Past, present and future of cardiovascular twin studies

The increasing burden of cardiovascular disorders highlights the crucial need to research efforts in the prevention and screening of heritable disorders or cardiovascular risk factors. Twin studies offer an opportunity to assess the influence of genetic and environmental factors and gene-environment interactions as well. Blood pressure and its components, arterial stiffness, carotid intima-media thickness were found to have a moderate heritability, whereas carotid plaque formation and coronary atherosclerosis seemed to be strongly genetically determined. These findings so far underlined the importance of identification of the specific genetic factors and prevention in high-risk individuals due to genetic transmission; therefore, further studies should investigate the benefits of a possible screening program. Beyond this “classical” model, monozygotic twin pairs discordant for a disease are important research opportunity since this method is able to assess the role of prenatal and postnatal environmental (epigenetic, stochastic) factors in the development of a disease. Longitudinal twin studies provide an ideal model to investigate the within-pair epigenetic drift (e.g. DNA methylation, histone modification) over time. In the future, these twin studies might unravel the underlying epigenetic changes associated with cardiovascular disease-risk biomarkers, which can help in the identification of those individuals who have higher risk for future cardiovascular disorders. Since in most twin studies a considerable role is found for unique environmental factors, the “traditional” concept of the deterministic role of individual-specific modifiable environmental factors, such as smoking, unhealthy nutrition or reduced physical activity, still remains important.