Genetic risk factors influence nighttime blood pressure and related cardiovascular complications in patients with coronary heart disease

Total impact of oxidative stress genes on cardiovascular events-a 7-year follow-up study

Cardiovascular (CV) events are the number one cause of lifetime disability and deaths worldwide. It is well known that traditional risk factors do not fully correlate with clinical outcomes; therefore, searching for other markers that would explain CV events' occurrence seems essential. Of importance, one of the main factors at the origin of CV events is oxidative stress, causing inflammation and atherosclerotic plaque instability. Therefore, the present study was conducted to evaluate eight carefully selected genetic polymorphisms related to oxidative stress as risk modifiers for CV events. A cohort of 1020 patients with coronary atherosclerosis was analysed in a 7-year follow-up observational study. The following end points were assessed: CV death, myocardial infarction (MI) and a combined end point of CV death/MI/stroke. Our results show that single polymorphisms are not significant cardiovascular disease risk factors, but genetic risk score (GRS), defined as the accumulation of our eight studied polymorphisms, was significantly associated with the three. Specifically, low GRS was associated with a higher risk of CV death, MI and CV death/MI/stroke. In conclusion, when regarding CV events, GRS investigated here can become clinically meaningful and undoubtedly adds to the knowledge in stratifying the risk of CV events.

Time point of nocturnal trough systolic blood pressure as an independent predictor of cardiovascular events

Nocturnal trough systolic blood pressure (NTSBP) and Time Point of Nocturnal Trough Systolic Blood Pressure (T‐NTSBP) were important parameters of nocturnal blood pressure, the predictive values of which are unclear for stroke outcome. This study aimed to examine the relationship between NTSBP/T‐NTSBP and stroke outcome. The authors used data from a nationwide ambulatory blood pressure monitoring cohort study conducted in China, which recruited 2348 ischemic stroke and transient ischemic attack (TIA) patients. NTSBP was defined as the lowest SBP during nighttime (22:00–6:00), and T‐NTSBP was defined as the corresponding time point of NTSBP. The associations between NTSBP/T‐NTSBP and stroke outcome (stroke recurrence and combined vascular event [CVE]) at 90 days or 1 year were analyzed using cox regression models. According to NTSBP classified by quartile, hazard ratio (HR) with 95% confidence interval (CI) for NTSBP quartile 4 (>129 mm Hg) was 2.727 (1.148–6.478) for CVE at 90‐day, compared with quartile 1 (≤102 mm Hg). However, an attenuated association between NTSBP and CVE was observed at 1 year. In addition, we observed the group of T‐NTSBP at 4:00–6:00 had a lowest CVE incidence at 90 days among four groups (22:00–23:59, 00:00–1:59 2:00–3:59, 4:00–6:00). After multivariable adjustment, T‐NTSBP was significantly associated with CVE incidence at 90 days (T‐NTSBP at the 4:00–6:00 versus the 22:00–23:59 group: HR, 0.433; 95%CI, 0.190–0.986), independent of NTSBP and average nocturnal SBP. Both of NTSBP and T‐NTSBP were important predictors for short‐term cardiovascular risk in ischemic stroke and TIA patients.

ANKS1A genotype predicts cardiovascular events in patients with familial hypercholesterolemia

BACKGROUND

The rs17609940 variant of the ANKS1A gene has been associated with coronary artery disease (CAD) risk in genome-wide association studies (GWAS), but no study has yet replicated this association in familial hypercholesterolemia (FH) population.

OBJECTIVE

The aim of this study is to validate the association between the rs17609940 genotype and incident major adverse cardiovascular events (MACE) in a cohort of genetically-confirmed FH patients.

METHODS

This association study includes 725 genetically-confirmed FH patients with a median observation period of 50 years (33 805 person-years). MACE were defined as either myocardial infarction (MI), stroke, coronary revascularization, hospital admission for unstable angina and cardiovascular disease (CVD) death. The rs17609940 genotype was imputed with an imputation quality of 0.831 following an exome chip genotyping method (Illumina).

RESULTS

The cohort comprised 469 subjects with GG genotype, 218 subjects with CG genotype and 38 subjects with CC genotype. All baseline characteristics were balanced between the three groups. The CC genotype of rs17609940 was associated with a significant lower risk of incident MACE compared to GG and GC carriers in a recessive model (HR 0.30, 95% CI 0.11-0.82, p=0.02). Even after correction for confounding cardiovascular risk factors, the association between the ANKS1A polymorphism and incident MACE remained strongly significant.

