood has been considered as a possible cause. Genetic polymorphisms in methylenetetrahydrofolate reductase (MTHFR) have been proved to be the common hereditary factors of high-level homocysteine. The association between MTHFR polymorphisms and unexplained recurrent pregnancy loss (URPL) has been reported but with controversial results. The purpose of present study is to collect and analyze published available data, and evaluate the association between MTHFR polymorphisms and URPL.

METHODS

A meta-analysis was performed to examine the association between MTHFR polymorphisms (C677T and A1298C) and URPL. Odds ratio (OR) and its 95% confidence interval (CI) were used in each study of genotype and allele contrast.

RESULT(S)

MTHFR C677T: The analysis included 3559 URPL cases and 5097 healthy controls. Overall random-effects odds ratios (ORs) were 1.68 (95% CI, 1.32-2.13; P<0.0001) for TT versus total genotypes, 1.35 (95% CI, 1.04-1.76; P=0.0224) for TT and CT genotype combined versus total genotypes and 1.34 (95%CI, 1.13-1.58; P<0.0001) for T versus total alleles. Although significant heterogeneity was found in C677T, it became weaker in the East Asian subgroup and the mixed subgroup when separated by ethnic subgroups. The results showed significant association between MTHFR C677T and URPL in the East Asian subgroup (ORs 2.11 for TT versus total genotype (P=0.0004) and 1.53 for T versus total alleles (P<0.0001)) and in the mixed subgroup (ORs 3.47 for TT versus total genotypes (P<0.0001) and 1.80 for T versus total alleles (P<0.027)), but not in Caucasian subgroup. MTHFR A1298C: The study involved 1163 URPL cases and 1061 healthy controls. Overall random-effects odds ratios (ORs) were 1.37 (95% CI, 0.71-2.67; P=0.3456) for CC versus total genotypes, 1.16 (95%CI, 0.98-1.38; P=0.0833) for CC+AC versus total genotypes and 1.04 (95%CI, 0.84-1.29; P=0.7112) for C versus total alleles. No significant association between MTHFR A1298C polymorphism and URPL was found.

CONCLUSIONS

These results indicate a significant association between MTHFR C677T mutation and URPL in the East Asian subgroup and mixed subgroup, but no significance in MTHFR A1298C mutation.

Between candidate genes and whole genomes: time for alternative approaches in blood pressure genetics

Blood pressure has a significant genetic component, but less than 3% of the observed variance has been attributed to genetic variants identified to date. Candidate gene studies of rare, monogenic hypertensive syndromes have conclusively implicated several genes altering renal sodium balance, and studies of essential hypertension have inconsistently implicated over 50 genes in pathways affecting renal sodium balance and other functions. Genome-wide linkage scans have replicated numerous quantitative trait loci throughout the genome, and over 50 single nucleotide polymorphisms (SNPs) have been replicated in multiple genome-wide association studies. These studies provide considerable evidence that epistasis and other interactions play a role in the genetic architecture of blood pressure regulation, but candidate gene studies have limited scope to test for epistasis, and genome-wide studies have low power for both main effects and interactions. This review summarizes the genetic findings to date for blood pressure, and it proposes focused, pathway-based approaches involving epistasis, gene-environment interactions, and next-generation sequencing to further the genetic dissection of blood pressure and hypertension.

Association of interleukin-6 circulating levels with coronary artery disease: a meta-analysis implementing mendelian randomization approach

BACKGROUND

We aim to investigate whether the association between circulating interleukin 6 (IL-6) levels and the risk for coronary artery disease (CAD) is robust and perhaps even causal by a meta-analysis implementing mendelian randomization approach with IL-6 gene G-174C polymorphism as an instrument.

METHODS

Data were available from 19 articles encompassing 9417 CAD patients and 15982 controls. A random effects model was applied irrespectively of between-study heterogeneity, and publication bias was examined using a funnel plot and the corresponding statistics.

RESULTS

Overall, comparison of IL-6 gene alleles -174C with -174G had 4% increased risk for CAD (95% confidence interval [95% CI]: 0.97-1.10; P=0.285), accompanying marginal heterogeneity (I(2)=38.3%; P=0.033). This association was potentiated in dominant model as odds ratio (OR) reached 1.08 (95% CI: 0.96-1.22; P=0.204) and heterogeneity was significant (I(2)=58.4%; P<0.0005). Subgroup analysis by ethnicity indicated that carriers of -174C allele were associated with a 12% increased risk for CAD in prospective studies involving White populations (OR=1.12; 95% CI: 0.95-1.33; P=0.184), whereas the association in East Asians was remarkably reversed with 37-46% reduced risk. Relative to -174GG homozygotes, carriers of -174C allele had an overall 0.24 pg/ml high circulating IL-6 levels (P=0.047). The predicted OR for 1 pg/ml elevation in IL-6 levels was 1.60 (95% CI: 1.44-1.72; P<0.01) in prospective studies involving White populations. Publication biases were absent for all comparisons (P>0.1).

CONCLUSION

Our findings provided strong evidence on the causal association of circulating IL-6 levels with the development of CAD in White populations.

