[Show abstract][Hide abstract] ABSTRACT: High blood pressure, which affects more than 1 billion people worldwide , is a major risk factor for myocardial infarction, stroke and chronic kidney disease. Approximately 9 million deaths each year are attributable to high blood pressure, including >50% of deaths from coronary heart disease and stroke 1,2. High blood pressure is more prevalent in people of East Asian and South Asian ancestry and is a major contributor to their increased risk of stroke and coronary heart disease 3,4. Genome-wide association studies (GWAS) have identified over 50 genetic loci influencing blood pressure in predominantly European populations 5–16. A role for epigenetic mechanisms in blood pressure regulation has also been suggested 17–20. We carried out a GWAS in East Asians and South Asians, as well as Europeans, to seek both cosmopolitan and population-specific genetic effects for five blood pressure phenotypes: systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure, mean arterial pressure (MAP) and hypertension (Supplementary Fig. 1) (ref. 5). We then sought DNA coding and gene regulatory mechanisms, including DNA methylation and gene transcription, to help explain the relationships we observed between sequence variation and blood pressure. RESULTS Genome-wide association and replication testing We used genome-wide association data from 99,994 individuals of East Asian (n = 31,516), European (n = 35,352) and South Asian (n = 33,126) ancestry. Characteristics of the participants and information on the genotyping arrays and imputation are summarized in Supplementary Tables 1–3. Phenotype-specific meta-analysis was carried out separately for East Asian, European and South Asian samples, followed by a meta-analysis across the three ancestral population groups. The trans-ancestry genome-wide association results identified 4,077 variants with P < 1 × 10 −4 against any blood pressure phenotype, distributed among 630 genetic loci. At each locus, we identified the sentinel SNP (the SNP with the lowest P value against any phenotype) and carried out combined analysis with phenotype-specific results from the International Consortium on Blood Pressure (ICBP) GWAS (maximum n = 87,205) (refs. 8,9). This analysis identified 19 previously unreported loci where the sentinel SNP had suggestive evidence for association with blood pressure (P < 1 × 10 −7
[Show abstract][Hide abstract] ABSTRACT: Background:
A coronary artery disease (CAD) association study of genetic loci previously identified as being associated with blood pressure (BP) was performed in east Asian populations.
Methods and results:
Nine single nucleotide polymorphisms (SNPs) from 9 candidate loci robustly confirmed to be associated with BP in east Asian people, were genotyped. Genotyping was done in up to 17,785 CAD case-control samples (6,522 cases and 11,263 controls). We then tested the associations with other metabolic traits (n≤17,900) and with type 2 diabetes (931 cases and 1,404 controls), and looked up the datasets in silico in other populations. Significant (adjusted P<0.05) CAD associations were found for 5 BP loci: 3 new CAD associations at FIGN,FGF5 and NPR3, and 2 previously reported ones at ATP2B1 and CNNM2. The strongest CAD association was detected at ATP2B1rs2681472 (P=1.7×10(-8)), in the direction inverted to what is generally recognized for BP in the epidemiological studies.CNNM2rs12413409 showed significant association with CAD (P=8.7×10(-7)) and BMI (P=3.5×10(-8), when meta-analyzed with 75,807 east Asian people). The genetic risk score combining BP-raising alleles at each of the SNPs was positively associated with CAD (P=0.011).
A substantial proportion of genetic variants associated with BP were also associated with the risk of CAD in east Asian people, and there was some counter-evidence for causal inference.
[Show abstract][Hide abstract] ABSTRACT: We carried out a trans-ancestry genome-wide association and replication study of blood pressure phenotypes among up to 320,251 individuals of East Asian, European and South Asian ancestry. We find genetic variants at 12 new loci to be associated with blood pressure (P = 3.9 × 10 −11 to 5.0 × 10 −21). The sentinel blood pressure SNPs are enriched for association with DNA methylation at multiple nearby CpG sites, suggesting that, at some of the loci identified, DNA methylation may lie on the regulatory pathway linking sequence variation to blood pressure. The sentinel SNPs at the 12 new loci point to genes involved in vascular smooth muscle (IGFBP3, KCNK3, PDE3A and PRDM6) and renal (ARHGAP24, OSR1, SLC22A7 and TBX2) function. The new and known genetic variants predict increased left ventricular mass, circulating levels of NT-proBNP, and cardiovascular and all-cause mortality (P = 0.04 to 8.6 × 10 −6). Our results provide new evidence for the role of DNA methylation in blood pressure regulation.
