Correlates of family history of coronary artery disease in children

Risk for hypertension crosses generations in the community: a multi-generational cohort study

Aims

Parental hypertension is known to predict high blood pressure (BP) in children. However, the extent to which risk for hypertension is conferred across multiple generations, notwithstanding the impact of environmental factors, is unclear. Our objective was therefore to evaluate the degree to which risk for hypertension extends across multiple generations of individuals in the community.

Methods and results

We studied three generations of Framingham Heart Study participants with standardized blood pressure measurements performed at serial examinations spanning 5 decades (1948 through 2005): First Generation (n = 1809), Second Generation (n = 2631), and Third Generation (n = 3608, mean age 39 years, 53% women). To capture a more precise estimate of conferrable risk, we defined early-onset hypertension (age <55 years) as the primary exposure. In multinomial logistic regression models adjusting for standard risk factors as well as physical activity and daily intake of dietary sodium, risk for hypertension in the Third Generation was conferred simultaneously by presence of early-onset hypertension in parents [OR 2.10 (95% CI, 1.66-2.67), P < 0.001] as well as in grandparents [OR 1.33 (95% CI, 1.12-1.58), P < 0.01].

Conclusion

Early-onset hypertension in grandparents raises the risk for hypertension in grandchildren, even after adjusting for early-onset hypertension in parents and lifestyle factors. These results suggest that a substantial familial predisposition for hypertension exists, and this predisposition is not identical when assessed from one generation to the next. Additional studies are needed to elucidate the mechanisms underlying transgenerational risk for hypertension and its clinical implications.

Thiobarbituric acid-reactive substances relate to arterial stiffness and blood pressure in 6 to 8-year-old boys stratified by maternal risk

Early cardiovascular disease (CVD) onset can be inflicted by familial cardiovascular and lifestyle risk factors. We aimed to compare phenotypic characteristics and explore associations between oxidative stress and vascular function in boys stratified by maternal cardiovascular and lifestyle risk. We included 40 Black and 41 White boys (ages 6-8 years), along with the biological mother of each child. The study population was divided into two groups (nonmaternal risk vs. maternal risk) according to maternal risk predetermined by their selfreported cardiovascular and lifestyle risk factors. Pulse wave velocity (PWV) was measured at various sites and blood pressures were recorded. Urine samples were collected for analyses of thiobarbituric acid-reactive substances (TBARS), 8-hydroxy-2-deoxy guanosine (8-OHdG), albumin, and creatinine. Higher levels of urinary albumin to creatinine ratio (uACR) were found in the maternal risk group compared to the nonmaternal risk group (p = .038). Multiple regression analysis in the maternal risk group revealed diastolic blood pressure (R² = 0.159; β = 0.293; p = .050), carotid femoral PWV (R² = 0.158; β = 0.297; p = .038) and carotid dorsalis pedis PWV (adj R² = 0.322; β = 0.505; p < .001) to be positively associated with TBARS, while an inverse association of uACR (R² = 0.161; β = -0.261; p = .046) with TBARS was observed. Also, in the maternal risk group, independent associations of DBP (R² = 0.273; β = 0.289; p = .040) and uACR (R² = 0.283; β = 0.268; p = .027) with 8-OHdG were indicated. In boys, as young as 6 years of age, oxidative stress related to arterial stiffness and diastolic blood pressure was observed. This association was only evident in boys with linked maternal lifestyle and cardiovascular risk factors, suggesting potential family-related early onset of cardiovascular risk.

Family history of myocardial infarction, stroke and diabetes and cardiometabolic markers in children

AIMS/HYPOTHESIS

Despite the overlap in occurrence of cardiovascular disease (CVD) and type 2 diabetes and their risk factors, family history of these diseases has not yet been investigated simultaneously in relation to cardiometabolic markers in offspring. We examined how a family history of CVD and/or diabetes relates to cardiometabolic markers in offspring, and to what extent these diseases independently contribute to cardiometabolic markers.

METHODS

We used data from 1,374 12-year-old children and their parents participating in a birth cohort study in the Netherlands. Family history of CVD (myocardial infarction [MI] and stroke) and diabetes were reported by the parents. Children were classified as 'no', 'moderate' or 'strong' family history, based on early/late onset of disease in parents and grandparents. Cardiometabolic markers were measured at 12 years of age: waist circumference, cholesterol, blood pressure and HbA1c.

RESULTS

Compared with those with no family history, children with a strong family history of MI and/or stroke and/or diabetes (29% of the study population) had 0.13 mmol/l higher total cholesterol (TC) (95% CI 0.03, 0.23) and 0.18 higher TC/HDL-cholesterol (HDLC) ratio (95% CI 0.04, 0.32). A strong family history of MI or diabetes was independently associated with unfavourable cardiometabolic markers specific to those diseases. These associations remained after adjusting for BMI. Children with a moderate family history had no unfavourable cardiometabolic markers.

