Genome-wide analysis of blood pressure variability and ischemic stroke

The genetic architecture of blood pressure variability: A genome-wide association study of 9370 participants from UK Biobank

Long-term blood pressure variability (BPV) is a risk factor for cardiovascular diseases, dementia, and stroke. However, its genetic architecture is not fully understood. This study aims to explore its genetic factors and provide more evidence on the mechanisms and further pathological study of BPV. The genome-wide association study (GWAS) is based on the UK Biobank cohort. There were four data collection rounds from 2006 to 2020, and 9370 participants with more than three blood pressure measurements were included. They had a median age of 55 and a male percentage of 50.1%. The phenotypes (BPV) were calculated by four methods and the genetic data contains 6 884 260 single nucleotide polymorphisms (SNPs) after imputation and quality control. A linear regression model was performed with adjustments for sex, age, genotype array, and a significant principal component. Subgroup analysis was performed on hypertension-free participants. The significant and suggestive significant P thresholds were set as 5 × 10-8 and 1 × 10-6 . Six genetic loci (BAD, CCDC88B, GPR137, PLCB3, RPS6KA4 for systolic BPV, and WWC2 for diastolic BPV) were identified by coding region SNPs at the suggestive significant P threshold (1 × 10-6 ). Among them, gene CCDC88B and RPS6KA4 reached the significant P threshold (5 × 10-8 ), with the strongest signal of SNP rs1229536170 (P = 6.36 × 10-8 , β = -.29). The annotation results indicate that genes CCDC88B, GPR137, RPS6KA4, and BAD are associated with long-term SBPV. Their functions of inflammation, epithelial dysfunction, and apoptosis are related to artery stiffness, which was reported as potential mechanisms of BPV.

GWAS of longitudinal trajectories at biobank scale

Biobanks linked to massive, longitudinal electronic health record (EHR) data make numerous new genetic research questions feasible. One among these is the study of biomarker trajectories. For example, high blood pressure measurements over visits strongly predict stroke onset, and consistently high fasting glucose and Hb1Ac levels define diabetes. Recent research reveals that not only the mean level of biomarker trajectories but also their fluctuations, or within-subject (WS) variability, are risk factors for many diseases. Glycemic variation, for instance, is recently considered an important clinical metric in diabetes management. It is crucial to identify the genetic factors that shift the mean or alter the WS variability of a biomarker trajectory. Compared to traditional cross-sectional studies, trajectory analysis utilizes more data points and captures a complete picture of the impact of time-varying factors, including medication history and lifestyle. Currently, there are no efficient tools for genome-wide association studies (GWASs) of biomarker trajectories at the biobank scale, even for just mean effects. We propose TrajGWAS, a linear mixed effect model-based method for testing genetic effects that shift the mean or alter the WS variability of a biomarker trajectory. It is scalable to biobank data with 100,000 to 1,000,000 individuals and many longitudinal measurements and robust to distributional assumptions. Simulation studies corroborate that TrajGWAS controls the type I error rate and is powerful. Analysis of eleven biomarkers measured longitudinally and extracted from UK Biobank primary care data for more than 150,000 participants with 1,800,000 observations reveals loci that significantly alter the mean or WS variability.