CONCLUSIONS

We demonstrated that the rs17609940 SNP of the ANKS1A gene is associated with the risk of incident MACE in FH subjects. The exact mechanism underlying this association remains to be clarified.

Association of Genes Related to Oxidative Stress with the Extent of Coronary Atherosclerosis

Oxidative stress is believed to play a critical role in atherosclerosis initiation and progression. In line with this, in a group of 1099 subjects, we determined eight single nucleotide polymorphisms (SNPs) related to oxidative stress (PON1 c.575A>G, MPO c.−463G>A, SOD2 c.47T>C, GCLM c.−590C>T, NOS3 c.894G>T, NOS3 c.−786T>C, CYBA c.214C>T, and CYBA c.−932A>G) and assessed the extent of atherosclerosis in coronary arteries based on Gensini score. An increased risk of having a Gensini score in the higher half of the distribution was observed for the PON1 c.575G allele (odds ratio (OR) = 1.27, 95% confidence interval (CI): 1.004–1.617, p = 0.046). Next, the genetic risk score (GRS) for the additive effect of the total number of pro-oxidative alleles was assessed. We noted an increase in the risk of having a Gensini score above the median with the maximum number of risk alleles (OR = 2.47, 95% CI: 1.19–5.23, p = 0.014). A univariate Spearman’s test revealed significant correlation between the total number of pro-oxidant alleles (GRS) and the Gensini score (ρ = 0.068, p = 0.03). In conclusion, the PON1 c.575A>G variant and the high number of risk alleles (GRS) were independent risk factors for a high Gensini score. We suggest, however, that GRS might occur as a more valuable component in adding a predictive value to the genetic background of atherosclerosis.

Improved detection of common variants in coronary artery disease and blood pressure using a pleiotropy cFDR method

Plenty of genome-wide association studies (GWASs) have identified numerous single nucleotide polymorphisms (SNPs) for coronary artery disease (CAD) and blood pressure (BP). However, these SNPs only explain a small proportion of the heritability of two traits/diseases. Although high BP is a major risk factor for CAD, the genetic intercommunity between them remain largely unknown. To recognize novel loci associated with CAD and BP, a genetic-pleiotropy-informed conditional false discovery rate (cFDR) method was applied on two summary statistics of CAD and BP from existing GWASs. Stratified Q-Q and fold enrichment plots showed a high pleiotropic enrichment of SNPs associated with two traits. Adopting a cFDR of 0.05 as a threshold, 55 CAD-associated loci (25 variants being novel) and 47 BP loci (18 variants being novel) were identified, 25 of which were pleiotropic loci (13 variants being novel) for both traits. Among the 32 genes these 25 SNPs were annotated to, 20 genes were newly detected compared to previous GWASs. This study showed the cFDR approach could improve gene discovery by incorporating GWAS datasets of two related traits. These findings may provide novel understanding of etiology relationships between CAD and BP.

Longitudinal analysis of sibling correlation on blood pressure using mixed modeling

PURPOSE

Although moderate to high genetic contribution to blood pressure variation have been estimated in numerous studies, the genetic control over the longitudinal change in blood pressure has been less frequently investigated because of the requirement of longitudinal design.

METHODS

Based on blood pressure data from a large-scale family-based longitudinal survey, we introduced hierarchical modeling of longitudinal family data in combination with fractional polynomials for fitting nonlinear age patterns of blood pressure and the mixed-effect models for estimating sibling correlation on blood pressure to assess the genetic and shared environmental effects on blood pressure level as well as on the rate of change in blood pressure over ages.

RESULTS

Significant sibling correlations were estimated on the levels of systolic blood pressure (0.2, 95% CI: 0.10-0.30) and diastolic blood pressure (0.28, 95% CI: 0.18-0.38), whereas for the longitudinal change or the rate of change, significant correlation was estimated only for diastolic blood pressure (0.13, 95% CI: 0.04-0.23). In the sex-specific analysis, similar pattern is observed, but statistical significance was only reached in female siblings with correlation estimates higher than the overall sample.

CONCLUSION

The rate of change in blood pressure is mainly influenced by individual's unique environment; and the genetic and common family environment may play a role in regulating the longitudinal change of diastolic but not systolic blood pressure.