CONCLUSIONS/INTERPRETATION

One-third of the children had a strong family history of CVD and/or diabetes. These children had higher TC levels and TC/HDLC ratios than children with no family history. A strong family history of MI or diabetes was independently associated with unfavourable cardiometabolic markers specific to those diseases.

Genes, environment, and cardiovascular disease

In this essay, we call to attention what every medical researcher knows about the etiology of cardiovascular disease but most deny, or choose to ignore, when designing, carrying out, and reporting genetic studies. Medical research is entering an era of synthesis that will take advantage of the successes of reductionism over the past decade in defining and describing human genome variations. Meaningful insights into the role of such variation requires a biological model of genome-phenotype relationships that incorporates interactions between subsets of possible genetic and environmental agents as causations in particular contexts indexed by time and space. We make recommendations for what needs to be done to cope with these complexities.

New atherosclerosis risk factors in obese, hypertensive and diabetic children and adolescents

In the last few years it has been proved that risk factors for atherosclerosis are present in children and adolescents, and that already at this early age they are connected with anatomic, atheromatous changes in vessels. These changes can not be fully explained as occurring in young people exhibiting traditional risk factors for the disease. The aim of the study was to evaluate levels of several new atherosclerosis risk factors (lipoprotein (a) (Lp(a)), apolipoprotein A-I (Apo A-I), apolipoprotein B (Apo B), homocysteine (Hcy), fibrinogen (FB), tissue plasminogen activator (t-PA) and tissue plasminogen activator inhibitor type 1 (PAI-1)) in children and adolescents with traditional risk factors (obesity, hypertension, diabetes).

MATERIALS AND METHODS

The study group consisted of 285 children and adolescents aged 14.3 years. Children were divided according to their main disease into groups: group A, children with obesity (n=49); group B, children with obesity and coexisting hypertension (n=56); group C, children with hypertension (n=58) and group D, children with diabetes (n=122). Control group consisted of 79 healthy children and adolescents aged 14.1 years. Lp(a), Apo A-I and Apo B levels were estimated by use of immunoturbidimetric methods; total Hcy, FB, t-PA and PAI-1 were estimated by use of immunoenzymatic methods.

RESULTS

Lp(a) level in the total study group was 30 mg/dl and was over twice higher than in control group, 14 mg/dl. Apo A-I level was significantly lower in group A (127.6 mg/dl) and in group B (125.8 mg/dl) versus 135.6 mg/dl in controls. The level of Apo B was significantly higher in total study group (86.2 mg/dl) and in groups A, B and D versus 73.5 mg/dl in controls. Hcy was higher in group B (8 micromol/l) and in group C (9.4 micromol/l) versus 6.2 micromol/l in the control group. The FB level was higher in the total study group (276.7 mg/dl) and in groups A (318.8 mg/dl) and B (322.6 mg/dl) versus 252.8 mg/dl in controls. Significantly higher t-PA level was found in groups A (9 ng/ml) and B (9.7 ng/ml) versus 7.3 ng/ml in controls, and PAI-1 level was significantly higher in the total study group (62.3 ng/ml) and in groups A (73.8 ng/ml), B (78 ng/ml) and C (73 ng/ml) versus 42.4 ng/ml in the control group. Correlation analysis showed significant relationship between body mass index (BMI) and Apo B, Hcy, FB, t-PA and PAI-1. Blood pressure values correlated positively with Hcy. Correlations were verified in multiple regression analysis models: FB and t-PA levels depended on BMI, and Hcy depended on systolic blood pressure.

CONCLUSIONS

(1) Young obese, hypertensive and diabetic patients present significant disturbances in lipid metabolism, regarding mainly total cholesterol, LDL, triglycerides, as well as Lp(a), Apo A-I and Apo B levels. Unfavourable lipid profile is characteristic mainly for children with obesity and accompanying hypertension. (2) Elevated Hcy levels are found in children with hypertension. (3) Elevated FB level and diminished fibrinolytic activity are characteristic of obese children.

