Scientists have discovered why men die before women

In the system of chromosomal sex determination, asit is known that there are two chromosomes - the female X and the male Y. The male Y chromosome contains the SRY gene, which is responsible for the production of male hormones. It is known that with age, the number of Y chromosomes in men decreases, and so much so that 40% of 70-year-old men do not have this chromosome at all. Previously, it was believed that without this chromosome you can live. In the end, women somehow manage without it. However, scientists from the University of Virginia with colleagues from Sweden and Japan came to the conclusion that not everything is so simple. Of course, the loss of a chromosome does not lead to instant death. However, against the background of its absence, a fatal disease develops, which significantly reduces life expectancy.

Scientists have found one of the causes of death of men

The Y chromosome and why men lose it

Most of the cells in the human body havea much shorter lifespan than the person himself. For example, the life span of epithelial cells does not exceed a month. But from this we do not experience problems with the skin, since some cells are destroyed, while others appear.

We will not go into all the details of the divisioncells, but note that each new cell receives a complete set of chromosomes. There are special mechanisms that are responsible for their copying and distribution to new cells. However, sometimes a glitch can occur, as a result of which the chromosomes are copied incorrectly. They may be less or, conversely, more.

Depending on how critical the error iswas made during copying, the cell may continue to exist or immediately die. If the cell with the error survives, it can cause serious problems in the body.

The fastest way for men to lose the Y chromosome in blood cells

Most often, the loss of the Y chromosome occurs incells that do not live long and are quickly updated. These include blood cells. The only thing is that the Y-chromosome is always present in male germ cells, due to which the absence of a chromosome is not inherited. As a result, genetic mosaicism can occur in men, when the Y chromosome is present in some cells, but not in some.

Smokers are known to lose their Y chromosomes especially quickly.

The fact that the loss of the “game” is associated with agediseases, scientists have long suspected. In particular, the absence of a chromosome has been associated with an increased likelihood of developing Alzheimer's syndrome. However, there was no evidence for this, and besides, it was not clearly known what kind of serious health problems the absence of a male chromosome threatens.

The absence of the male chromosome in the blood leads to the development of cardiac fibrosis

New causes of male death discovered

According to researchers, women in the United States liveabout 5 years longer than men. The situation is similar in other developed countries. Moreover, mortality among men increases after 60 years. A new study published in the journal Science seems to explain why.

“Especially after 60, men die faster than women. It's like biologically they age faster,” says Dr. Kenneth Walsh, one of the authors of the study.

The study says that the loss of malesex chromosome leads to scarring of the heart muscle. This in turn leads to fatal heart failure. In addition, as previously suggested, the risk of developing age-related diseases increases. By the way, earlier we said that sports can help fight age-related diseases and prolong the youthfulness of the brain.

Age-related diseases in men are also associated with the absence of a male chromosome.

However, the study has only been carried out onmice. The authors of the work used modern gene editing technology. She allowed mice to be modified, after which they lost the male chromosome in their blood cells. As a result, in animals, connective tissue began to accumulate in the heart, which is not able to contract. Accordingly, mice with cardiac fibrosis lived less than healthy rodents.

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How the Y chromosome causes heart fibrosis

Why does the loss of a male chromosome lead toproliferation of connective tissue in the heart? In general, the appearance of connective tissue is associated with damage. The immune system tries to eliminate them when immune inflammatory signals occur. That is, immunity stimulates the growth of this tissue. For example, connective tissue begins to grow in myocardial infarction.

In the case of the loss of the Y chromosome, according to scientists,there is no inflammation, but there is a complex picture in the composition of the blood, as a result of which the same immunity leads to fibrosis. Moreover, the connective tissue begins to grow not only in the heart, but also in other organs. But it is the heart that first reacts to such changes in the body.

If the results of this studyconfirmed, in the future, scientists will be able to combat the consequences of the loss of the Y chromosome, which will increase the life expectancy of men. Finally, let me remind you that not so long ago, scientists learned to identify the risk of early death in the eyes.