Repurposing an anti-cancer agent for the treatment of hypertrophic heart disease

Coronary microvascular dysfunction combined with maladaptive cardiomyocyte morphology and energetics is a major contributor to heart failure advancement. Thus, dually enhancing cardiac angiogenesis and targeting cardiomyocyte function to slow, or reverse, the development of heart failure is a logical step towards improved therapy. We present evidence for the potential to repurpose a former anti-cancer Arg-Gly-Asp (RGD)-mimetic pentapeptide, cilengitide, here used at low doses. Cilengitide targets αvβ3 integrin and this protein is upregulated in human dilated and ischaemic cardiomyopathies. Treatment of mice after abdominal aortic constriction (AAC) surgery with low-dose cilengitide (ldCil) enhances coronary angiogenesis and directly affects cardiomyocyte hypertrophy with an associated reduction in disease severity. At a molecular level, ldCil treatment has a direct effect on cardiac endothelial cell transcriptomic profiles, with a significant enhancement of pro-angiogenic signalling pathways, corroborating the enhanced angiogenic phenotype after ldCil treatment. Moreover, ldCil treatment of Angiotensin II-stimulated AngII-stimulated cardiomyocytes significantly restores transcriptomic profiles similar to those found in normal human heart. The significance of this finding is enhanced by transcriptional similarities between AngII-treated cardiomyocytes and failing human hearts. Taken together, our data provide evidence supporting a possible new strategy for improved heart failure treatment using low-dose RGD-mimetics with relevance to human disease. © 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Variabilities in Childhood Cardiovascular Risk Factors and Incident Diabetes in Adulthood: The Bogalusa Heart Study

OBJECTIVE

Although emerging evidence indicates that increased variability in cardiovascular risk factors (CVRFs) among populations at midlife or later is a reliable predictor of adverse health outcomes, it is unknown whether intraindividual CVRF variability during childhood or adolescence is an independent predictor of later-life diabetes. We aimed to examine the association of CVRF variability during childhood with diabetes in later life.

RESEARCH DESIGN AND METHODS

We included 1,718 participants who participated in the Bogalusa Heart Study and had measures at least four times during childhood (aged 4-19 years). The mean follow-up period was 20.5 years. Intraindividual CVRF variabilities during childhood were calculated using SD, coefficient of variation, deviation from age-predicted values, and residual SD based upon four to eight serial measurements in childhood.

RESULTS

Increased variability in BMI or HDL cholesterol (HDL-C) during childhood, irrespective of the indices used, was significantly positively associated with later-life diabetes risk independent of their respective mean levels in childhood and other possible confounding factors. In combined analysis, the magnitude of the association with diabetes risk was similar for high childhood BMI variability and high childhood HDL-C variability. After adjustments for potential confounding variables, other CVRF variabilities including systolic/diastolic blood pressure, total cholesterol, triglycerides, and LDL cholesterol were not significantly associated with diabetes.

CONCLUSIONS

Increased BMI and HDL-C variabilities during childhood were significant risk factors for the development of diabetes independently of diverse risk factors, which may offer new insights into the childhood origin of adult-onset diabetes.

Generality of genomic findings on blood pressure traits and its usefulness in precision medicine in diverse populations: A systematic review

Remarkable findings from genome-wide association studies (GWAS) on blood pressure (BP) traits have made new insights for developing precision medicine toward more effective screening measures. However, generality of GWAS findings in diverse populations is hampered by some technical limitations. There is no comprehensive study to evaluate source(s) of the non-generality of GWAS results on BP traits, so to fill the gap, this systematic review study was carried out. Using MeSH terms, 1545 records were detected through searching in five databases and 49 relevant full-text articles were included in our review. Overall, 749 unique variants were reported, of those, majority of variants have been detected in Europeans and were associated to systolic and diastolic BP traits. Frequency of genetic variants with same position was low in European and non-European populations (n = 38). However, more than 200 (>25%) single nucleotide polymorphisms were found on same loci or linkage disequilibrium blocks (r² ≥ 80%). Investigating for locus position and linkage disequilibrium of infrequent unique variants showed modest to high reproducibility of findings in Europeans that in some extent was generalizable in other populations. Beyond theoretical limitations, our study addressed other possible sources of non-generality of GWAS findings for BP traits in the same and different origins.

Visit-to-Visit Variability of Blood Pressure Is Associated With Hospitalization and Mortality in an Unselected Adult Population

BACKGROUND

Blood pressure variability (BPV) has been associated with poor health outcomes in high-risk patients, but its association with more general populations is poorly understood.

METHODS

We analyzed outcomes from 240,622 otherwise unselected patients who had 10 or more outpatient blood pressure readings recorded over a 3-year period and were aged from 20 to 100 years.

