Familial aggregation and childhood blood pressure

Genetics of Hypertension: From Monogenic Analysis to GETomics

Arterial hypertension is the most frequent cardiovascular risk factor all over the world, and it is one of the leading drivers of the risk of cardiovascular events and death. It is a complex trait influenced by heritable and environmental factors. To date, the World Health Organization estimates that 1.28 billion adults aged 30-79 years worldwide have arterial hypertension (defined by European guidelines as office systolic blood pressure ≥ 140 mmHg or office diastolic blood pressure ≥ 90 mmHg), and 7.1 million die from this disease. The molecular genetic basis of primary arterial hypertension is the subject of intense research and has recently yielded remarkable progress. In this review, we will discuss the genetics of arterial hypertension. Recent studies have identified over 900 independent loci associated with blood pressure regulation across the genome. Comprehending these mechanisms not only could shed light on the pathogenesis of the disease but also hold the potential for assessing the risk of developing arterial hypertension in the future. In addition, these findings may pave the way for novel drug development and personalized therapeutic strategies.

Association of blood pressure and hypertension between parents and offspring: The Korea National Health and Nutrition Examination Survey

As the number of hypertension cases in the pediatric population is growing, we aimed to investigate the parent-offspring association of hypertension in Korea. We performed a cross-sectional analysis using the data of children and adolescents aged 10-18 years and their parents extracted from the Korea National Health and Nutrition Examination Survey (2008-2018). We analyzed the correlation of blood pressure (BP) between offspring and their parents and investigated the odds ratio (OR) of having hypertension in offspring based on parental hypertensive status. A total of 3996 children and adolescents (2224 boys and 1772 girls) aged 10-18 years and their parents (3197 fathers and 3197 mothers) were evaluated. Both boys and girls had positive associations with both parents for systolic and diastolic BP. When neither parent, only the father, only the mother, or both parents were hypertensive, 6.6%, 10.4%, 13.3%, and 25.3% of boys and 6%, 12%, 12.7%, and 22.1% of girls had hypertension, respectively. The risk of having hypertension among offspring was approximately two times higher when one parent was hypertensive and over four times higher when both parents were hypertensive compared to that among controls whose parents were not hypertensive (OR: 2.230, 1.655, and 5.021 in boys with hypertension and 2.321, 2.169, and 4.554 in girls with hypertension in the mother only, the father only, and both parents, respectively). We identified familial aggregation of hypertension in Korea. As there was an increased likelihood of having hypertension in children with parental hypertension, parental hypertension may be utilized as a screening tool for hypertension in children.

Hypertension in Children and Young Adults

Primary hypertension (PH) is most common during adolescence with increasing prevalence globally, alongside the epidemic of obesity. Unlike in adults, there are no data on children with uncontrolled hypertension and their future risk of hard cardiovascular and cerebrovascular outcomes. However, hypertension in childhood is linked to hypertensive-mediated organ damage (HMOD) which is often reversible if treated appropriately. Despite differing guidelines regarding the threshold for defining hypertension, there is consensus that early recognition and prompt management with lifestyle modification escalating to antihypertensive medication is required to ameliorate adverse outcomes. Unfortunately, many unknowns remain regarding pathophysiology and optimum treatment of childhood hypertension.

Hypertension in adolescents: The role of obesity and family history

We evaluated the combined effect of obesity and family history (FH) on the risk of hypertension in adolescents. We studied 1288 school‐aged adolescents aged 16.0 ± 0.5 years (49.0% males) attending the medical examination for enrollment in the city of Nanning, China. Their blood pressure, weight, and height were measured. A questionnaire was administered to both adolescents and their parents to obtain information on the participants’ medical history. Multiple logistic regression analysis, according to bodyweight categories and adjusted for age, gender, and body mass index (BMI), was done to determine the association of FH with hypertension. Hypertension was found in 14.1% of adolescents. The prevalence of hypertension was significantly higher in adolescents with obesity and positive FH than their normal weight and negative FH counterparts. For adolescents with normal weight and waist circumstance (WC), those with a positive FH in parents compared to those without had an significantly increased risk for hypertension (odds ratio [OR], 2.15; 95% confidence interval [CI] 1.28–3.61, and 1.96; 95% CI 1.16–3.32, respectively). These findings were adjusted for age, gender, and BMI. Our study showed that routine screening for pediatric hypertension should be performed in adolescents who are overweight and obese. Furthermore, parental FH of hypertension played an important role in predicting the hypertension phenotype among adolescents with normal weight.

