Heritability of Vascular Structure and Function: A Parent-Child Study

Heritability of carotid intima-media thickness and inflammatory factors of atherosclerosis in a Chinese population

Carotid intima-media thickness (cIMT), a marker of subclinical atherosclerosis, has been found to be associated with incident stroke. High-sensitivity C-reactive protein (CRP) and fibrinogen have been demonstrated to be associated with atherosclerosis. Previous studies on heritability estimates of IMT, CRP, and fibrinogen among Chinese populations are limited. This study aims to estimate the heritability of these risk factors in residents who participated in the Taichung Community Health Study (TCHS) and their family members. A total of 2671 study subjects from 805 families were enrolled in the study, selected from a random sample of TCHS participants and their family members. CRP, and fibrinogen were obtained from each participant, and a questionnaire interview was conducted. cIMT was measured by high-resolution B-mode ultrasound and expressed as the mean of the maximum. Heritability estimates and the familial correlation of cIMT, CRP, and fibrinogen among family pairs were determined with SAGE software. With multivariate adjustments, significant heritability was found for cIMT (h2 = 0.26, P < 0.001), CRP (h2 = 0.34, P < 0.001), and fibrinogen (h2 = 0.48, P < 0.001). The intrafamilial correlation coefficients for the three indexes in the parent-offspring pairs were significant (P < 0.001) and ranged from 0.17 to 0.41. The full sibship correlations were also significant (P < 0.001) for the three indexes and ranged from 0.19 to 0.47. This study indicates that a moderate proportion of the variability in CRP, fibrinogen, and cIMT can be attributed to genetic factors in Chinese populations. The findings suggest that CRP is associated with cIMT, whereas no significant association exists between fibrinogen and cIMT.

Influencing factors of supernormal vascular aging in Chinese population

OBJECTIVES

Previous studies have analysed the epidemic characteristics of supernormal vascular aging (SUPERNOVA), and found that SUPERNOVA were significantly associated with lower risk of cardiovascular disease. However, the influencing factors of SUPERNOVA are still unclear. The aim of this study was to investigate the characteristics and influencing factors of SUPERNOVA.

METHODS

A total of 42 196 participants of the Kailuan Study were enrolled in the study. SUPERNOVA was defined as the lowest 2.5% of the age-quintile brachial-ankle pulse wave velocity (baPWV), early vascular aging was defined as the highest 2.5% of the age-quintile baPWV. Multivariable logistic regression analysis was applied to investigate the influencing factors of SUPERNOVA.

RESULTS

The population with SUPERNOVA was mostly women, nonsmokers, nondrinkers, and those with higher education. They had lower levels of cardiovascular disease risk factors and healthier lifestyles. The results of logistics regression showed that the influencing factors of SUPERNOVA include age, sex, hypertension, diabetes, resting heart rate, hypersensitive C-reactive protein, and uric acid. However, the effects of these factors were different across age groups. We also observed that in addition to the unalterable factors (age and sex), only resting heart rate above 80 bpm (OR = 0.396, 95% CI: 0.231-0.681) and SBP (OR = 0.945, 95% CI: 0.932-0.958) were significantly associated with odds of SUPERNOVA in participants without cardiovascular risk factors.

CONCLUSION

This study investigated the characteristics of the population with SUPERNOVA and the factors influencing it, which provided a basis for different populations to take preventive measures to slow down the process of vascular aging.

Effect of parental arterial stiffness in offspring: the Kailuan study

OBJECTIVE

The aim of this study was to examine effect of parental arterial stiffness in offspring.

METHODS

The individuals who participated in the second or subsequent follow-up and had parent-offspring relationship and completed measurements of brachial-ankle pulse wave velocity (baPWV) from the Kailuan study were recruited. The individuals were divided into groups by the 10-year intervals and sex. Arterial stiffness was defined as the 75th percentiles in each age category. Multivariable generalized estimating equations was used to analyse the effect of parental baPWV and blood pressure in offspring. Multivariable logistic regression using generalized estimating equations was used to analyse the effect of parental arterial stiffness in offspring.

RESULTS

A total of 4514 parents and offspring who met the inclusion criteria, including 1785 paternal offspring and 625 maternal offspring was recruited. Mean age of paternal offspring and maternal offspring were 36.26 (SD 7.86) and 36.42 (SD 7.57) years, while their mean baPWV were 1294.40 (SD 225.32) and 1270.74 (SD 241.42) cm/s, respectively. In multivariate linear regression analyses, after adjusted for the covariate risk factors, an increase of 1 cm/s in the paternal and maternal baPWV of resulted in an increase of 0.05 and 0.30 cm/s in offspring, respectively. In multivariate logistic regression analyses, the risk of arterial stiffness in the offspring of paternal and maternal arterial stiffness increased by 50 and 77%, respectively.