RESULTS

Whether calculated as SD, average change, or greatest change and systolic or diastolic blood pressure, we found that higher outpatient BPV was associated with subsequent hospitalization and mortality. Systolic pressure average change exceeding 10-12 mm Hg or diastolic exceeding 8 mm Hg significantly increased risk of hospitalization and death (odds ratios [ORs] from 2.0 to 4.5). Variability in the highest decile increased risks even more dramatically, with propensity-matched ORs from 4.4 to 42. A systolic change exceeding 35 mm Hg increased the relative risk of death 4.5-fold. Similarly, a diastolic change greater than 23-24 mm Hg almost tripled the risks of hospitalization and death. Neither stratification for hypertension nor propensity matching for risk factors within the database affected these associations.

CONCLUSIONS

Systolic and diastolic variabilities were each associated with subsequent adverse outcomes. Physicians should pay special attention to patients with swings in blood pressure between clinic visits. Electronic medical records should flag such variability.

Visit-to-visit blood pressure variability and future functional decline in old age

OBJECTIVE

Higher blood pressure variability (BPV), independent of mean blood pressure (BP), has been associated with adverse health outcomes. We investigated the association between visit-to-visit BPV and functional decline in older adults at high cardiovascular risk.

METHODS

In PROspective Study of Pravastatin in the Elderly at Risk, 4745 participants with mean age of 75.2 years and high cardiovascular risk were followed for a mean of 3.2 years. BP was measured in every 3 months during the first 18 months. BPV was defined as the intraindividual SD of measurements across these visits. Functional status in basic and instrumental activities of daily living was measured using the Barthel (ADL) and Lawton (IADL) scales, first at 18 months and then during follow-up until 48 months. Functional decline was calculated over this period.

RESULTS

BPV was not cross-sectionally associated with functional status at 18 months. Higher SBPV was associated with steeper functional decline, whereas DBPV was not. Each 10 mmHg higher SBPV was associated with a 0.064 (95% confidence interval 0.016-0.112, P = 0.009) annual decline in ADL score and with a 0.078 decline (95% confidence interval 0.020-0.136, P = 0.008) in IADL score. These associations were not modified by sex, hypertension or antihypertensives. These findings were independent of mean BP, cardiovascular risk factors and morbidities and cognition.

CONCLUSION

Higher visit-to-visit SBPV but not DBPV was associated with steeper functional decline in older adults at high cardiovascular risk. Higher SBPV is a novel risk factor for functional decline.

Visit-to-Visit Variability of Systolic Blood Pressure and Cardiovascular Disease

Visit-to-visit variability of blood pressure (VVV of BP) is gaining interest as a prognostic marker for stroke, cardiovascular disease, and all-cause mortality. In this review, we discuss different metrics used to define VVV of BP, explore the potential sources of this phenomenon including patient characteristics and antihypertensive medication classes, and discuss recent evidence of its relation with cardiovascular outcomes. Current evidence relies on secondary analyses of clinical trials or on observational studies, none of which was designed to examine VVV of BP specifically. More research is required to develop standardized definitions of VVV of BP, to confirm the value of VVV as a prognostic indicator, and to ascertain whether efforts to reduce VVV of BP in addition to mean BP will improve outcomes.

Genetics of diabetic retinopathy

Diabetic retinopathy (DR) is a polygenic disorder. Twin studies and familial aggregation studies have documented clear familial clustering. Heritability has been estimated to be as high as 27 % for any DR and 52 % for proliferative diabetic retinopathy (PDR), an advanced form of the disease. Linkage analyses, candidate gene association studies and genome-wide association studies (GWAS) performed to date have not identified any widely reproducible risk loci for DR. Combined analysis of the data from multiple GWAS is emerging as an important next step to explain the unaccounted heritability. Key factors to future discovery of the genetic underpinnings of DR are precise DR ascertainment, a focus on the more heritable disease forms such as PDR, stringent selection of control participants with regards to duration of diabetes, and methods that allow combination of existing datasets from different ethnicities to achieve sufficient sample sizes to detect variants with modest effect sizes.