Association of Genetic Variants With Body-Mass Index and Blood Pressure in Adolescents: A Replication Study

The strong correlation between adiposity and blood pressure (BP) might be explained in part by shared genetic risk factors. A recent study identified three nucleotide variants [rs16933812 (PAX5), rs7638110 (MRPS22), and rs9930333 (FTO)] associated with both body mass index (BMI) and systolic blood pressure (SBP) in adolescents age 12-18years. We attempted to replicate these findings in a sample of adolescents of similar age. A total of 713 adolescents were genotyped and had anthropometric indicators and blood pressure measured at age 13, 15, 17, and 24years. Using linear mixed models, we assessed associations of these variants with BMI and SBP. In our data, rs9930333 (FTO) was associated with body mass index, but not systolic blood pressure. Neither rs16933812 (PAX5) nor rs7638110 (MRPS22) were associated with body mass index or systolic blood pressure. Although, differences in phenotypic definitions and in genetic architecture across populations may explain some of the discrepancy across studies, nucleotide variant selection in the initial study may have led to false-positive results that could not be replicated.

Influence of Dietary Approaches to Stop Hypertension-Type Diet, Known Genetic Variants and Their Interplay on Blood Pressure in Early Childhood

There is limited evidence on association between adherence to the Dietary Approaches to Stop Hypertension (DASH diet) and a lower blood pressure (BP) in children. In a population-based cohort study, among 1068 Dutch children aged 5 to 7, we evaluated the association between a DASH-type diet, 29 known genetic variants incorporated in a genetic risk score, and their interaction on BP. We calculated DASH score based on the food intake data measured through a validated 71-item food frequency questionnaire. In our sample, DASH score ranged from 9 (low adherence to the DASH diet) to 33 (median=21), and genetic score ranged from 18 (low genetic risk on high BP) to 41 (median=29). After adjustment for covariates, each 10 unit increase in DASH score was associated with a lower systolic BP of 0.7 mm Hg ( P =0.033). DASH score was negatively associated with hypertension (odds ratio=0.96 [0.92–0.99], P =0.044). Similarly, each SD increment in genetic score was associated with 0.5 mm Hg higher diastolic BP ( P =0.002). We found a positive interaction between low DASH score and high genetic score on diastolic BP adjusted for BP risk factors (β=1.52, P interaction =0.019 in additive scale and β=0.03, P interaction =0.021 in multiplicative scale). Our findings show that adherence to the DASH-type diet, as well as a low (adult-derived) genetic risk profile for BP, is associated with lower BP in children and that the genetic basis of BP phenotypes at least partly overlaps between adults and children. In addition, we found evidence of a gene-diet interaction on BP in children.

Pre-pregnancy parental BMI and offspring blood pressure in infancy

AIMS

A growing body of evidence suggests that a higher maternal pre-pregnancy body mass index results in higher offspring's blood pressure, but there is inconsistency about the impact of father's body mass index. Furthermore, evidence is limited with regard to low and middle income countries. We aimed to determine the association between parental pre-pregnancy body mass index and offspring's blood pressure during the first year of life.

METHODS

In 587 infants of the BReastfeeding Attitude and Volume Optimization (BRAVO) trial systolic and diastolic blood pressure were measured twice at the right leg in a supine position, using an automatic oscillometric device at day 7, month 1, 2, 4, 6, 9 and 12. Parental pre-pregnancy body mass index was based on self-reported weight and height. Linear mixed models were performed to investigate the associations between parental pre-pregnancy body mass index and offspring blood pressure patterns.

