Progress and future aspects in genetics of human hypertension

Deep sequencing of candidate genes identified 14 variants associated with smoking abstinence in an ethnically diverse sample

Despite the large public health toll of smoking, genetic studies of smoking cessation have been limited with few discoveries of risk or protective loci. We investigated common and rare variant associations with success in quitting smoking using a cohort from 8 randomized controlled trials involving 2231 participants and a total of 10,020 common and 24,147 rare variants. We identified 14 novel markers including 6 mapping to genes previously related to psychiatric and substance use disorders, 4 of which were protective (CYP2B6 (rs1175607105), HTR3B (rs1413172952; rs1204720503), rs80210037 on chr15), and 2 of which were associated with reduced cessation (PARP15 (rs2173763), SCL18A2 (rs363222)). The others mapped to areas associated with cancer including FOXP1 (rs1288980) and ZEB1 (rs7349). Network analysis identified significant canonical pathways for the serotonin receptor signaling pathway, nicotine and bupropion metabolism, and several related to tumor suppression. Two novel markers (rs6749438; rs6718083) on chr2 are flanked by genes associated with regulation of bodyweight. The identification of novel loci in this study can provide new targets of pharmacotherapy and inform efforts to develop personalized treatments based on genetic profiles.

Probiotics: functional food ingredients with the potential to reduce hypertension

Hypertension is an increasingly pressing public health concern across the globe. It can be triggered by a variety of factors such as age and diet, as well as the stress of modern life. The traditional treatment of hypertension includes calcium ion blockers, angiotensin II receptor inhibitors and β-receptor blockers, but these drugs have at least some side effects. Recent studies have revealed that intestinal flora plays a vital role in maintaining and promoting human health. This is due to the type and amount of probiotics present in the flora. Probiotics can reduce hypertension symptoms through four mechanisms: regulating vascular oxidative stress, producing short-chain fatty acids, restoring endothelial cell function, and reducing inflammation. It has been reported that certain functional foods, using probiotics as their raw material, can modify the composition of intestinal flora, thus regulating hypertension symptoms. Consequently, utilizing the probiotic function of probiotics in conjunction with the properties of functional foods to treat hypertension is a novel, side-effect-free treatment method. This study seeks to summarize the various factors that contribute to hypertension, the mechanism of probiotics in mitigating hypertension, and the fermented functional foods with probiotic strains, in order to provide a basis for the development of functional foods which utilize probiotics as their raw material and may have the potential to reduce hypertension.

Association between high blood pressure and fitness and fatness in adolescents

Introduction: Excess adiposity is considered the most important risk factor for high blood pressure (HBP) in children and adolescents.Objectives: To explore the association between HBP and overweight (OW) and abdominal obesity (AO), mediated by cardiorespiratory fitness (CRF). To analyze the combined effect of excess adiposity and CRF on HBP among a sample of school-aged children from Montería, Colombia.Materials and methods: Cross-sectional study conducted in a sample of 546 adolescents aged between 11 and 18 years, from 14 randomly selected schools in Montería. Blood pressure, anthropometric, and fitness measures were evaluated by trained personnel using standardized protocols and instrumentation. The association of HBP with fitness and fatness was analyzed using logistic regression models.Results: HBP was associated with OW, AO and low CRF. The inclusion of CRF in this model did not attenuate the association between HBP and OW and between HPB and AO. Adolescents with higher adiposity and low CRF were more likely to have HBP compared with those with lower adiposity and high CRF. Moreover, it was found that excess adiposity and low CRF had an additive effect on the risk of HBP among the sample.Conclusion: HBP is a prevalent condition in children and adolescents from Montería, Colombia. HBP is significantly associated with OW, AO, and low CRF; therefore, it is necessary to implement initiatives to promote healthy habits aimed at this population in order to reduce the incidence rate of HBP in Colombian adolescents.

Mitochondrial outer membrane voltage-dependent anion channel is involved in renal dysfunction in a spontaneously hypertensive rat carrying transfer RNA mutations

