Genetic epidemiological approaches in the study of risk factors for cardiovascular disease

Transgenerational effects of parental cardiovascular disease and risk factors on offspring mortality: family-linkage data from the HUNT Study, Norway

BACKGROUND

Cardiovascular risk factors are known to be associated between parents and offspring. However, whether these associations are reflected in increased offspring mortality has not been extensively studied.

DESIGN

This was a family study of 32,536 father-offspring and 39,614 mother-offspring pairs who participated in the HUNT Study, Norway.

METHODS

Adjusted hazard ratios (HRs) for offspring total and cardiovascular mortality associated with parental levels of cardiovascular disease risk factors were estimated using Cox regression.

RESULTS AND CONCLUSIONS

Fathers' and mothers' reporting of cardiovascular disease (HRs: 1.18; 95% CI 1.04-1.32 and 1.20; 1.07-1.35, respectively), diabetes (HRs: 1.22; 95% CI 1.00-1.49 and 1.21; 1.05-1.40, respectively), and current smoking (HRs: 1.21; 95% CI 1.08-1.36 and 1.30; 1.15-1.47, respectively) was associated with total mortality in offspring. An inverse association was found with maternal height (HR: 0.95; 95% CI 0.91-0.99), and a suggestive inverse association with paternal height (HR: 0.98; 95% CI 0.93-1.03). Relations with offspring cardiovascular mortality were less clear and consistent. Offspring whose parents both had a risk factor did not seem to have higher mortality than would be expected from the independent effects of each parent.

Comparison of father-offspring and mother-offspring associations of cardiovascular risk factors: family linkage within the population-based HUNT Study, Norway

BACKGROUND

Cardiovascular risk factors are transmitted from parents to offspring; however, the relative contributions of fathers and mothers remain unclear. If maternal exposures during pregnancy influence offspring through the intrauterine environment, associations between mothers and offspring are expected to be stronger than between fathers and offspring. In this family linkage study we compared father-offspring and mother-offspring associations of several cardiovascular risk factors.

METHODS

The study population consisted of 36,528 father-mother-offspring trios who participated at one or more surveys of the HUNT Study, Norway in 1984-86, 1995-97 and 2006-08. Parent-offspring associations were assessed using unstandardized and standardized residuals from linear regression analysis, and possible non-paternity was accounted for in sensitivity analyses.

RESULTS

Age- and sex-adjusted parent-offspring associations for anthropometric factors, blood pressure, blood lipids, blood glucose and resting heart rate were largely similar between fathers and mothers. Use of standardized values and analyses adjusted for non-paternity further emphasized this similarity.

CONCLUSIONS

This study found largely similar father-offspring and mother-offspring associations across all cardiovascular risk factors under study, arguing against strong maternal effects transmitted through intrauterine mechanisms.

Tracking of cardiovascular risk factors across generations: family linkage within the population-based HUNT study, Norway

BACKGROUND

Parent-offspring studies have shown that cardiovascular risk factors cluster within families. However, most studies have assessed the offspring cardiovascular risk factor level at a young age, and whether an association persists into the offspring's adult life is less clear. This study linked information between parents and their adult offspring to investigate the intergenerational association of anthropometric measures, blood pressure, blood lipid levels and physical activity.

METHODS

The study population consisted of parent and adult offspring pairs (11,931 fathers-sons, 12,563 fathers-daughters, 15,626 mothers-sons and 16,449 mothers-daughters) who participated in the second and third cross-sectional waves of the Nord-Trøndelag Health Study (HUNT 2, 1995-1997 and HUNT 3, 2006-2008). A general linear model and logistic regression were used to estimate the association between the parent and offspring risk factor levels.

RESULTS

All continuously measured cardiovascular risk factors under study showed a statistically significant positive association between parents and offspring, except the waist-hip ratio. Adjusted coefficients from linear regression ranged from 0.09 (95% CI 0.07 to 0.11) for waist circumference to 0.29 (95% CI 0.27 to 0.32) for body weight. Moreover, offspring were two to three times more likely to be obese, have a high cholesterol level, or hypertension when comparing extreme categories of the corresponding parental risk factor level. Physically active parents had a lower risk of having physically inactive offspring.

CONCLUSIONS

The results suggested that cardiovascular risk factors track across generations and persist into the offspring's adult life.

Knowledge and attitudes towards genetic testing: a two year follow-up study in patients with asthma, diabetes mellitus and cardiovascular disease

Adequate knowledge and personal attitudes towards DNA-testing are major determinants of optimal utilization of genetic testing. This study aims to (1) assess the genetic knowledge and attitude towards genetic testing of patients with asthma, diabetes mellitus type II and cardiovascular diseases, (2) determine whether their knowledge or attitude changed since 2002, and (3) investigate the predictive role of knowledge on attitude. Data were collected within the Panel of Patients with Chronic Diseases in 2002 and 2004, resulting in 398 data-pairs. Results show that factual knowledge mainly relates to associations between genes and diseases, less is known on associations between genes, chromosomes, cells and body. The perceived knowledge on DNA-testing has not increased since 2002. The attitude towards genetic testing also appeared to be rather consistent. Less perceived medical genetic knowledge and more perceived social genetic knowledge were found predictive for a more reserved attitude towards genetic testing. In conclusion, advanced developments in the field of genetics are not accompanied by increased knowledge of patients with common multi-factorial diseases. The finding that more perceived social genetic knowledge results in more reluctance can be considered an indicator for the necessity of social debates on genetic testing.

Cardiología preventiva y rehabilitación

Preventive cardiology occupies a central place in medicine today. The subject monopolizes a large proportion of epidemiological studies and clinical trials involving a range of drugs. Moreover, preventive cardiology provided the initial impetus for regarding genetic epidemiology as a basis for disease prevention. The aim of this article was to summarize just some of the publications that have appeared during the last few months, with special emphases on obesity and diabetes mellitus as the pre-eminent risk factors for disease, and on their combination as part of the so-called metabolic syndrome.

Definition of high risk individuals to optimise strategies for primary prevention of cardiovascular diseases

The identification of high risk individuals is one of the main goals of cardiovascular primary prevention and constitutes the basis for implementing actions oriented toward reducing modifiable risk factors at individual level, from changing life styles to drug interventions. The most appropriate method for identifying high risk individuals is the evaluation of their absolute global risk, a probability indicator of incidence, predictable on the basis of risk factor levels. Risk functions, derived from longitudinal studies, are used to identify persons at high probability to develop cardiovascular diseases. The appropriateness of the use of these risk functions depends upon the characteristics of the population that generated them and of individuals which they are applied to. Risk charts are simply absolute global risks calculated by classes of risk factors; risk scores are more precise evaluation derived from absolute global risks calculated by continuous levels of risk factors. Risk charts and scores are formed through the risk functions derived from different studies: Framingham, PROCAM (Munster), Seven Countries Study, SCORE and Progetto CUORE. A further chart has been created using the Framingham Study and adapted to the guidelines of New Zealand regarding the treatment of dyslipidemias and blood pressure. Major differences can be found in the availability of risk factors in men and women and in the use of fatal and non-fatal coronary and cerebrovascular events as end-points. All these studies use different diagnostic criteria for identification, classification and validation of events. The awareness of the risk charts differences is a key issue to refine tools for prevention of cardiovascular disease in populations with different probabilities of disease frequency.