RESULTS

Each unit increase in maternal body mass index was associated with 0.24 mmHg (95% confidence interval 0.05; 0.44) and 0.13 mmHg (0.01; 0.25) higher offspring's mean systolic and diastolic blood pressure, respectively, during the first year of life. A higher offspring blood pressure with increased maternal pre-pregnancy body mass index was seen at birth and remained higher during the first year of life. The association with systolic blood pressure remained similar after including birth size and offspring's weight and height over time. The association with diastolic blood pressure attenuated slightly to a non-significant result after including these variables. Paternal body mass index was not associated with offspring's blood pressure.

CONCLUSION

Higher maternal pre-pregnancy body mass index, but not paternal pre-pregnancy body mass index, is associated with higher offspring blood pressure already from birth onwards.

The Additive Interaction between Body Mass Index and Hypertension Family History in Han and Yugur: The China National Health Survey (CNHS)

OBJECTIVE

To estimate the additive interaction of body mass index (BMI) and family history of hypertension (FHH) on hypertension and explore whether the interaction could be influenced by behavioural risk factors.

METHODS

The cross-sectional data on 5791 participants were from the China National Health Survey in Gansu province in 2016. We assessed the additive interaction by calculating the relative excess risk due to interaction (RERI), the attributable proportion due to interaction (AP), and the synergy index (SI).

RESULTS

ORs for hypertension were highest in Han (13.52, 95% CI: 9.45 to 19.34) and Yugur (13.85, 95% CI: 8.48 to 22.63) with the combination of obesity and FHH. The interaction of BMI and FHH was significant in Han people, with the RERI, AP, and SI and their 95% CIs being 2.48 (1.13 to 3.82), 0.33 (0.19 to 0.47), and 1.61 (1.26 to 2.07) for overweight and FHH and 6.32 (1.91 to 10.73), 0.47 (0.27 to 0.67), and 2.02 (1.33 to 3.07) for obesity and FHH, respectively. The interaction of BMI and FHH was not significant in Yugur people. Adjustment for behavioural risk factors had little influence on the interactions, and risks of hypertension remained increased.

CONCLUSIONS

BMI and FHH were associated with hypertension, and the interaction of BMI and FHH on hypertension was significant in Han but not in Yugur people. Behavioural risk factors had little influence on the associations and interactions. The exacerbation of hypertension risks by overweight or obesity in hypertension families deserves attention in weight control and community care.

Hypertensive disorders of pregnancy and cardiometabolic outcomes in childhood: A systematic review

Background

Hypertensive disorders of pregnancy (HDPs) are among the leading causes of maternal and perinatal morbidity and mortality worldwide and have been suggested to increase long-term cardiovascular disease risk in the offspring.

Objective

The objective of this study was to investigate whether HDPs are associated with cardiometabolic markers in childhood.

Search strategy

PubMed, The Cochrane Library and reference lists of included studies up to January 2019.

Selection criteria

Studies comparing cardiometabolic markers in 2–18-year-old children of mothers with HDP in utero, to children of mothers without HDP.

Data collection and analysis

Sixteen studies reported in 25 publications were included in this systematic review, of which three were considered as having high risk of bias. Thus 13 studies were included in the evidence synthesis: respectively two and eight reported pregnancy induced hypertension and preeclampsia, and three studies reported on both HDPs.

Main results

Most studies (n = 4/5) found a higher blood pressure in children exposed to pregnancy induced hypertension. Most studies (n = 7/10) found no statistically significantly higher blood pressure in children exposed to preeclampsia. No association was found between exposure to HDP and levels of cholesterol, triglycerides or glucose (n = 5/5). No studies investigated an association with (carotid) intima-media thickness, glycated haemoglobin or diabetes mellitus type 2.

Conclusions

Most studies showed that exposure to pregnancy induced hypertension is associated with a higher offspring blood pressure. There is no convincing evidence for an association between exposure to preeclampsia and blood pressure in childhood. Based on current evidence, exposure to HDP is not associated with blood levels of cholesterol, triglycerides and glucose in childhood.