Mitochondrial DNA mutations promote hypertensive renal dysfunction, but the molecular mechanism remains unclear. This study compared renal damage between spontaneously hypertensive rats (SHR) and SHR with mitochondrial transfer (t)RNA mutations. To investigate the role of mitochondrial outer membrane voltage-dependent anion channel 1 (VDAC1) in the process of tRNA-promoting mitochondrial dysfunction, we treated HK-2 cells with H₂O₂, cyclosporine (CsA), or atractylodin (Atr) to observe the association between VDAC1 and mitochondrial function. Intriguingly, the mitochondrial structure of SHR carrying tRNA mutations was obviously disordered, and reactive oxygen species production and VDAC1 and Bax expression and binding were increased, which was associated with marked renal dysfunction. The expression of VDAC1 and Bax was also up-regulated in HK-2 cells by H₂O₂ treatment. However, CsA and Atr had no significant effect on the expression of VDAC1 and Bax. H₂O₂ caused mitochondrial membrane potential collapse, while CsA could increase the mitochondrial membrane potential and Atr had the opposite effect. Treatment with H₂O₂ significantly decreased ATP synthesis, which was improved by intervention with Atr. H₂O₂ also decreased the maximum oxygen consumption rate, while CsA and Atr had no significant effect. We found that H₂O₂ promoted the colocalization of VDAC1 and Bax, which was partially inhibited by intervention with CsA or Atr. In conclusion, we found that tRNA mutations promoted hypertensive renal insufficiency. Increased reactive oxygen species was an important associated mechanism, which inhibited mitochondrial function by affecting VDAC1 expression and function.

Contribution of Four Polymorphisms in Renin-Angiotensin-Aldosterone-Related Genes to Hypertension in a Thai Population

Introduction

The roles of genes in the renin-angiotensin-aldosterone system (RAAS) in hypertension, including angiotensin-converting enzyme (ACE), angiotensinogen (AGT), angiotensin II receptor type 1 (AGTR1), and aldosterone synthase (CYP11B2), have been widely studied across different ethnicities, but there has been no such investigation in Thai population.

Materials and Methods

Using 4,150 Thais recorded in the Electricity Generating Authority of Thailand (EGAT) study, we examined the association of rs1799752, rs699, rs5186, and rs1799998 located in or near ACE, AGT, AGTR1, and CYP11B2 genes in hypertension. We investigated their roles in hypertension using multivariate logistic regression and further examined their roles in blood pressure (BP) using quantile regression. Sex, age, and BMI were adjusted as potential confounders.

Results

We did not observe associations between hypertension and rs1799752 (P=0.422), rs699 (P=0.36), rs5186 (P=0.49), and rs1799998 (P=0.71). No evidence of association between these SNPs and BP was found across an entire distribution. A nonlinear relationship between age and BP was observed.

Conclusion

In Thai population, our study showed no evidence of association between RAAS-related genes and hypertension. While our study is the first and largest study to investigate the role of RAAS-related genes in hypertension in Thai population, restricted statistical power due to limited sample size is a limitation.

ATP2B1 rs2681472 and STK39 rs35929607 polymorphisms and risk of Hypertension in Iranian Population

Background: ATP2B1 and STK39 have been introduced as essential hypertension candidate genes. The association of these genes' variations have not been studied in Iranian population yet. Here we aimed to investigate the association of ATP2B1 rs2681472 and STK39 rs35929607 polymorphisms with the risk of hypertension in an Iranian population. Methods: We included 400 individuals in our case-control study: 200 cases with essential hypertension and 200 healthy sex and age matched controls. All subjects were genotyped for rs2681472 and rs35929607 using a PCR-RFLP method. Genotype and allele frequencies were compared between the two groups using chi-squared test. The association was further assessed under log-additive, dominant and recessive genetic models. Results: There was no association between rs2681472 and rs35929607 polymorphisms and risk of essential hypertension in our population (p>0.05). There was also no association between the studied polymorphisms and hypertension under different genetic models. Conclusion: Our study indicated that rs2681472 of ATP2B1 and rs35929607 of STK39 may not have a significant effect on the risk of essential hypertension in Iranian population. More studies are still needed to validate our results.

Heritability and risks associated with early onset hypertension: multigenerational, prospective analysis in the Framingham Heart Study

Objective To determine the role of early onset versus late onset hypertension as a risk factor for hypertension in offspring and cardiovascular death.Design Multigenerational, prospective cohort study.Setting Framingham Heart Study.Participants Two generations of community dwelling participants with blood pressure measurements performed at serial examinations spanning six decades: 3614 first generation participants with mortality data and 1635 initially non-hypertensive second generation participants with data available on parental blood pressure.Main outcome measures The main outcome measures were relation of parental early onset hypertension (age <55 years) with incidence of hypertension in offspring, using regression analyses, and relation of age at hypertension onset with cause specific mortality using a case (cardiovascular death) versus control (non-cardiovascular death) design.Results In second generation participants, having one or both parents with late onset hypertension did not increase the risk of hypertension compared with having parents with no hypertension; by contrast, the hazard ratios of hypertension were 2.0 (95% confidence interval 1.2 to 3.5) and 3.5 (1.9 to 6.1) in participants with one and both parents with early onset hypertension, respectively. In first generation decedents, 1151 cardiovascular deaths occurred (including 630 coronary deaths). The odds of cardiovascular death increased linearly with decreasing age of hypertension onset (P<0.001 for trend). Compared with non-hypertensive participants, hypertension onset at age <45 years conferred an odds ratios of 2.2 (1.8 to 2.7) for cardiovascular death and 2.3 (1.8 to 2.9) for coronary death, whereas hypertension onset at age ≥65 years conferred a lower magnitude odds ratios of 1.5 (1.2 to 1.9) for cardiovascular death and 1.4 (0.98 to 1.9) for coronary death (P≤0.002 for differences in odds ratios between hypertension onset at age <45 and age ≥65).Conclusions Early onset and not late onset hypertension in parents was strongly associated with hypertension in offspring. In turn, early onset compared with late onset hypertension was associated with greater odds of cardiovascular, and particularly coronary, death. These findings suggest it may be important to distinguish between early onset and late onset hypertension as a familial trait when assessing an individual's risk for hypertension, and as a specific type of blood pressure trait when estimating risk for cardiovascular outcomes in adults with established hypertension.