Alpha-adrenergic receptor gene polymorphisms and cardiovascular reactivity to stress in Black adolescents and young adults

Cardiovascular reactivity to stress and α-adrenergic receptor (α-AR) function may contribute to the development of hypertension. As Black Americans have an increased risk of hypertension, we evaluated associations between α(1A) -AR (Arg492Cys), α(2A) -AR (-1291C/G), and α(2B) -AR (Ins/Del301-303) gene variants and cardiovascular reactivity in 500 normotensive Black youth. Heart rate, preejection period, total peripheral resistance, and blood pressure were measured during cold and psychological stress. The Arg492Cys polymorphism in the α(1A) -AR gene was associated with heart rate reactivity to stress, but the association depended on sex. The -1291C/G promoter polymorphism in the α(2A) -AR gene was associated with vascular reactivity to stress; vasoconstriction increased as a linear function of the number of copies of the variant G allele. Thus, specific associations emerged between genetic variations in α-Ars and cardiovascular reactivity in young Blacks.

Bone mineral density and genetic markers involved in three connected pathways (focal adhesion, actin cytoskeleton regulation and cell cycle): the CUMAGAS-BMD information system

The focal adhesion, the actin cytoskeleton and cell-cycle are connected pathways and their genes are implicated in the pathogenesis of low BMD. Data from 211 studies that investigated the association between BMD and gene variants involved in these pathways were catalogued in a web-based information system and analyzed. In individual studies, significant association was found for 16 variants in lumbar spine, 11 in femoral neck and 5 in hip. In meta-analysis, significant results were shown for the variants COL1A1 rs1800012 (in lumbar spine and femoral neck), COL1A1 rs1107946 (in lumbar spine), TGFB1 rs1982073 (in femoral neck and hip) and TGFB1 rs1800469 (in lumbar spine).

Genome-wide association study identifies six new loci influencing pulse pressure and mean arterial pressure

Numerous genetic loci have been associated with systolic blood pressure (SBP) and diastolic blood pressure (DBP) in Europeans. We now report genome-wide association studies of pulse pressure (PP) and mean arterial pressure (MAP). In discovery (N = 74,064) and follow-up studies (N = 48,607), we identified at genome-wide significance (P = 2.7 × 10(-8) to P = 2.3 × 10(-13)) four new PP loci (at 4q12 near CHIC2, 7q22.3 near PIK3CG, 8q24.12 in NOV and 11q24.3 near ADAMTS8), two new MAP loci (3p21.31 in MAP4 and 10q25.3 near ADRB1) and one locus associated with both of these traits (2q24.3 near FIGN) that has also recently been associated with SBP in east Asians. For three of the new PP loci, the estimated effect for SBP was opposite of that for DBP, in contrast to the majority of common SBP- and DBP-associated variants, which show concordant effects on both traits. These findings suggest new genetic pathways underlying blood pressure variation, some of which may differentially influence SBP and DBP.

Recent findings in the genetics of blood pressure and hypertension traits

We provide an overview of ongoing discovery efforts in the genetics of blood pressure (BP) and hypertension (HTN) traits. Two large genome-wide association meta-analyses of individuals of European descent were recently published, revealing ~13 new loci for BP traits. Only two of these loci harbor genes in a pathway known to affect BP (CYP17A1 and NPPA/NPPB). Functional variants in these loci are still unknown. Few genome-wide association studies (GWAS) of complex diseases have been published from non-European populations. The study of populations with different evolutionary history and linkage disequilibrium (LD) structure, such as individuals of African ancestry, may provide an opportunity to further narrow these regions to identify the causal gene(s). Several collaborative efforts toward discovery of low-frequency variants and copy number variation for BP traits are currently underway. As evidence for new loci for complex diseases accumulates the assessment of the epidemiologic architecture of these variants in populations assumes higher priority. The impact of public health-relevant contexts such as diet, physical activity, psychosocial factors, and aging has not been examined for most common variants associated with BP.

Synopsis and meta-analysis of genetic association studies in osteoporosis for the focal adhesion family genes: the CUMAGAS-OSTEOporosis information system

BACKGROUND

Focal adhesion (FA) family genes have been studied as candidate genes for osteoporosis, but the results of genetic association studies (GASs) are controversial. To clarify these data, a systematic assessment of GASs for FA genes in osteoporosis was conducted.

METHODS

We developed Cumulative Meta-Analysis of GAS-OSTEOporosis (CUMAGAS-OSTEOporosis), a web-based information system that allows the retrieval, analysis and meta-analysis (for allele contrast, recessive, dominant, additive and codominant models) of data from GASs on osteoporosis with the capability of update. GASs were identified by searching the PubMed and HuGE PubLit databases.

RESULTS

Data from 72 studies involving 13 variants of 6 genes were analyzed and catalogued in CUMAGAS-OSTEOporosis. Twenty-two studies produced significant associations with osteoporosis risk under any genetic model. All studies were underpowered (<50%). In four studies, the controls deviated from the Hardy-Weinberg equilibrium. Eight variants were chosen for meta-analysis, and significance was shown for the variants collagen, type I, α1 (COL1A1) G2046T (all genetic models), COL1A1 G-1997T (allele contrast and dominant model) and integrin β-chain β3 (ITGB3) T176C (recessive and additive models). In COL1A1 G2046T, subgroup analysis has shown significant associations for Caucasians, adults, females, males and postmenopausal women. A differential magnitude of effect in large versus small studies (that is, indication of publication bias) was detected for the variant COL1A1 G2046T.

CONCLUSION

There is evidence of an implication of FA family genes in osteoporosis. CUMAGAS-OSTEOporosis could be a useful tool for current genomic epidemiology research in the field of osteoporosis.