Taishi Sasaoka

Replication of the association between a chromosome 9p21 polymorphism and coronary artery disease in Japanese and Korean populations

AbstractCoronary artery disease (CAD) has become a major health problem in many countries. Recent genome-wide association studies have identified the association between rs1333049 on chromosome 9p21 and susceptibility to CAD in Caucasoid populations. In this study, we evaluated the associations of rs1333049 with CAD in Japanese (604 patients and 1,151 controls) and Koreans (679 patients and 706 controls). We found a significant association in both Japanese [odds ratio (OR) = 1.30, 95% confidence interval (CI); 1.13–1.49, p = 0.00027, allele count model] and Koreans (OR = 1.19, 95% CI; 1.02–1.38, p = 0.025, allele count model). These observations demonstrated that chromosome 9p21 was the susceptibility locus for CAD also in East Asians.

E-Selectin Polymorphism Associated With Myocardial Infarction Causes Enhanced Leukocyte-Endothelial Interactions Under Flow Conditions

Objective—Polymorphisms found in genes encoding adhesion molecules have been reported to be associated with atherosclerosis. We investigated the Ser128Arg polymorphism in the E-selectin gene in Japanese patients with myocardial infarction and its functional significance. Methods and Results—Results from 135 patients with myocardial infarction and 327 control subjects revealed that the frequency of Arg128-positive was significantly higher in the patients than in controls (12.6% versus 6.7%; odds ratio, 2.0; 95% CI, 1.04 to 3.85), indicating that the Ser128Arg polymorphism was associated with myocardial infarction. We then generated a recombinant E-selectin adenovirus carrying a mutation (AdS128R-E) and compared it with its wild-type counterpart by evaluating the adhesion characteristics of transduced human umbilical vein endothelial cells under flow. AdS128R-E–transduced human umbilical vein endothelial cells supported significantly more rolling and adhesion of neutrophils and mononuclear cells compared with human umbilical vein endothelial cells transduced with AdWT-E (P <0.001) and also exhibited significantly greater levels of phosphorylation of extracellular signal regulated kinase 1 and 2 and p38 mitogen-activated protein kinase, suggesting that an altered endothelial signaling pathway is associated with this polymorphism. Conclusions—Our results suggest that the E-selectin Ser128Arg polymorphism can functionally alter leukocyte-endothelial interactions as well as biochemical and biological consequences, which may account for the pathogenesis of myocardial infarction.

Polymorphisms in the platelet-endothelial cell adhesion molecule-1 (PECAM-1) gene, Asn563Ser and Gly670Arg, associated with myocardial infarction in the Japanese.

Abstract: We examined three missense polymorphisms of platelet‐endothelial cell adhesion molecule‐1 (PECAM‐1), Val125Leu, Asn563Ser, and Gly670Arg, in 136 Japanese patients with myocardial infarction and 235 healthy Japanese controls. We found that these polymorphisms were in linkage disequilibrium with each other and that frequencies of 125Leu, 563Ser, and 670Arg alleles were significantly increased in patients compared with controls (0.522 vs 0.447, p= 0.048; 0.585 vs 0.502, p= 0.030; and 0.577 vs 0.492, p= 0.032, respectively). The frequencies of homozygotes for 563Ser and 670Arg alleles were also significantly increased in the patients (33.1% vs 23.4%, odds risk [OR] = 1.62, p= 0.040, 95% confidence interval [95%CI] = 1.01‐2.58; and 32.4% vs 23.0%, OR = 1.60, p= 0.048, 95%CI = 1.00‐2.57, respectively). These observations suggest that the 563Ser/Ser genotype and 670Arg/Arg genotype of PECAM‐1 are novel genetic risk factors of myocardial infarction in Japanese. Stratification analysis of the patients showed that the associations of these PECAM‐1 genotypes with myocardial infarction were preferentially found in male and younger patients (age of onset of myocardial infarction less than 60 years). In addition, the associations were stronger in patients with three‐vessel disease than in the others and appeared independent of conventional risk factors including smoking, hypertension, diabetes mellitus, hyperlipidemia, and obesity.