Are genetic polymorphisms in the renin-angiotensin-aldosterone system associated with essential hypertension? Evidence from genome-wide association studies

In candidate gene era, dozens of single-nucleotide polymorphisms (SNPs) within renin-angiotensin-aldosterone system (RAAS) have been reported to be significantly associated with hypertension. However, the unbiased genome-wide association studies (GWAS) rarely identified the SNPs within RAAS were associated with hypertension or blood pressure (BP) traits. In order to figure out whether genetic polymorphisms of RAAS are really associated with hypertension, we systemically searched the GWAS Catalogue and identified all the known RAAS genes and relevant diseases/traits. After data processing, we found that polymorphisms within REN, AGT, ACE2, CYP11B2, ATP6AP2 and HSD11B2 were not associated with any disease or trait. SNPs within ACE, AGTR1, AGTR2, MAS1, RENBP and NR3C2 were associated with other diseases or traits, but showed no direct connection with hypertension. The only SNP associated with a BP trait, systolic BP was rs17367504. However, it is located in the intronic region of MTHFR near many plausible candidate genes, including CLCN6, NPPA, NPPB and AGTRAP. Therefore, the effect of RAAS polymorphisms may have been overestimated during the 'candidate gene era'. In the time of 'precision medicine', the power of RAAS variants needs to be reconsidered when evaluating one's susceptibility of hypertension.

A comprehensive contribution of genes for aryl hydrocarbon receptor signaling pathway to hypertension susceptibility

OBJECTIVE

The present study was designed to investigate whether genetic polymorphisms of the aryl hydrocarbon receptor (AHR) signaling pathway are involved in the molecular basis of essential hypertension (EH).

METHODS

A total of 2160 unrelated Russian individuals comprising 1341 EH patients and 819 healthy controls were recruited into the study. Seven common AHR pathway single-nucleotide polymorphisms (SNPs) such as rs2066853, rs2292596, rs2228099, rs1048943, rs762551, rs1056836, and rs1800566 were genotyped by TaqMan-based allele discrimination assays.

RESULTS

We found that SNP rs2228099 of ARNT is associated with an increased risk of EH (odds ratio=1.20 95% confidence interval: 1.01-1.44, P=0.043) in a dominant genetic model, whereas polymorphism rs762551 of CYP1A2 showed an association with a decreased risk of disease in a recessive genetic model (odds ratio=0.68, 95% confidence interval: 0.52-0.89, P=0.006). A log-likelihood ratio test enabled identification of epistatic interaction effects on EH susceptibility for all SNPs. MB-MDR analysis showed that cigarette smoking, rs1048943, rs762551, rs1056836, and rs2228099 were significant contributing factors in 19, 18, 13, 13, and 11 interaction models, respectively. The best MDR model associated with EH risk included rs1048943, rs762551, rs1056836, and cigarette smoking (cross-validation consistency 100%, prediction error 45.7%, Ppermutation<0.0001). The mRNA expression and in-silico function prediction analyses have confirmed a regulatory potential for a majority of SNPs associated with EH susceptibility.

CONCLUSION

Our pilot study was the first to show that gene-gene and gene-environment interactions in the AHR signaling pathway represent important determinants for the development of EH, and the pathway may become an attractive target for a pharmacological intervention in hypertensive patients in the future.

The Association of Neighborhood Gene-Environment Susceptibility with Cortisol and Blood Pressure in African-American Adults

BACKGROUND

African-American adults are disproportionately affected by stress-related chronic conditions like high blood pressure (BP), and both environmental stress and genetic risk may play a role in its development.

PURPOSE

This study tested whether the dual risk of low neighborhood socioeconomic status (SES) and glucocorticoid genetic sensitivity interacted to predict waking cortisol and BP.

