Age versus Genetics
Heredity, environment, age – all this matters for health, but which of these is the most important? A new study by the University of California at Berkeley has shown that in many cases, age plays a more important role than genetics in turning on and off the genes that determine the propensity for diseases.
During the study of the relative influence of genetic profile, age and environment on the expression of about 20,000 human genes, the group found that as they age, age and external factors are much more important than individual genetic variations.
The expression of genes, that is, an increase or decrease in their activity, determines everything – from the level of hormones and metabolism to the mobilization of enzymes that restore the body. The researchers wondered: how does the genome affect susceptibility to age-related diseases? And we got the answer: genetics actually matters less the older a person gets.
In other words, the genome helps predict gene expression at a younger age, but it is less useful for predicting which genes will be more or less active as they age – in this study in people over 55. For example, identical twins have the same set of genes, but their gene expression profiles diverge with age, which means that brothers can age in completely different ways.
Medawar 's hypothesis
The results obtained are consistent with Medavar's hypothesis: genes that turn on at a young age are more susceptible to evolutionary changes because they are crucial for survival, reproduction and preservation of the species, while genes expressed at the end of reproductive age are subject to less evolutionary pressure. Thus, much more diversity can be expected in how genes are expressed later in life.
The relative role of genetic profile and age in gene expression depending on evolutionary constraints. Genes located closer to the X-axis are more "controlled" by evolution and, therefore, are more likely to play an important role in the development of human diseases.
This study is interesting because it examines both aging and gene expression in a wide range of tissues and individuals. The authors built a statistical model to assess the relative role of genetics and aging on 27 different human tissues in almost 1,000 people and found that the influence of age for different tissues varies widely – more than twenty times.
The researchers also found that Medawar's hypothesis is not true for all tissues. Surprisingly, in five types of tissues, evolutionarily important genes in older people were expressed at higher levels. From the point of view of evolution, this is illogical: it is these five tissues that must be constantly updated throughout life, and therefore the greatest number of oncological diseases occur in them. Every time the tissues regenerate, there is a risk of a genetic mutation that can lead to disease.
Apparently, this indicates the limitations of evolution. For example, blood cells must divide constantly, so these super-stable, very important genes must continue to work at the end of life. This means that these genes can accumulate mutations and continue to work in a bad, malignant state. This gives some idea of what the limitations of life are.
The study indirectly indicates the influence of the environment on aging. These are air, water, food and the level of physical activity. The environment accounts for up to a third of the changes in gene expression in the elderly.
The group is conducting a similar analysis of the expressed genes of other organisms – mice and bats - to identify differences and find out if they are related to the different life spans of these animals.
Article by R.Yamamoto et al. Tissue-specific impacts of aging and genetics on gene expression patterns in humans is published in the journal Nature Communications.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on the materials of UC Berkeley: Age vs. genetics: Which is more important for how you age?