An international group of geneticists have found that the duration of human life largely depends on the influence of the environment than on our genes. To such conclusion scientists have come, having defined, how changes with age epigenetic regulation of the genome of twins. Preprint of a study published in the repository bioRxiv.
DNA methylation is one of the factors of human aging. When it comes to the modification of the DNA molecule without changing the nucleotide sequence, which allows to consider this process to epigenetic regulation. To cytosine in the composition СpG dinucleotide (cytosine-guanine) attached methyl group (CH3) that can lead to the suppression of functions of specific genes. It is shown that with age, the methylation pattern of the genome changes. For example activated genes contribute to neurodegeneration, and suppressed the DNA, which prevents atherosclerosis.
It is believed that the pattern of methylation depends on the genetic factors. However, scientists have conducted long-term research that allowed us to determine what proportion of this type of epigenetic regulation is determined by the environment. For this, they used twin method, which was to identify epigenetic differences between twins living in Sweden.
The average age of participants, population of 385 people, was 69 years old. Volunteers for 20 years, took blood samples, of which there are provided DNA. Genetic material was analyzed, identifying methylated СpG-dinucleotide. The researchers found 1316 sites of methylation that are associated with age, while none of them did not depend on hereditary factors. On the contrary, over time the pattern of methylation in twins and relatives have become increasingly different.
According to scientists, the results of the study indicate that human aging is highly dependent on stochastic (random) effects and environmental factors, not genes. Thus, life expectancy can be significantly increased, using, for example, a healthy diet or doing physical exercises.