Non-replication study of a genome-wide association study for hypertension and blood pressure in African Americans

• Main Authors: Kidambi Srividya, Ghosh Soumitra, Kotchen Jane M, Grim Clarence E, Krishnaswami Shanthi, Kaldunski Mary L, Cowley Allen W, Patel Shailendra B, Kotchen Theodore A
• Format: Article
• Language: English
• Published: BMC 2012-04-01
• Series: BMC Medical Genetics
• Online Access: http://www.biomedcentral.com/1471-2350/13/27

<p>Abstract</p> <p>Background</p> <p>A recent genome wide association study in 1017 African Americans identified several single nucleotide polymorphisms that reached genome-wide significance for systolic blood pressure. We attempted to replicate these findings in an independent sample of 2474 unrelated African Americans in the Milwaukee metropolitan area; 53% were women and 47% were hypertensives.</p> <p>Methods</p> <p>We evaluated sixteen top associated SNPs from the above genome wide association study for hypertension as a binary trait or blood pressure as a continuous trait. In addition, we evaluated eight single nucleotide polymorphisms located in two genes (<it>STK-39 and CDH-13</it>) found to be associated with systolic and diastolic blood pressures by other genome wide association studies in European and Amish populations. TaqMan MGB-based chemistry with fluorescent probes was used for genotyping. We had an adequate sample size (80% power) to detect an effect size of 1.2-2.0 for all the single nucleotide polymorphisms for hypertension as a binary trait, and 1% variance in blood pressure as a continuous trait. Quantitative trait analyses were performed both by excluding and also by including subjects on anti-hypertensive therapy (after adjustments were made for anti-hypertensive medications).</p> <p>Results</p> <p>For all 24 SNPs, no statistically significant differences were noted in the minor allele frequencies between cases and controls. One SNP (rs2146204) showed borderline association (p = 0.006) with hypertension status using recessive model and systolic blood pressure (p = 0.02), but was not significant after adjusting for multiple comparisons. In quantitative trait analyses, among normotensives only, rs12748299 was associated with SBP (p = 0.002). In addition, several nominally significant associations were noted with SBP and DBP among normotensives but none were statistically significant.</p> <p>Conclusions</p> <p>This study highlights the importance of replication to confirm the validity of genome wide association study results.</p>