Epigenetics, age and heredity
Johns Hopkins University scientists working under the guidance of Professor Andrew P. Feinberg have found that the profile of epigenetic markers – chemical residues that modify DNA molecules – changes as a person ages, and the degree of changes is similar among members of the same family. The authors believe that, in general, genomic health is an inherited factor, and epigenetic changes observed during life explain the increasing predisposition to the development of various diseases with age.
If epigenetics contributes to the development of diseases such as, for example, diabetes, autism and cancer through interaction with environmental factors and aging processes, then the epigenetic markers of an individual will inevitably change over time. To test this hypothesis, the authors, together with specialists from the University of Iceland, studied methylation – the attachment of a methyl group to DNA molecules, which causes the appearance of one of the most common types of epigenetic markers.
Inadequate levels of methylation can lead to the development of various diseases. An excess of methyl residues can inactivate important genes, and insufficient DNA methylation can activate any genes at the wrong time or in the wrong cells. The level of methylation varies significantly from person to person, so it is optimal to study the temporal changes of this parameter on the same individuals.
The researchers used DNA samples from the AGES Reykjavik Study participants. As part of this study, 600 individuals provided DNA samples in 1991, 2002 and 2005. The authors estimated the total number of methylated DNA fragments in 111 samples obtained in 1991 and compared the results with the data obtained from the study of DNA samples of the same 111 individuals obtained in 2002 and 2005.
They found that approximately 30% of the participants had significantly changed methylation levels over the course of 11 years, but these changes were multidirectional. In some individuals, the overall level of methylation increased, while in others it decreased. Thus, evidence has been obtained that human epigenetics does change over time. However, the causes and mechanisms of this remained unknown, and the authors suggested that the nature of these changes is inherited and underlies the family predisposition to various diseases.
After that, the scientists assessed the overall degree of changes in the level of methylation in the DNA of Utah residents of North and South European origin. DNA samples were collected for 16 years from 126 individuals representing 2-3 generations of the same families.
As well as the Icelandic population, Utah residents have demonstrated different variants of methylation changes over time. However, it turned out that for members of the same family, methylation changes usually have a similar character. For example, if one of the family members had a decrease in the level of methylation, similar changes were observed in his relatives in the other two generations.
To date, there is no concrete evidence of the role of such changes in people's health, however, according to epidemiologists, this fact is of great interest, because epigenetic changes can be an important link between the environment, aging and the risk of developing various diseases.
Portal "Eternal youth" www.vechnayamolodost.ru based on the materials of ScienceDaily
26.06.2008