β(1)-adrenergic receptor polymorphisms and response to β-blockade in the African-American study of kidney disease and hypertension (AASK)

Sensitive detection of single-nucleotide polymorphisms by conjugated polymers for personalized treatment of hypertension

Genetic variants among individuals have been associated with ineffective control of hypertension. Previous work has shown that hypertension has a polygenic nature, and interactions between these loci have been associated with variations in drug response. Rapid detection of multiple genetic loci with high sensitivity and specificity is needed for the effective implementation of personalized medicine for the treatment of hypertension. Here, we used a cationic conjugated polymer (CCP)-based multistep fluorescence resonance energy transfer (MS-FRET) technique to qualitatively analyze DNA genotypes associated with hypertension in the Chinese population. Assessment of 10 genetic loci using this technique successfully identified known hypertensive risk alleles in a retrospective study of whole-blood samples from 150 patients hospitalized with hypertension. We then applied our detection method in a prospective clinical trial of 100 patients with essential hypertension and found that personalized treatment of patients with hypertension based on results from the MS-FRET technique could effectively improve blood pressure control rate (94.0% versus 54.0%) and shorten the time duration to controlling blood pressure (4.06 ± 2.10 versus 5.82 ± 1.84 days) as compared with conventional treatment. These results suggest that CCP-based MS-FRET genetic variant detection may assist clinicians in rapid and accurate classification of risk in patients with hypertension and improve treatment outcomes.

Association of the ADRB2 (rs2053044) polymorphism and angiotensin-converting enzyme-inhibitor blood pressure response in the African American Study of Kidney Disease and Hypertension

AIM/OBJECTIVES/BACKGROUND

Hypertension is a risk factor for cardiovascular and kidney disease and is most prevalent in African-American adults. The renin-angiotensin-aldosterone system is integral in blood pressure regulation; angiotensin-converting enzyme inhibitors such as ramipril are first-line treatment options. As decreases in angiotensin result in catecholamine release, β-adrenergic receptor (ADRB) polymorphisms may influence blood pressure response to ramipril.

METHODS

Associations between ADRB polymorphisms and blood pressure response to ramipril were analyzed in the African American Study of Kidney Disease and Hypertension, a randomized clinical trial. A total of 336 participants were included in this analysis. Six polymorphisms were analyzed here: (a) ADRB1 rs1801252 (Ser49Gly) and rs1801253 (Gly389Arg); and (b) ADRB2 rs2053044, rs1042711, rs1042713 (Arg16Gly), and rs1042714 (Gln27Glu). Time to reach a mean arterial pressure (MAP) of 107 mmHg within the first 60 days after randomization was studied using Kaplan-Meier and Cox proportional hazards modeling for univariate and adjusted analyses.

RESULTS

Genotypes at rs2053044, upstream from the ADRB2 5' untranslated region, were associated with time to reach target MAP among those randomized to the usual treatment group. Participants with the GG genotype achieved target MAP on average 12.2 days (38.1%) later than in comparison with those with the A allele (P=0.01). After adjusting for covariates, those with the AA/AG genotype had 2.09 greater odds of reaching MAP of 107 mmHg or less within 60 days of treatment in comparison with those with a GG genotype (hazard ratio=2.09, 95% confidence interval=1.21-3.60).

CONCLUSION

Results suggest that ADRB2 rs2053044 genotypes may be a determinant of blood pressure response to ramipril. Additional studies are needed to clarify the effect of rs2053044 and other 5' untranslated region polymorphisms on gene expression and blood pressure response to angiotensin-converting enzyme inhibitors.

Why do hypertensive patients of African ancestry respond better to calcium blockers and diuretics than to ACE inhibitors and β-adrenergic blockers? A systematic review

BACKGROUND

Clinicians are encouraged to take an individualized approach when treating hypertension in patients of African ancestry, but little is known about why the individual patient may respond well to calcium blockers and diuretics, but generally has an attenuated response to drugs inhibiting the renin-angiotensin system and to β-adrenergic blockers. Therefore, we systematically reviewed the factors associated with the differential drug response of patients of African ancestry to antihypertensive drug therapy.

METHODS

Using the methodology of the systematic reviews narrative synthesis approach, we sought for published or unpublished studies that could explain the differential clinical efficacy of antihypertensive drugs in patients of African ancestry. PUBMED, EMBASE, LILACS, African Index Medicus and the Food and Drug Administration and European Medicines Agency databases were searched without language restriction from their inception through June 2012.

RESULTS

We retrieved 3,763 papers, and included 72 reports that mainly considered the 4 major classes of antihypertensive drugs, calcium blockers, diuretics, drugs that interfere with the renin-angiotensin system and β-adrenergic blockers. Pharmacokinetics, plasma renin and genetic polymorphisms did not well predict the response of patients of African ancestry to antihypertensive drugs. An emerging view that low nitric oxide and high creatine kinase may explain individual responses to antihypertensive drugs unites previous observations, but currently clinical data are very limited.

CONCLUSION

Available data are inconclusive regarding why patients of African ancestry display the typical response to antihypertensive drugs. In lieu of biochemical or pharmacogenomic parameters, self-defined African ancestry seems the best available predictor of individual responses to antihypertensive drugs.

Serum potassium predicts time to blood pressure response among African Americans with hypertensive nephrosclerosis

It is not known whether serum potassium levels affect blood pressure response to anti-hypertensive medication. The African American trial of Kidney disease and Hypertension (AASK) Genomics Study (N=828) is a subset of the AASK trial that randomized 1,094 African American men and women with hypertensive nephrosclerosis to ramipril, amlodipine or metoprolol. Participants were also randomized to a usual (102–107 mmHg) or low (≤92 mmHg) mean arterial pressure (MAP) treatment goal. Time-to-event analyses were used to determine the relationship between serum potassium prior to randomization and time (days) to reach an MAP of 107 mmHg. Mean baseline serum potassium was 4.22 (standard deviation +/− 0.56 and range 2.8–6.0) mmol/L and the median days to reach target MAP was 32 (interquartile range 8–95) days. The adjusted hazard ratio (HR) for each 1mmol/L increase in serum potassium was 1.31 (95%CI: 1.08–1.59) in the usual MAP group, and 1.21 (95%CI: 1.02–1.44) in the low MAP group. Secondary findings suggested that women in the usual MAP group on amlodipine were more likely to reach target MAP compared to women randomized to ramipril (HR: 2.05, 95%CI: 1.30–3.21). Older subjects in the low MAP group (≥55 years) were also more likely to reach target MAP on amlodipine compared to ramipril (HR: 1.57, 95%CI: 1.03–2.38). Serum potassium appears to be a significant predictor of time to blood pressure response, independent of drug class. Results also suggest a benefit of using amlodipine when more rapid blood pressure control is clinically indicated among women and more aggressively managed older subjects.