[Show abstract][Hide abstract] ABSTRACT: Aim:
It is challenging to identify causal (or target) genes at individual loci detected using genome-wide association studies (GWAS). In order to follow up GWAS loci, we investigated functional genes at homologous loci identified using human lipid GWAS that responded to a high-fat, high-cholesterol diet (HFD) intervention in an animal model.
The HFD intervention was carried out for four weeks in male rats of the spontaneously hypertensive rat strain. The liver and adipose tissues were subsequently excised for analyses of changes in the gene expression as compared to that observed in rats fed normal rat chow (n=8 per group). From 98 lipid-associated loci reported in previous GWAS, 280 genes with rat orthologs were initially selected as targets for the two-staged analysis involving screening with DNA microarray and validation with quantitative PCR (qPCR). Consequently, genes showing a differential expression due to HFD were examined for changes in the expression induced by atorvastatin, which was independently administered to the rats.
Using the HFD intervention in the rats, seven known (Abca1, Abcg5, Abcg8, Lpl, Nr1h3, Pcsk9 and Pltp) and three novel (Madd, Stac3 and Timd4) genes were identified as potential significant targets, with an additional list of 23 suggestive genes. Among these 33 genes, Stac3, Fads1 and six known genes exhibited nominally significant expression changes following treatment with atorvastatin. Six (of 33) genes overlapped with those previously detected in the expression QTL studies.
Our experimental in vivo approach increases the ability to identify target gene(s), when combined with other functional studies, thus improving understanding of the mechanisms by which GWAS variants act.
Journal of atherosclerosis and thrombosis 11/2014; 22(5). DOI:10.5551/jat.27706 · 2.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background/Objective
The 16q12.2 locus in the first intron of FTO has been robustly associated with body mass index (BMI) and type 2 diabetes in genome-wide association studies (GWAS). To improve the resolution of fine-scale mapping at FTO, we performed a systematic approach consisting of two parts.
The first part is to partition the associated variants into linkage disequilibrium (LD) clusters, followed by conditional and haplotype analyses. The second part is to filter the list of potential causal variants through trans-ethnic comparison.
We first examined the LD relationship between FTO SNPs showing significant association with type 2 diabetes in Japanese GWAS and between those previously reported in European GWAS. We could partition all the assayed or imputed SNPs showing significant association in the target FTO region into 7 LD clusters. Assaying 9 selected SNPs in 4 Asian-descent populations—Japanese, Vietnamese, Sri Lankan and Chinese (n≤26,109 for BMI association and n≤24,079 for type 2 diabetes association), we identified a responsible haplotype tagged by a cluster of SNPs and successfully narrowed the list of potential causal variants to 25 SNPs, which are the smallest in number among the studies conducted to date for FTO.
Our data support that the power to resolve the causal variants from those in strong LD increases consistently when three distant populations—Europeans, Asians and Africans—are included in the follow-up study. It has to be noted that this fine-mapping approach has the advantage of applicability to the existing GWAS data set in combination with direct genotyping of selected variants.
PLoS ONE 06/2014; 9(6):e101329. DOI:10.1371/journal.pone.0101329 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The reported prevalence of non-alcoholic fatty liver disease (NAFLD) in Asian populations ranges from 5% to 40% . Using stringent ultrasound criteria, we reported that the prevalence of NAFLD in an urban, adult population of Sri Lankans was 32.6% . Familial clustering has suggested that NAFLD is influenced by genetic factors [3,4]. Genome-wide association studies (GWAS) have successfully identified loci associated with susceptibility to NAFLD in populations of European descent, the most consistent being the patatin-like phospholipase domain containing 3 (PNPLA3) gene rs738409 polymorphism . However, no large-scale genetic studies have been reported in South Asian populations. This article is protected by copyright. All rights reserved.
Liver international: official journal of the International Association for the Study of the Liver 06/2014; 35(2). DOI:10.1111/liv.12624 · 4.85 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recent genetic association studies have identified 55 genetic loci associated with obesity or body mass index (BMI). The vast
majority, 51 loci, however, were identified in European-ancestry populations. We conducted a meta-analysis of associations
between BMI and ∼2.5 million genotyped or imputed single nucleotide polymorphisms among 86 757 individuals of Asian ancestry,
followed by in silico and de novo replication among 7488–47 352 additional Asian-ancestry individuals. We identified four novel BMI-associated loci near the
KCNQ1 (rs2237892, P = 9.29 × 10−13), ALDH2/MYL2 (rs671, P = 3.40 × 10−11; rs12229654, P = 4.56 × 10−9), ITIH4 (rs2535633, P = 1.77 × 10−10) and NT5C2 (rs11191580, P = 3.83 × 10−8) genes. The association of BMI with rs2237892, rs671 and rs12229654 was significantly stronger among men than among women.
