[Hungarian twin studies: results of four decades.]

Semmelweis Egyetem, Általános Orvostudományi Kar Radiológiai és Onkoterápiás Klinika Budapest Üllői út 78/A 1082.
Orvosi Hetilap 10/2013; 154(40):1579-1586. DOI: 10.1556/OH.2013.29707
Source: PubMed

ABSTRACT Twin studies play a role in examining the contribution of genetic variations and environmental factors responsible for the determination of phenotypic variables and of genetic linkage between genotypes. Hungarian twin studies, supported by three twin registries (among them two twin-database), date back to 1970s. Studies mainly focused on various congenital abnormalities, the effect of contraceptive pills and folic acid on the frequency of twin pregnancies, as well as psychosexual and alcohol consumptional behaviors. Monogenic Mendelian inheritance of lactose (mal)absorption was demonstrated for the first time. Hungarian Twin Registry was founded in 2007, which contributed to the current understanding on the background of several disorders, e.g. metabolic syndrome and atherosclerosis. As part of an international twin study, among others, arterial stiffness, central blood pressure, carotid intima/media thickness, venous biomechanics, body composition, lung function and smoking characteristics were also assessed. Absence of genetic background in non-alcoholic fatty liver disease and high inheritance of carotid plaque characteristics were demonstrated for the first time. The review also aims to summarize future plans of the Hungarian Twin Registry. Orv. Hetil., 2013, 154, 1579-1586.

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    ABSTRACT: 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.
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