ORIGINAL ARTICLE Reevaluation of the association of seven candidate genes with blood pressure and hypertension: a replication study and meta-analysis with a larger sample size Fumihiko Takeuchi 1 , Ken Yamamoto 2 , Tomohiro Katsuya 3 , Takao Sugiyama 4 , Toru Nabika 5 , Keizo Ohnaka 6 , Shuhei Yamaguchi 7 , Ryoichi Takayanagi 8 , Toshio Ogihara 9 and Norihiro Kato 1 To obtain evidence for blood pressure (BP) trait association, we conducted an association study of selected candidate gene variants. In Japan, a total of 19 426 individuals underwent testing for genetic associations with systolic BP (SBP)/diastolic BP (DBP) and 9271 individuals (3460 cases and 5811 controls) underwent testing for genetic associations with dichotomous hypertension. Association with seven notable candidate genes was tested, namely, ACE, ADD1, ADRB2, AGT , CYP11B2, GNB3 and NOS3, followed by a joint meta-analysis involving previously reported multi-study populations, including 420 000 individuals (for SBP/DBP) and 417 000 individuals (for hypertension). BP trait associations at two loci (AGT rs699 and CYP11B2 rs1799998) were consistently replicated in the Japanese association study and joint meta-analysis involving the populations described above. Hypertension association reached genome-wide significance for the two variants, specifically, P ¼ 7.3  10 10 for AGT rs699 and P ¼ 3.9  10 8 for CYP11B2 rs1799998. In our study panels, the most significant association was found for CYP11B2 rs1799998 with all three BP traits: P ¼ 1.5  10 5 for SBP, P ¼ 1.8  10 5 for DBP and P ¼ 2.3  10 5 for hypertension. A suggestive association with SBP (P ¼ 0.042), DBP (P ¼ 0.01) and hypertension (P ¼ 1.4  10 5 ) was also detected for ACE rs4340 (a proxy for ACE D/I polymorphism) in the joint meta-analysis. Our data provide evidence for true BP trait associations with two candidate gene variants. These variants were not identified in the previous genome-wide association studies, presumably because they did not reach a given threshold in the discovery stage. Thus, certain variants in genes with clinical and physiological relevance are likely to account for a portion of BP variance in the general population and are worth following up via a target gene approach. Hypertension Research (2012) 35, 825–831; doi:10.1038/hr.2012.43; published online 29 March 2012 Keywords: blood pressure; genes; genetics INTRODUCTION Despite the high heritability estimate (30–50%) of blood pressure (BP) and hypertension, 1–3 to date, associations among candidate genes and these traits have rarely been convincingly demonstrated. With recent technological advances, genome-wide association (GWA) studies, which interrogate a large proportion of the common genetic variants (that is, by genotyping hundreds of thousands of common single-nucleotide polymorphisms (SNPs)) throughout the genome, have allowed the investigation of genetic susceptibility to these traits without a priori hypotheses regarding the underlying pathophysiology. 3 In the first wave of GWA studies, 4–9 few studies appeared to identify loci associated with BP traits at a genome-wide significance level (Po5  10 8 ) when adjusted for multiple testing. In 2009, two large-scale meta-analyses of GWA studies from the Global BP Genetics (Global BPgen) and Cohorts for Heart and Aging Research in Genome Epidemiology (CHARGE) consortia identified a total of 13 independent loci significantly associated with BP. 10,11 Subsequently, meta-analyses of GWA studies in East Asians 12 and in a combined population of Global BPgen and CHARGE 13 further identified a total of 21 additional loci. Most of these associations are in or near genes that had not been suspected of involvement in BP regulation. The sample size of genome-wide exploration in these 1 Department of Gene Diagnostics and Therapeutics, Research Institute, National Center for Global Health and Medicine, Tokyo, Japan; 2 Department of Molecular Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan; 3 Department of Clinical Gene Therapy, Osaka University Graduate School of Medicine, Suita, Japan; 4 Institute for Adult Diseases, Asahi Life Foundation, Tokyo, Japan; 5 Department of Functional Pathology, Shimane University School of Medicine, Izumo, Japan; 6 Department of Geriatric Medicine, Fukuoka, Japan; 7 Department of Internal Medicine III, Shimane University School of Medicine, Izumo, Japan; 8 Department of Medicine and Bioregulatory Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan and 9 Morinomiya University of Medical Sciences, Osaka, Japan Correspondence: Dr N Kato, Department of Gene Diagnostics and Therapeutics, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku- ku, Tokyo 162-8655, Japan. E-mail: nokato@ri.ncgm.go.jp Received 28 December 2011; revised 7 February 2012; accepted 8 February 2012; published online 29 March 2012 Hypertension Research (2012) 35, 825–831 & 2012 The Japanese Society of Hypertension All rights reserved 0916-9636/12 www.nature.com/hr