MICA gene polymorphism in Takayasu's arteritis and Buerger's disease

To further clarify the HLA-linked genes susceptible to arterio-vasculitis of unknown etiology, Takayasus arteritis and Buergers disease, polymorphism in the MICA gene, a newly identified gene near the HLA-B gene and expressed in epithelial cell lineage, was investigated. Polymerase chain reaction (PCR)-DNA conformation polymorphism (DCP) analysis and subsequent sequencing of the MICA gene have revealed that there are 5 MICA alleles which are different in the number of a GCT repeat in exon 5: MICA alleles MICA-1.1, -1.2, -1.3 and -1.4 have 9, 6, 5 and 4 GCT repeats, respectively, and MICA-1.5 has 5 GCT repeats with a 1 bp frameshift insertion in the repeat. MICA genotyping data in 81 Japanese patients with Takayasus arteritis, 38 Japanese patients with Buergers disease, and 160 healthy Japanese controls showed that MICA-1.2 and -1.4 were significantly associated with Takayasus arteritis and Buergers disease, respectively. Because MICA-1.2 and -1.4 were in strong linkage disequilibria with HLA-B52 and -B54 in the Japanese populations, respectively, we have compared the odds ratio (OR) of the risk to the diseases for individuals having both or each of the disease-associated MICA and HLA-B alleles. It was found that MICA-1.2 gave a significantly high OR of risk to Takayasus arteritis in the absence of HLA-B52, suggesting that the HLA-linked gene susceptible to Takayasus arteritis is mapped near the MICA gene. In contrast, MICA-1.4 gave a significantly high OR of risk to Buergers disease only in the presence of HLA-B54, suggesting that the HLA-linked gene susceptible to Buergers disease is linked to the HLA-B54-MICA-1.4 haplotype, and may be differently mapped from that to Takayasus arteritis.

Validation of eight genetic risk factors in East Asian populations replicated the association of BRAP with coronary artery disease.

Coronary artery disease (CAD) is caused by a thrombotic occlusion or spasm of the coronary artery. Association of genetic variants with susceptibility to CAD has been reported in various populations, but the association should be replicated in other populations to establish the role of genetic variants in CAD. We conducted a case–control study with a total of 1480 CAD cases and 2115 controls from two East Asian populations, Japanese and Korean, to validate the associations of CAD with eight single nucleotide polymorphisms (SNPs) in eight loci, which were identified from large-scale whole-genome association studies in Europeans or East Asians. Among the tested SNPs, one SNP in BRAP (rs11066001) showed a significant association in allele frequency distribution with CAD in both the Japanese (Odds ratio (OR)=1.63, 95% confidence interval (CI); 1.41–1.89, P=5.0 × 10−11, corrected P (Pc)=4.0 × 10−10) and Korean populations (OR=1.68, 95% CI; 1.41–2.00, P=6.5 × 10−9, Pc=5.2 × 10−9), and a meta-analysis showed a significant association in the East Asian populations (OR=1.65, 95% CI; 1.48–1.85, P=1.8 × 10−18, Pc=1.4 × 10−17), whereas no evidence of association was found for the other SNPs. In addition, a combined analysis of BRAP and another CAD locus on 9p21 suggested that these loci had a synergistic role in the susceptibility. Failure to replicate the association with the other SNPs, which were reported in the European populations, suggested that their contributions to CAD were not large enough to be readily captured in the East Asian populations.

Replication studies for the association of PSMA6 polymorphism with coronary artery disease in East Asian populations.