CONCLUSION

Paternal and maternal baPWV are linear positively correlated with baPWV in offspring. Parental arterial stiffness is a risk factor for arterial stiffness of offspring and is independent of traditional risk factors of offspring arterial stiffness.

Ideal Cardiovascular Health and Vascular Phenotype Associations in Mothers with Obesity and Their Six-Year-Old Children

BACKGROUND

Heredity and family-shared lifestyle contribute to cardiovascular risk, but the magnitude of their influence on arterial structure and function in early childhood is unknown. We aimed to assess associations between child and maternal ideal cardiovascular health, maternal subclinical atherosclerosis, and child arterial phenotype.

METHODS

Cross-sectional analysis of 201 mother-child pairs originating from the Finnish Gestational Diabetes Prevention Study (RADIEL) longitudinal cohort was done at child age 6.1 ± 0.5 years with assessments of ideal cardiovascular health (BMI, blood pressure, fasting glucose, total cholesterol, diet quality, physical activity, smoking), body composition, very-high frequency ultrasound of carotid arteries (25 and 35 MHz), and pulse wave velocity.

RESULTS

We found no association between child and maternal ideal cardiovascular health but report evidence of particular metrics correlations: total cholesterol (r=0.24, P=0.003), BMI (r=0.17, P=0.02), diastolic blood pressure (r=0.15, P=0.03), and diet quality (r=0.22, P=0.002). Child arterial phenotype was not associated with child or maternal ideal cardiovascular health. In the multivariable regression explanatory model adjusted for child sex, age, systolic blood pressure, lean body mass, and body fat percentage, child carotid intima-media thickness was independently associated only with maternal carotid intima-media thickness (0.1 mm increase [95% CI 0.05, 0.21, P=0.001] for each 1 mm increase in maternal carotid intima-media thickness). Children of mothers with subclinical atherosclerosis had decreased carotid artery distensibility (1.1 ± 0.2 vs 1.2 ± 0.2%/10 mmHg, P=0.01) and trend toward increased carotid intima-media thickness (0.37 ± 0.04 vs 0.35 ± 0.04 mm, P=0.06).

CONCLUSION

Ideal Cardiovascular Health metrics are heterogeneously associated in mother-child pairs in early childhood. We found no evidence of child or maternal Ideal Cardiovascular Health effect on child arterial phenotype. Maternal carotid intima-media thickness predicts child carotid intima-media thickness, but the underlying mechanisms remain unclear. Maternal subclinical atherosclerosis is associated with local carotid arterial stiffness in early childhood.

Accelerated Early Vascular Aging Among Adolescents With Obesity and/or Type 2 Diabetes Mellitus

Background The normal rate of subclinical vascular aging from adolescence to young adulthood has not been well-characterized. We conducted a 5-year longitudinal study among adolescents with normal-weight, obesity, and/or type 2 diabetes mellitus to examine trajectories of early vascular aging. Methods and Results Adolescents (mean [SD] age 17.6 [3.5]; 35.3% male) had either normal weight (n=141), obesity (n=156), or type 2 diabetes mellitus (n=151) at baseline. Primary metrics used for early vascular aging included measures of vascular structure (carotid intima-media thickness [cIMT]; common, internal, and bulb) and arterial stiffness (carotid-femoral pulse wave velocity, and augmentation index). Longitudinal (5-year) outcomes were examined using generalized estimating equations adjusting for baseline value, sex, race, and age. Compared with participants with normal weight, those with obesity had greater positive change in common cIMT (0.05 mm [0.03, 0.06]; P<0.001), bulb cIMT (0.02 mm [0.00, 0.05]; P=0.033), internal cIMT (0.03 mm [0.01, 0.05]; P<0.001), and pulse wave velocity carotid-femoral (0.38 m/sec [0.14, 0.61]; P=0.001), and those with type 2 diabetes mellitus had greater positive change in common cIMT (0.05 mm [0.04, 0.07]; P<0.001), bulb cIMT (0.06 mm [0.04, 0.09]; P<0.001), internal cIMT (0.04 mm [0.02, 0.07]; P<0.001), augmentation index (4.67% [2.20, 7.13]; P<0.001), and pulse wave velocity carotid-femoral (0.74 m/sec [0.46, 1.02]; P<0.001). Higher baseline systolic blood pressure was associated with greater positive change in common cIMT (0.007 mm [0.003, 0.011]; P<0.001), bulb cIMT (0.009 mm [0.002, 0.016]; P=0.01), internal cIMT (0.008 mm [0.003, 0.013]; P=0.001), and pulse wave velocity carotid-femoral (0.066 m/sec [0.002, 0.130]; P=0.042). Conclusions These longitudinal data support the hypothesis that the presence of obesity, type 2 diabetes mellitus, and elevated baseline systolic blood pressure in early life accelerates the progression of risk factors key in the development of early vascular aging.