Family-centered approaches to understanding and preventing coronary heart disease

Family history represents the contributions and interactions of unique genomic and ecologic factors that affect the metabolic profile and life course of a family and its members. It is well known that a family history of coronary heart disease (CHD) is a significant predictor of an individual's risk for CHD even after adjusting for an individual's own established risk factors, such as hypertension, smoking, and abnormal lipoprotein levels. The explanation for the observed familial disease aggregation is not well understood except for the general knowledge that genetic and environmental factors predisposing to CHD also aggregate in families. Given the multifactorial nature of an individual's risk, it can be argued that an individual's familial risk of disease may, in fact, be a better indicator of the many complex interactions among predisposing genetic and environmental factors than can be captured by an individual's own risk factors. Issues of how to assess, quantitate, and apply family history information in clinical settings still need to be resolved. Some clinical risk indicators, such as the National Cholesterol Education Program III guidelines, take into account family history, while others, such as the Framingham Risk Score, do not. Moreover, several family-centered intervention studies have demonstrated the particular advantages of focusing on families rather than just individuals. Although there has been tremendous progress in primary prevention of CHD over the last 20 years, substantial advancements may still be achieved by focusing on the family as its own unit of inference and as a specific target for disease prevention.

Family studies: their role in the evaluation of genetic cardiovascular risk factors

Early epidemiological studies showed that genetic factors contribute to the risk of cardiovascular disease. Genetic epidemiological studies based upon families can be used to investigate familial trait aggregation, to localize genes implicated in cardiovascular diseases in the human genome, and to establish the role of environmental factors. Family studies can be also used to identify the physiological role of candidate genes for cardiovascular diseases, and to characterize shared environmental risk factors and their impact on the expression of genetic predisposition. The present paper reviews the existing family studies with special emphasis on those which have studied healthy populations in relation to cardiovascular disease such as the Framingham Heart Study, the National Heart, Lung, and Blood Institute Family Heart Study, and the STANISLAS cohort.

Context-dependent genetic effects in hypertension

There is a growing frustration with the limitations and inconsistencies of single locus candidate gene association and linkage studies. This frustration is exacerbated by the knowledge that a large influx of genotypic and gene expression data is expected to emerge over the next 5 years, and we are not prepared for the type of multigenic conceptual framework that will be necessary to analyze that data. A review of the hypertension genetic literature reveals substantial evidence for the importance of both genetic and environmental contexts on the mapping between single locus polymorphisms and risk of disease. These trends indicate that the current reliance on simple single gene studies to elucidate the complex etiology of hypertension needs to undergo some kind of transformation. It is suggested that even a minor shift to a more systematic investigation of context-dependent effects will increase our understanding of the multidimensional genetic and environmental realities underneath current studies. This shift is also necessary if we are to gain a deeper understanding of the specific ways in which an individual's risk of hypertension is a consequence of the inter- actions among genes and environments.

Utility of the predictors of coronary heart disease mortality in a longitudinal study of elderly Finnish men aged 65 to 84 years is dependent on context defined by Apo E genotype and area of residence

A common assumption underlying most genetic studies is that individuals with different genotypes respond similarly to exposure to internal (epigenetic and background genotype effects) and external (ecological) environments. Here we evaluate whether this assumption is true in individuals with different genotypes of the gene coding for the apolipoprotein E (Apo E) molecule, an important determinant of the metabolic fate of plasma lipids and lipoproteins. We addressed whether the utility of known risk factors of coronary heart disease (CHD) in the prediction of CHD death in a 5-year follow-up is the same for the two most common Apo E genotypes, epsilon3/3 and epsilon4/3, in two cohorts of elderly Finnish men (age at baseline: 65-84 years), one in Eastern and the other in Southwestern Finland. The CHD mortality rate was higher in the epsilon4/3 than in the epsilon3/3 genotype in both cohorts (11.1 versus 7.8%, Pr = 0.281 in the Eastern cohort and 19.6 versus 8.2%, Pr = 0.002 in the Southwestern cohort). In the Eastern cohort, serum high density lipoprotein (HDL) cholesterol level was identified as a strong predictor of CHD death in the epsilon3/3 genotype (beta = -2.155, Pr = 0.019). In the Southwestern cohort, age (beta = 0.139, Pr = 0.006), body mass index (BMI) (beta = 0.149, Pr = 0.016), and serum total cholesterol level (beta = 0.453, Pr = 0.051) were identified as strong predictors in the epsilon3/3 genotype, as were smoking (beta = 0.236, Pr = 0.008) and BMI (beta = -0.124, Pr = 0.057) in the epsilon4/3 genotype. The latter observation indicates that in Southwestern Finland the probability of CHD death decreases with increasing BMI in elderly men with the epsilon4/3 genotype, while in their counterparts with the epsilon3/3 genotype the risk increases with increasing BMI. This difference was statistically significant (Pr = 0.002). These observations clearly argue against the assumption that individuals with different genotypes respond similarly to exposures to internal and/or external environments. These observations are consistent with a complex pathobiology of CHD involving biochemical and physiological agents that are under the influence of interactions between genetic and environmental factors. Information about these interactions is necessary for developing a more precise risk assessment and ultimately to improve public health and clinical strategies to prevent this devastating disease both at the individual and population levels.