Chapman, Arlene B.

Recent experimental and clinical studies suggested that apart from playing an essential role in blood pressure homeostasis, aldosterone is involved in the pathophysiology of cardiovascular and renal diseases by inducing structural changes in the heart, kidney, and vessel wall. The interindividual variation of aldosterone response to antihypertensive treatment is considerable, and is at least partially explained by genetic variation. In this study, we investigated aldosterone response to two antihypertensive drugs—a thiazide diuretic and an angiotensin receptor blocker (ARB). Genetic variations in 50 candidate genes were tested for association with aldosterone response in four independent samples: African American (AA) responders to a diuretic ( n = 289), AA responders to an ARB ( n = 252), European American (EA) responders to a diuretic ( n = 295) and EA responders to an ARB ( n = 300). Linear regression was used to test the association with inclusion of age, sex, and body mass index as covariates. The results indicated the existence of one or more variants in the kininogen gene (KNG) that influence interindividual variation in aldosterone response. The significant association was replicated in three of four studied groups. The single nucleotide polymorphism rs4686799 was associated in AA and EA responders to the diuretic ( P = 0.04 and P = 0.07, respectively), and rs5030062 and rs698078 were significantly associated in EA responders to the diuretic ( P = 0.05 and P = 0.01) and EA responders to the ARB ( P = 0.04 and P = 0.02). Although the clinical implication of KNG gene variation to antihypertensive drug response is yet to be determined, this novel candidate locus provides important new insights into drug response physiology.

Single nucleotide polymorphisms (SNPs) in genes encoding or influencing renal sodium transport systems were investigated as potential predictors of blood pressure (BP) response to a thiazide diuretic. A sample of 585 adults with essential hypertension (30 to 59.9 years of age; 50% blacks; 47% women) were treated with hydrochlorothiazide for 4 weeks (25 mg daily, orally) to determine office BP responses. Ambulatory BP responses were measured in a subset of 228 subjects. After adjustment for ethnicity, sex, age, and waist-to-hip ratio, 3 SNPs in WNK1 (rs2107614, rs2277869, and rs1159744), encoding a lysine-deficient protein kinase that regulates thiazide-sensitive sodium-potassium cotransport, made statistically significant contributions to predicting ambulatory BP responses, accounting for 2% to 4% of variation in systolic and diastolic responses ( P <0.05). SNPs in the β 2 -adrenoceptor (rs2400707) and the epithelial sodium channel γ-subunit (rs5723 and rs5729) were associated with similar magnitude of variation in ambulatory systolic BP response ( P =0.028) or office diastolic BP response ( P <0.05), respectively. However, SNPs evaluated in the furosemide-sensitive sodium-potassium chloride cotransporter, potassium inwardly rectifying channel, chloride channel, thiazide-sensitive sodium chloride cotransporter, epithelial sodium channel β-subunit, and the mineralocorticoid receptor were not associated with significant variation in ambulatory or office BP responses. Polymorphisms in genes regulating renal sodium transport, in particular WNK1 , predict interindividual differences in antihypertensive responses to hydrochlorothiazide.