Genetic variation in NEDD4L, an epithelial sodium channel regulator, is associated with cardiovascular disease and cardiovascular death.

OBJECTIVES: We have previously shown that genetic variance in NEDD4L, a regulating protein of a sodium channel in the distal nephron, has been associated with marginally higher blood pressure and enhanced salt sensitivity. Here, we tested if the genetic NEDD4L variation previously associated with salt sensitivity is related to population blood pressure, incidence of cardiovascular disease (CVD) and mortality. METHOD: We genotyped the rs4149601 A→G and rs2288774 T→C NEDD4L variants in 27,564 participants of the Malmö Diet and Cancer Study. The genotype combination previously shown to be associated with salt sensitivity (rs4149601 GG+rs2288774 CC), which was present in 9.6% of participants, was related to cross sectional blood pressure as well as to CVD incidence and mortality during a median follow-up time of 14 years using Cox regression models. RESULTS: Carriers of the NEDD4L salt sensitivity-associated genotype had (mean ± SEM) higher systolic (142 ± 0.4 vs. 141 ± 0.1 mmHg, P = 0.002) and diastolic (86.0 ± 0.5 vs. 85.6 ± 0.2 mmHg, P = 0.025) blood pressure and multivariate adjusted hazards ratio (95% confidence interval) of CVD 1.13 (1.02-1.25, P = 0.018), coronary events 1.20 (1.06-1.37; P = 0.005) and cardiovascular mortality 1.17 (0.99-1.37; P = 0.055) than noncarriers but there was no significant difference in the incidence of stroke and total mortality. CONCLUSION: The NEDD4L salt sensitivity-associated genotype was associated with higher blood pressure, which may translate into increased risk for CVD morbidity and mortality. Interestingly, there was no association with stroke suggesting that the association is partially blood pressure independent.

A functional variant of the NEDD4L gene is associated with beneficial treatment response with ß-blockers and diuretics in hypertensive patients.

OBJECTIVE: The capability of the protein NEDD4L to reduce renal tubular expression of epithelial Na+ channel (ENaC) is influenced by a functional rs4149601 G→A NEDD4L polymorphism. As diuretics and ß-blockers inhibit renal sodium reabsorption and renin release, respectively, we hypothesized that the ß-blocker or diuretic-induced blood pressure reduction and prevention of cardiovascular disease would be greater in patients with the highest ENaC expression (rs4149601 G-allele), whereas there would be no such genetically mediated differences in treatment efficacy among patients treated with the vasodilator diltiazem. METHODS: We related rs4149601 status to 6-month blood pressure reduction and risk of cardiovascular events in 5152 hypertensive patients (DBP ≥ 100 mmHg) from the Nordic Diltiazem Study (NORDIL) randomized to either ß-blocker and/or diuretic-based treatment or diltiazem-based treatment. RESULTS: In patients on ß-blocker or diuretic monotherapy, carriers of the G-allele had greater SBP reduction (19.5 ± 16.8 vs. 15.0 ± 19.3 mmHg, P < 0.001) and DBP reduction (15.4 ± 8.3vs. 14.1 ± 8.4 mmHg, P = 0.02) and during 4.5 years of follow-up among patients randomized to ß-blockers and/or diuretics, carriers of the G-allele had greater protection from cardiovascular events [relative risk (RR) = 0.52, 95% confidence interval (CI) = 0.36-0.74, P < 0.001] as compared to AA homozygotes. Within the diltiazem group, there was no difference in blood pressure reduction or risk of cardiovascular events according to genotype. CONCLUSION: The functional NEDD4L rs4149601 polymorphism influences the efficacy of ß-blocker and/or diuretic-based antihypertensive treatment both in terms of blood pressure reduction and cardiovascular disease protection, whereas diltiazem-based antihypertensive treatment efficacy is not influenced by this NEDD4L polymorphism.

Genetic variants in serum and glucocortocoid regulated kinase 1, a regulator of the epithelial sodium channel, are associated with ischaemic stroke.

OBJECTIVE: Serum and glucocorticoid regulated kinase 1 (SGK1) expression is increased by aldosterone and is a key regulator of the amiloride-sensitive sodium channel (ENaC) in the distal nephron. We have previously shown that two SNPs in SGK1 (rs1057293 and rs1743966) are associated with blood pressure variation and blood pressure progression in the general population. Therefore, we tested the association of these variants with ischaemic stroke. METHODS: Using logistic regression, we analysed rs1057293 and rs1743966 for association with ischaemic stroke in two independent age-matched and sex-matched case-control groups from the twin cities of Lund (cases n=1837 and controls n=947) and Malmö (cases n=888 and controls n=893) in the Scania region of southern Sweden. RESULTS: In additive models adjusted for hypertension, smoking and diabetes, the major allele (G) of rs1057293 was associated (odds ratio, 95% confidence interval; P value) with ischaemic stroke with similar effect size in both studies; in Lund (1.35, 1.11-1.64; P=0.002) and Malmö (1.30, 1.03-1.65; P=0.027). When the two studies were pooled, the overall association was 1.32, 1.14-1.52; P<0.001. The major allele of rs1743966 (A), which was in linkage disequilibrium with rs1057293, showed a similar trend as rs1057293 G-allele but with slightly weaker effect size and P value. CONCLUSION: In two independent but ethnically similar populations, we observed an association between genetic variants in SGK1 and ischaemic stroke. Interestingly, the association seems to be at least partially independent of blood pressure. This could imply that cerebrovascular ENaC or other SGK1-regulated proteins may be of importance for development of ischaemic stroke.

Polymorphism in NEDD4L is associated with increased salt sensitivity, reduced levels of P-renin and increased levels of Nt-proANP.

OBJECTIVE: Neuronal precursor cell expressed developmentally down-regulated 4-like (NEDD4L) is a regulator of the amiloride-sensitive epithelial sodium channel (ENaC), thus a candidate gene for salt sensitivity. Carriers of an intact NEDD4L C2-domain, encoded by the NEDD4L rs4149601 (G/A) GG genotype, together with the C-allele of the NEDD4L rs2288774 (C/T) polymorphism have previously been shown to have increased blood pressure. Our aim was to test if genetic variation in NEDD4L is associated with increased salt sensitivity. METHODS: 39 normotensive subjects were studied. The difference in 24-hour systolic blood pressure after four weeks on 150 mmol/day NaCl intake and four weeks on 50 mmol/day NaCl was defined as salt sensitivity. The rs4149601 and rs2288774 polymorphisms were genotyped using PCR-based techniques. RESULTS: Carriers of the rs4149601 GG-genotype together with the rs2288774 CC-genotype had significantly higher salt sensitivity (median, IQR) (18.0, 7.5-20.0 mmHg vs 6.0, 0.0-10.0 mmHg, P = 0.007) and lower plasma renin concentration (P-renin) (6.0, 2.0-9.5 mU/L vs 15.0, 9.0-24.0 mU/L, P = 0.005) as compared to non-carriers of these genotypes. In carriers of the rs4149601 GG-genotype together with the rs2288774 CC- or CT-genotype, as compared to non-carriers, salt sensitivity was (8.0, 6.0-18.0 mmHg vs 5.0, 0.0-10.0 mmHg, P = 0.07) and P-renin (9.0, 6.0-16.0 mU/L vs 15.0, 9.0-28.0 mU/L, P = 0.03). CONCLUSION: Genetic NEDD4L variation seems to affect salt sensitivity and P-renin in normotensive subjects, suggesting that genotyping of NEDD4L may be clinically useful in order to identify subjects who benefit from dietary salt restriction in the prevention of hypertension.