Coronary artery disease (CAD) has become a major health problem in many countries because of its increasing prevalence and high mortality. Recently, an association of a functional sequence variation, −8C>G, in the human proteasome subunit α type 6 gene (PSMA6) with the susceptibility to CAD was reported. To validate the association, we investigated a total of 1330 cases and 2554 controls from Japanese and Korean populations for PSMA6 genotypes, and no evidence of the association was obtained in both Japanese (odds ratio (OR)=1.03, 95% confidence interval (CI); 0.90–1.19, P=0.66, allele count model) and Korean populations (OR=1.00, 95% CI; 0.86–1.17, P=0.95, allele count model). However, when a meta-analysis of data from this study and previously reported six replication studies was done, OR was 1.08 for the G allele (95% CI; 1.02–1.14, P=0.0057), suggesting that the contribution of PSMA6 to CAD was not large enough to be readily replicated. Further studies are required to establish the contribution of this variant in the susceptibility to CAD.

Genetic invalidation of Lp-PLA2 as a therapeutic target: large-scale study of five functional Lp-PLA2-lowering alleles

Aims Darapladib, a potent inhibitor of lipoprotein-associated phospholipase A2 (Lp-PLA2), has not reduced risk of cardiovascular disease outcomes in recent randomized trials. We aimed to test whether Lp-PLA2 enzyme activity is causally relevant to coronary heart disease. Methods In 72,657 patients with coronary heart disease and 110,218 controls in 23 epidemiological studies, we genotyped five functional variants: four rare loss-of-function mutations (c.109+2T > C (rs142974898), Arg82His (rs144983904), Val279Phe (rs76863441), Gln287Ter (rs140020965)) and one common modest-impact variant (Val379Ala (rs1051931)) in PLA2G7, the gene encoding Lp-PLA2. We supplemented de-novo genotyping with information on a further 45,823 coronary heart disease patients and 88,680 controls in publicly available databases and other previous studies. We conducted a systematic review of randomized trials to compare effects of darapladib treatment on soluble Lp-PLA2 activity, conventional cardiovascular risk factors, and coronary heart disease risk with corresponding effects of Lp-PLA2-lowering alleles. Results Lp-PLA2 activity was decreased by 64% (p = 2.4 × 10–25) with carriage of any of the four loss-of-function variants, by 45% (p < 10–300) for every allele inherited at Val279Phe, and by 2.7% (p = 1.9 × 10–12) for every allele inherited at Val379Ala. Darapladib 160 mg once-daily reduced Lp-PLA2 activity by 65% (p < 10–300). Causal risk ratios for coronary heart disease per 65% lower Lp-PLA2 activity were: 0.95 (0.88–1.03) with Val279Phe; 0.92 (0.74–1.16) with carriage of any loss-of-function variant; 1.01 (0.68–1.51) with Val379Ala; and 0.95 (0.89–1.02) with darapladib treatment. Conclusions In a large-scale human genetic study, none of a series of Lp-PLA2-lowering alleles was related to coronary heart disease risk, suggesting that Lp-PLA2 is unlikely to be a causal risk factor.

Validation of the association between AGTRL1 polymorphism and coronary artery disease in the Japanese and Korean populations

Coronary artery disease (CAD) and stroke are the major health problems in many countries because of their increasing prevalence and high mortality. It is well known that CAD and stroke are based on atherosclerosis and shared environmental and genetic risk factors. Recently, an association of a functional sequence variation −154G>A in the angiotensin receptor-like 1 (AGTRL1) with a susceptibility to stroke was reported. In this study, we investigated a total of 1479 CAD cases and 2062 controls from the Japanese and Korean populations to validate the association of AGTRL1 with CAD. However, we obtained no evidence of the association in both the Japanese (odds ratio (OR)=0.95, 95% confidence interval (CI); 0.82–1.10, P=0.47, allele count model) and Korean (OR=0.90, 95% CI; 0.77–1.05, P=0.18, allele count model) populations. In addition, there was no trend of association between the risk allele and severity of coronary atherosclerosis. These data suggested that AGTRL1 did not contribute much to the atherosclerosis of the coronary artery.