Combined association of cardiorespiratory fitness and family history of hypertension on the incidence of hypertension: a long-term cohort study of Japanese males

Family history of hypertension (FH) is a nonmodifiable risk factor for hypertension. However, cardiorespiratory fitness (CRF) is a modifiable risk factor and might be important for preventing hypertension in both people with and without FH. The purpose of this study was to investigate the combined association of CRF and FH on the incidence of hypertension in normotensive male Japanese workers. A total of 6890 workers were included in this study. CRF was determined using a submaximal exercise test. A self-reported questionnaire was used to determine FH. Six groups were established, combining the two groups with and without FH (Yes, No) and the three CRF groups (Low, Moderate, High). The incidence of hypertension, defined as systolic blood pressure of ≥140 mmHg or diastolic blood pressure of ≥90 mmHg, or self-reported physician-diagnosed hypertension was evaluated. During the observation period of 101,212 man-years (median 17 years, minimum 1 year, maximum 23 years), 2210 workers developed hypertension. There were 3860 participants who had FH (56%). Compared with the Yes-Low CRF group, the HRs (95% CI) for hypertension were 66% lower in the No-High CRF group (0.34 [0.28-0.40]), 47% lower in the No-Low CRF group (0.53 [0.46-0.61]), and 24% lower in the Yes-High CRF group (0.76 [0.67-0.86]). FH and CRF did not show a significant interaction (p for interaction = 0.181). The combination of FH and CRF showed a clear association with the risk of incident hypertension, and moderate to high levels of CRF might be equally beneficial for preventing hypertension for both people with and without FH.

Familial aggregation of first degree relatives of children with essential hypertension

PURPOSE

Determining familial aggregation is an important first step in narrowing the search for disease-causing genes and hence we determined the familial aggregation of EH among first degree relatives of children with EH.

MATERIALS AND METHODS

We prospectively enrolled children with EH along with their first degree relatives from a tertiary pediatric hypertension clinic in a large ambulatory care center. We utilized rigorous methodology for blood pressure (BP) measurements and diagnoses of EH to reduce the heterogeneity in the phenotype. For those enrolled, parental BP status was confirmed by in-clinic direct BP measurements. We also enrolled control children without EH along with their first degree relatives from the same pediatric ambulatory center.

RESULTS

In our case-control study of 153 families, the odds of having familial EH was more than 3 times higher among the cases than in controls (OR: 3.63, 95% CI: 1.85-7.12) with 71% of the cases and 41% of the controls reporting familial EH. One parent with EH was seen in 88% of the cases and 52% of the controls (OR: 6.92, 95% CI: 2.68-17.84). The odds of at least one parent (compared to neither) with EH was almost 7-fold higher, and odds of having two parents with EH was 14-fold higher among cases versus controls. The risk of EH did not go back from the first degree relative to the second degree relatives.

CONCLUSIONS

We identified familial aggregation with an increased liability of childhood onset EH with parental EH. The risk of childhood onset EH is more than doubled in the presence of EH in both parents versus in a single parent. Prediction for childhood-onset EH is improved by obtaining a family history of EH in the first degree relatives.

Growth of Cardiovascular Structures from the Fetus to the Young Adult

The size, hemodynamics, and function of cardiovascular structures change dramatically from the early fetal life to late adolescence. The principal determinants of cardiovascular dimensions are related to the blood flow needed to meet metabolic demands. This demand is in turn tightly related to body size and body composition, keeping in mind that various tissues may have different metabolic rates. There is no simple model that links cardiac dimensions with a single body size measurement. Consequently, despite abundant scientific literature, few studies have proposed pediatric reference values that efficiently and completely account for the effect of body size. Other factors influence cardiovascular size and function in children, including sex. The influence of sex is multifactorial and not fully understood, but differences in body size and body composition play an important role. We will first review the determinants of cardiovascular size and function in children. We then explore the evaluation and normalization of cardiovascular size and function in pediatric cardiology in relation to the growth of cardiovascular structures during childhood, with a particular focus on sex differences.