Ina Human 50 K cardiovascular chip [19], a customized gene-centric array including ,2100 genes and ,50,000 SNPs genotyped using the Infinium II Assay (Illumina, San Diego, CA). Genotypes were called using GenomeStudio software version 2011.1 and the Genotyping Module version 1.9 calling algorithm (Illumina, San Diego, CA). Participants were excluded if 25033180 sample genotype call rates were below 95 and SNPs were excluded if genotype call rates were below 90 . Sample contamination was detected by checking gender mismatches using X chromosome genotype data and cryptic relatedness was estimated by pairwise identity-bydescent (IBD) analysis implemented using PLINK [20]. After the QC procedures, the total SNP call rate in the remaining individuals was 99.799 . Hardy-Weinberg equilibrium wasStudy protocolEnrolled subjects were randomly assigned at each study site to receive hydrochlorothiazide or atenolol monotherapy; the focus of the metabolomics analyses reported herein is the atenolol monotherapy treatment arm. Atenolol was initiated at 50.0 mg daily for 3 weeks and titrated to 100.0 mg daily on the basis of blood pressure; treatment continued for an additional 6 weeks. Blood pressure was assessed at baseline and after 9 weeks of atenolol treatment by home-recorded blood pressure measurements using a Microlife model 3AC1-PC home BP monitor (BP Microlife, Minneapolis, MN). The device was set to measure BP inEthnic Differences in Exposure to Atenololassessed by chi-square test with one degree of freedom. There were 463 SNPs included in the genetic association analysis.Table 1. Baseline Characteristics of Study Participants According to Race (n = 272).Data AnalysisA Wilcoxon signed rank test was used to detect metabolites that 
were significantly changed by drug treatment. 
The difference in metabolic change between two race groups, Caucasian and African KS 176 site American, was evaluated using a Wilcoxon rank sum test. Q-values [21] were calculated to control for multiple testing false discovery rate (FDR). Correlation matrixes were used to visualize the correlation between metabolites. The modulated modularity clustering algorithm [22] was used to cluster metabolites based on their pairwise Spearman’s correlation coefficients. Pathways and networks were analyzed using multiple approaches. MetaMapp [23] was used to calculate metabolic networks, which were displayed using Cytoscape [24]. Multiple 4EGI-1 site databases were used in the process of data analysis. These included KEGG [25] and PharmGKB [26]. Associations of the 463 SNPs in the lipase genes with oleic acid response to atenolol monotherapy were evaluated using linear regression, adjusting for baseline oleic acid, age, gender and the first 2 principal components for ancestry, which correspond to European and African ancestry, respectively. P values of ,0.0001 (0.05/463) were considered statistically significant. Genetic association analysis was performed using PLINK [20] assuming additive mode 16574785 of inheritance.Characteristics Age, years Men, n ( ) Weight, kg BMI, kg/m2 Caucasians (n = 150) 50.469.5 74 (49.3 ) 88.7617.3 30.565.9 African Americans (n = 122) 46.968.7 31 (25.4 ) 88.2618.1 31.566.5 96.6613.8 113.5614.Waist circumference, cm 97.7612.7 Hip circumference, cm 109.0610.Continuous variables are presented as mean 6 standard deviation; Categorical variables are presented as numbers and percentage. BMI: body mass index. doi:10.1371/journal.pone.0057639.tNetwork ModelingThe process for constructing a model based.Ina Human 50 K cardiovascular chip [19], a customized gene-centric array including ,2100 genes and ,50,000 SNPs genotyped using the Infinium II Assay (Illumina, San Diego, CA). Genotypes were called using GenomeStudio software version 2011.1 and the Genotyping Module version 1.9 calling algorithm (Illumina, San Diego, CA). Participants were excluded if 25033180 sample genotype call rates were below 95 and SNPs were excluded if genotype call rates were below 90 . Sample contamination was detected by checking gender mismatches using X chromosome genotype data and cryptic relatedness was estimated by pairwise identity-bydescent (IBD) analysis implemented using PLINK [20]. After the QC procedures, the total SNP call rate in the remaining individuals was 99.799 . Hardy-Weinberg equilibrium wasStudy protocolEnrolled subjects were randomly assigned at each study site to receive hydrochlorothiazide or atenolol monotherapy; the focus of the metabolomics analyses reported herein is the atenolol monotherapy treatment arm. Atenolol was initiated at 50.0 mg daily for 3 weeks and titrated to 100.0 mg daily on the basis of blood pressure; treatment continued for an additional 6 weeks. Blood pressure was assessed at baseline and after 9 weeks of atenolol treatment by home-recorded blood pressure measurements using a Microlife model 3AC1-PC home BP monitor (BP Microlife, Minneapolis, MN). The device was set to measure BP inEthnic Differences in Exposure to Atenololassessed by chi-square test with one degree of freedom. There were 463 SNPs included in the genetic association analysis.Table 1. Baseline Characteristics of Study Participants According to Race (n = 272).Data AnalysisA Wilcoxon signed rank test was used to detect metabolites that were significantly changed by drug treatment. The difference in metabolic change between two race groups, Caucasian and African American, was evaluated using a Wilcoxon rank sum test. Q-values [21] were calculated to control for multiple testing false discovery rate (FDR). Correlation matrixes were used to visualize the correlation between metabolites. The modulated modularity clustering algorithm [22] was used to cluster metabolites based on their pairwise Spearman’s correlation coefficients. Pathways and networks were analyzed using multiple approaches. MetaMapp [23] was used to calculate metabolic networks, which were displayed using Cytoscape [24]. Multiple databases were used in the process of data analysis. These included KEGG [25] and PharmGKB [26]. Associations of the 463 SNPs in the lipase genes with oleic acid response to atenolol monotherapy were evaluated using linear regression, adjusting for baseline oleic acid, age, gender and the first 2 principal components for ancestry, which correspond to European and African ancestry, respectively. P values of ,0.0001 (0.05/463) were considered statistically significant. Genetic association analysis was performed using PLINK [20] assuming additive mode 16574785 of inheritance.Characteristics Age, years Men, n ( ) Weight, kg BMI, kg/m2 Caucasians (n = 150) 50.469.5 74 (49.3 ) 88.7617.3 30.565.9 African Americans (n = 122) 46.968.7 31 (25.4 ) 88.2618.1 31.566.5 96.6613.8 113.5614.Waist circumference, cm 97.7612.7 Hip circumference, cm 109.0610.Continuous variables are presented as mean 6 standard deviation; Categorical variables are presented as numbers and percentage. BMI: body mass index. doi:10.1371/journal.pone.0057639.tNetwork ModelingThe process for constructing a model based.