Of the 51 BMI-associated loci initially identified in European-ancestry populations, we confirmed eight loci at the genome-wide
significance level (P < 5.0 × 10−8) and an additional 14 at P < 1.0 × 10−3 with the same direction of effect as reported previously. Findings from this analysis expand our knowledge of the genetic
basis of obesity.
Human Molecular Genetics 05/2014; 23(20). DOI:10.1093/hmg/ddu248 · 6.39 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Aim:
Using general Japanese populations, we performed a replication study of genetic loci previously identified in European-descent populations as being associated with uric acid and gout. The relative contribution of non-genetic and genetic factors to the variances in serum uric acid concentration was then evaluated.
Seven single nucleotide polymorphisms (SNPs) were genotyped from 7 candidate loci robustly confirmed in Europeans. Genotyping was performed in up to 17,226 individuals, from which 237 hyperuricemia cases and 3,218 controls were chosen for a case-control study. For 6 SNPs showing a replication of uric acid association in 17,076 general population samples, we further tested the associations with other metabolic traits (n≤5,745) and with type 2 diabetes (931 cases and 1404 controls) and coronary artery disease (806 cases and 1337 controls).
Significant uric acid associations (one-tailed p<0.05) were replicated for 6 loci in Japanese. The strongest association was detected at SLC22A12 rs505802 for uric acid (p=2.4×10(-50)) and ABCG2 rs2231142 for hyperuricemia (p3.6×10(-10)). The combined genetic effect could explain some proportion of inter-individual variation in uric acid (R(2)=0.03) and was more or less comparable to the effect of well-recognized risk factors -BMI (R(2)=0.04) and alcohol intake (R(2)=0.01). The tested SNPs were not significantly associated with cardiovascular risk traits except for GCKR rs780094.
Our results confirm that 6 common uric acid variant loci are reproducible in Japanese. Further investigation is warranted to efficiently use the knowledge about genetic factors in combination with modifiable risk factors when we decide an individual's treatment strategy for hyperuricemia.
Journal of atherosclerosis and thrombosis 12/2012; 20(4). DOI:10.5551/jat.15727 · 2.73 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background/Objective
The CDKAL1 gene is among the best-replicated susceptibility loci for type 2 diabetes, originally identified by genome-wide association studies in humans. To clarify a physiological importance of CDKAL1, we examined effects of a global Cdkal1-null mutation in mice and also evaluated the influence of a CDKAL1 risk allele on body mass index (BMI) in Japanese subjects.
In Cdkal1-deficient (Cdkal1−/−) mice, we performed oral glucose tolerance test, insulin tolerance test, and perfusion experiments with and without high-fat feeding. Based on the findings in mice, we tested genetic association of CDKAL1 variants with BMI, as a measure of adiposity, and type 2 diabetes in Japanese.
On a standard diet, Cdkal1−/− mice were modestly lighter in weight than wild-type littermates without major alterations in glucose metabolism. On a high fat diet, Cdkal1−/− mice showed significant reduction in fat accumulation (17% reduction in %intraabdominal fat, P = 0.023 vs. wild-type littermates) with less impaired insulin sensitivity at an early stage. High fat feeding did not potentiate insulin secretion in Cdkal1−/− mice (1.0-fold), contrary to the results in wild-type littermates (1.6-fold, P<0.01). Inversely, at a later stage, Cdkal1−/− mice showed more prominent impairment of insulin sensitivity and glucose tolerance. mRNA expression analysis indicated that Scd1 might function as a critical mediator of the altered metabolism in Cdkal1−/− mice. In accordance with the findings in mice, a nominally significant (P<0.05) association between CDKAL1 rs4712523 and BMI was replicated in 2 Japanese general populations comprising 5,695 and 12,569 samples; the risk allele for type 2 diabetes was also associated with decreased BMI.
Cdkal1 gene deletion is accompanied by modestly impaired insulin secretion and longitudinal fluctuations in insulin sensitivity during high-fat feeding in mice. CDKAL1 may affect such compensatory mechanisms regulating glucose homeostasis through interaction with diet.