Cardiovascular Risk Factors Track From Mother to Child

Background

Cardiovascular risk factors can track from mother to child by several pathways: pregnancy complications, genetic inheritance, and shared environmental risk factors after pregnancy. The degree of tracking, and to which extent this is influenced by these pathways, is unknown. We hypothesized that cardiovascular risk factors track from mother to child regardless of pregnancy complications and environmental risk factors. We determined the degree of tracking between maternal and offspring micro‐ and macrovascular cardiovascular risk factors after pregnancy and the extent to which this is influenced by pregnancy complications and shared environmental risk factors.

Methods and Results

We included 5624 mother‐offspring pairs from The Generation R Study, an ongoing prospective, population‐based birth cohort. Information on pregnancy complications (preeclampsia, small for gestational age, and preterm birth) was obtained through hospital charts. Mother‐offspring associations were assessed 6 years after pregnancy (central retinal arteriolar and venular calibers, body mass index, blood pressure, left atrial diameter, aortic root diameter, left ventricular mass, fractional shortening, and pulse wave velocity) and 9 years after pregnancy (body mass index and blood pressure). We observed that worse cardiovascular parameters in mothers were associated with worse cardiovascular parameters in their offspring 6 and 9 years after pregnancy (P<0.001). Results were similar when mother‐offspring pairs with a previous pregnancy complication were excluded.

Conclusions

Six and 9 years after pregnancy, an adverse cardiovascular profile in mothers is strongly associated with an adverse cardiovascular profile in their offspring. Results were not attenuated by environmental exposures or a previous pregnancy complication. This supports the hypothesis that cardiovascular risk factors (micro‐ and macrovascular) track from mother to child, regardless of the course of pregnancy.

Genome-wide linkage analysis of carotid artery traits in exceptionally long-lived families

BACKGROUND AND AIMS

Atherosclerosis develops with age and is partially controlled by genetics. Research to date has identified common variants with small effects on atherosclerosis related traits. We aimed to use family-based genome-wide linkage analysis to identify chromosomal regions potentially harboring rare variants with larger effects for atherosclerosis related traits.

METHODS

Participants included 2205 individuals from the Long Life Family Study (LLFS), which recruited families with exceptional longevity from Boston, New York, Pittsburgh, and Denmark. Participants underwent B-mode ultrasonography of the carotid arteries to measure intima-media thickness (IMT), inter-adventitial diameter (IAD), and plaque presence and severity. We conducted residual heritability and genome-wide linkage analyses adjusted for age, age², sex, and field center using pedigree-based maximum-likelihood methods in SOLAR.

RESULTS

All carotid traits were significantly heritable with a range of 0.68 for IAD to 0.38 for IMT. We identified three chromosomal regions with linkage to IAD (3q13; max LOD 5.3), plaque severity (17q22-q23, max LOD 3.2), and plaque presence (17q24, max LOD 3.1). No common allelic variants within these linkage peaks were associated with the carotid artery traits.

CONCLUSIONS

We identified three chromosomal regions with evidence of linkage to carotid artery diameter and atherosclerotic plaque in exceptionally long-lived families. Since common allelic variants within our linkage peaks did not account for our findings, future follow-up resequencing of these regions in LLFS families should help advance our understanding of atherosclerosis, CVD, and healthy vascular aging.

Carotid artery intima-media thickness, distensibility and elasticity: population epidemiology and concordance in Australian children aged 11-12 years old and their parents

OBJECTIVES

To describe a well-established marker of cardiovascular risk, carotid intima-media thickness (IMT) and related measures (artery distensibility and elasticity) in children aged 11-12 years old and mid-life adults, and examine associations within parent-child dyads.

DESIGN

Cross-sectional study (Child Health CheckPoint), nested within a prospective cohort study, the Longitudinal Study of Australian Children (LSAC).

SETTING

Assessment centres in seven Australian major cities and eight selected regional towns, February 2015 to March 2016.