METHODS

Cross-sectional waking cortisol and BP were collected from 208 African-American adults who were participating in a follow-up visit as part of the Positive Action for Today's Health trial. Three single-nucleotide polymorphisms were genotyped, salivary cortisol samples were collected, and neighborhood SES was calculated using 2010 Census data.

RESULTS

The sample was mostly female (65 %), with weight classified as overweight or obese (M BMI = 32.74, SD = 8.88) and a mean age of 55.64 (SD = 15.21). The gene-by-neighborhood SES interaction predicted cortisol (B = 0.235, p = .001, r (2) = .036), but not BP. For adults with high genetic sensitivity, waking cortisol was lower with lower SES but higher with higher SES (B = 0.87). Lower neighborhood SES was also related to higher systolic BP (B = -0.794, p = .028).

CONCLUSIONS

Findings demonstrated an interaction whereby African-American adults with high genetic sensitivity had high levels of waking cortisol with higher neighborhood SES, and low levels with lower neighborhood SES. This moderation effect is consistent with a differential susceptibility gene-environment pattern, rather than a dual-risk pattern. These findings contribute to a growing body of evidence that demonstrates the importance of investigating complex gene-environment relations in order to better understand stress-related health disparities.

Genetic Variation in the Human SORBS1 Gene is Associated With Blood Pressure Regulation and Age at Onset of Hypertension: A SAPPHIRe Cohort Study

Essential hypertension is a complex disease involving multiple genetic and environmental factors. A human gene containing a sorbin homology domain and 3 SH3 domains in the C-terminal region, termed SORBS1, plays a significant role in insulin signaling. We previously found a significant association between the T228A polymorphism and insulin resistance, obesity, and type 2 diabetes. It has been hypothesized that a set of genes responsible for insulin resistance may be closely linked with genes susceptible to the development of hypertension. Identification of insulin resistance-related genetic factors may, therefore, enhance our understanding of essential hypertension. This study aimed to examine whether common SORBS1 genetic variations are associated with blood pressure and age at onset of hypertension in an ethnic Chinese cohort.We genotyped 9 common tagged single nucleotide polymorphisms of the SORBS1 gene in 1136 subjects of Chinese origin from the Stanford Asia-Pacific Program for Hypertension and Insulin Resistance family study. Blood pressure was measured upon enrolment. The associations of the SORBS1 single nucleotide polymorphisms with blood pressure and the presence of hypertension were analyzed with a generalized estimating equation model. We used the false-discovery rate measure Q value with a cutoff <0.1 to adjust for multiple comparisons. In the Cox regression analysis for hypertension-free survival, a robust sandwich variance estimator was used to deal with the within-family correlations with age at onset of hypertension. Gender, body mass index, and antihypertension medication were adjustment covariates in the Cox regression analysis.In this study, genetic variants of rs2281939 and rs2274490 were significantly associated with both systolic and diastolic blood pressure. A genetic variant of rs2274490 was also significantly associated with the presence of hypertension. Furthermore, genetic variants of rs2281939 and rs2274490 were associated with age at onset of hypertension after adjustment for gender, body mass index, and antihypertension medication.In conclusion, we provide evidence for an association between common SORBS1 genetic variations and blood pressure, presence of hypertension, and age at onset of hypertension. The biological mechanism of genetic variation associated with blood pressure regulation needs further investigation.

The sodium leak channel, NALCN, in health and disease

Ion channels are crucial components of cellular excitability and are involved in many neurological diseases. This review focuses on the sodium leak, G protein-coupled receptors (GPCRs)-activated NALCN channel that is predominantly expressed in neurons where it regulates the resting membrane potential and neuronal excitability. NALCN is part of a complex that includes not only GPCRs, but also UNC-79, UNC-80, NLF-1 and src family of Tyrosine kinases (SFKs). There is growing evidence that the NALCN channelosome critically regulates its ion conduction. Both in mammals and invertebrates, animal models revealed an involvement in many processes such as locomotor behaviors, sensitivity to volatile anesthetics, and respiratory rhythms. There is also evidence that alteration in this NALCN channelosome can cause a wide variety of diseases. Indeed, mutations in the NALCN gene were identified in Infantile Neuroaxonal Dystrophy (INAD) patients, as well as in patients with an Autosomal Recessive Syndrome with severe hypotonia, speech impairment, and cognitive delay. Deletions in NALCN gene were also reported in diseases such as 13q syndrome. In addition, genes encoding NALCN, NLF- 1, UNC-79, and UNC-80 proteins may be susceptibility loci for several diseases including bipolar disorder, schizophrenia, Alzheimer's disease, autism, epilepsy, alcoholism, cardiac diseases and cancer. Although the physiological role of the NALCN channelosome is poorly understood, its involvement in human diseases should foster interest for drug development in the near future. Toward this goal, we review here the current knowledge on the NALCN channelosome in physiology and diseases.