PLoS ONE 11/2012; 7(11):e49055. DOI:10.1371/journal.pone.0049055 · 3.23 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: An intracranial aneurysm (IA), which results in a subarachnoid hemorrhage with a high mortality on rupture, is a major public health concern. To identify genetic susceptibility loci for IA, we carried out a multistage association study using genome-wide single nucleotide polymorphisms (SNPs) in Japanese case-control subjects. In this study, we assessed evidence for association in standard approaches, and additional tests with adjusting sex effects that act between genetic effect and disease. Consequently, five SNPs (P=1.31 × 10(-5) for rs1930095 of intergenic region; P=1.32 × 10(-5) for rs4628172 of TMEM195; P=2.78 × 10(-5) for rs7781293 of TMEM195; P=4.93 × 10(-5) for rs7550260 of ARHGEF11; and P=3.63 × 10(-5) for rs9864101 of IQSEC1) with probabilities of being false positives <0.5 were associated with IA in Japanese population, and the susceptibility genes could have a role in actin remodeling in the ELN/LIMK pathway. This study indicates the presence of several susceptibility loci that deserve further investigation in the Japanese population.
Journal of Human Genetics 10/2010; 55(10):656-61. DOI:10.1038/jhg.2010.82 · 2.46 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recently, a genome-wide association study identified associations between single nucleotide polymorphisms on chromosome 9p21 and risk of harboring intracranial aneurysm (IA). Aneurysm characteristics or subphenotypes of IAs, such as history of subarachnoid hemorrhage, presence of multiple IAs and location of IAs, are clinically important. We investigated whether the association between 9p21 variation and risk of IA varied among these subphenotypes.
We conducted a case-control study of 981 cases and 699 controls in Japanese. Four single nucleotide polymorphisms tagging the 9p21 risk locus were genotyped. The OR and 95% CI were estimated using logistic regression analyses.
Among the 4 single nucleotide polymorphisms, rs1333040 showed the strongest evidence of association with IA (P=1.5x10(-6); per allele OR, 1.43; 95% CI, 1.24-1.66). None of the patient characteristics (gender, age, smoking, and hypertension) was a significant confounder or effect modifier of the association. Subgroup analyses of IA subphenotypes showed that among the most common sites of IAs, the association was strongest for IAs of the posterior communicating artery (OR, 1.69; 95% CI, 1.26-2.26) and not significant for IAs in the anterior communicating artery (OR, 1.22; 95% CI, 0.96-1.57). When dichotomizing IA sites, the association was stronger for IAs of the posterior circulation-posterior communicating artery group (OR, 1.73; 95% CI, 1.32-2.26) vs the anterior circulation group (OR, 1.28; 95% CI, 1.07-1.53). Heterogeneity in these ORs was significant (P=0.032). The associations did not vary when stratifying by history of subarachnoid hemorrhage (OR, 1.42; 95% CI, 1.18-1.71 for ruptured IA; OR, 1.27; 95% CI, 1.00-1.62 for unruptured IA) or by multiplicity of IA (OR, 1.57; 95% CI, 1.21-2.03 for multiple IAs; OR, 1.36; 95% CI, 1.15-1.61 for single IA).
Our results suggest that genetic influence on formation may vary between IA subphenotypes.
[Show abstract][Hide abstract] ABSTRACT: Single nucleotide polymorphisms (SNPs) present in probe-target sequences (SPTS) have been shown to be associated with abnormal genoplot images. We explored the effects of SPTS positions on genoplot images using a data set from a genome-wide association study typed on an Illumina Human Hap300 platform. We screened the physical genomic positions of 308,330 autosomal probes to identify SPTS candidates deposited in dbSNP. The genoplot images across 293 individuals were inspected further in SNPs bearing an SPTS candidate. We identified 35,185 SNPs bearing a single SPTS candidate, including 264 SNPs showing abnormal genoplot images. The frequencies of SPTS at distances within 10 bases from the target SNP were significantly higher in the 264 SNPs showing abnormal genoplot images, than in the remaining 34,921 SNPs (49.62 vs 12.87%; Fisher exact test; P = 2.2 x 10(-16)). Of these 264 SNPs, we randomly selected 20 SNPs and resequenced them in 97 individuals. An SPTS within 10 bases of the target SNP was confirmed in all 20 SNPs, except for one SNP with a small deletion (7 bases) in the probe-target sequence. Taken together, these results suggest an association of a proximal SPTS with an abnormal genoplot image, which could result in spurious genotype detections, highlighting the importance of minimizing systematic errors in microarray experiments.