PARTICIPANTS

Of all participating CheckPoint families (n=1874), 1489 children (50.0% girls) and 1476 parents (86.8% mothers) with carotid IMT data were included. Survey weights and methods were applied to account for LSAC's complex sample design and clustering within postcodes and strata.

OUTCOME MEASURES

Ultrasound of the right carotid artery was performed using standardised protocols. Primary outcomes were mean and maximum far-wall carotid IMT, quantified using semiautomated edge detection software. Secondary outcomes were carotid artery distensibility and elasticity. Pearson's correlation coefficients and multivariable linear regression models were used to assess parent-child concordance. Random effects modelling on a subset of ultrasounds (with repeated measurements) was used to assess reliability of the child carotid IMT measure.

RESULTS

The average mean and maximum child carotid IMT were 0.50 mm (SD 0.06) and 0.58 mm (SD 0.05), respectively. In adults, average mean and maximum carotid IMT were 0.57 mm (SD 0.07) and 0.66 mm (SD 0.10), respectively. Mother-child correlations for mean and maximum carotid IMT were 0.12 (95% CI 0.05 to 0.23) and 0.10 (95% CI 0.03 to 0.21), respectively. For carotid artery distensibility and elasticity, mother-child correlations were 0.19 (95% CI 0.10 to 0.25) and 0.11 (95% CI 0.02 to 0.18), respectively. There was no strong evidence of father-child correlation in any measure.

CONCLUSIONS

We provide Australian values for carotid vascular measures and report a modest mother-child concordance. Both genetic and environmental exposures are likely to contribute to carotid IMT.

Cross-sectional associations between Ideal Cardiovascular Health scores and vascular phenotypes in 11- to 12-year-olds and their parents: The Longitudinal Study of Australian Children

BACKGROUND

Understanding early-life relationships between the Ideal Cardiovascular Health (ICVH) score and vascular phenotypes could inform likely effectiveness and timing of cardiovascular disease prevention strategies. We aimed to describe associations between ICVH scores and vascular phenotypes in 11- to 12-year-old children and their parents.

METHODS AND RESULTS

Cross-sectional ICVH scores (range 0-7, higher indicating better health), derived by summing dichotomized metrics for cholesterol, glucose, blood pressure (BP), body mass index (BMI), diet, physical activity and smoking, were constructed for 1235 adults (89% female, mean age 43 years) and 1028 children (48% female, 12 years). The median scores were 4 and 5 for adults and children respectively. Child ICVH scores were associated with parent scores (0.18 higher child score per additional point in parent's score, 95% CI 0.12 to 0.22, P < 0.001). Each additional point in the adult ICVH score was associated with slower carotid-femoral pulse wave velocity (PWV, -0.32 m/s, 95% CI -0.37 to -0.27), greater carotid elasticity (0.017%/mm Hg, 95% CI 0.014 to 0.020) and reduced carotid intima-media thickness (IMT, -7.3 μm, 95% CI -12.0 to -2.5). An additional point in the child score was associated with functional phenotypes (PWV -0.07 m/s, 95% CI -0.11 to -0.03; carotid elasticity 0.009%/mm Hg, 95% CI 0.004 to 0.015) but not structural phenotypes (IMT -1.8 μm, 95% CI -5.2 to 1.5).

CONCLUSION

Few Australian children and even fewer parents have ideal cardiovascular health. Lower ICVH scores were associated with adverse adult vascular phenotypes and adverse child vascular function. Family-based interventions optimizing ICVH metrics may delay onset and progression of subclinical atherosclerosis and later cardiovascular disease.

Carotid Artery Atherosclerosis: A Review on Heritability and Genetics

Carotid atherosclerosis (CAS) is associated with increased cardiovascular risk, and therefore, assessing the genetic versus environmental background of CAS traits is of key importance. Carotid intima-media-thickness and plaque characteristics seem to be moderately heritable, with remarkable differences in both heritability and presence or severity of these traits among ethnicities. Although the considerable role of additive genetic effects is obvious, based on the results so far, there is an important emphasis on non-shared environmental factors as well. We aimed to collect and summarize the papers that investigate twin and family studies assessing the phenotypic variance attributable to genetic associations with CAS. Genes in relation to CAS markers were overviewed with a focus on genetic association studies and genome-wide association studies. Although the role of certain genes is confirmed by studies conducted on large populations and meta-analyses, many of them show conflicting results. A great focus should be on future studies elucidating the exact pathomechanism of these genes in CAS in order to imply them as novel therapeutic targets.