Disappearing Y Chromosome in Men
Most of us learn in school that the Y chromosome is what makes someone biologically male. Females have XX chromosomes, and males have XY chromosomes. Scientists believed that the Y chromosome is involved in only two activities: determining sex and helping in sperm production for years. Many of them thought that losing it would not seriously affect health, as it carries only 51 protein-coding genes.
But new research is changing that idea.
Recent studies have shown that more than 40% of men begin losing their Y chromosome by age 60. Nearly 57% show some loss of the Y chromosome in their cells by the time they are 90 years old. This condition is called the “loss of Y.” It happens only in some cells and not every cell in the body. This creates a mixture of cells, some with a Y chromosome and some without.
Scientists thought that it would not matter much at first. The Y chromosome is small and has fewer genes. It is the only chromosome that can be lost without immediately killing a cell. The Y chromosome has disappeared over time through evolution, even in some animals.
So why is this a big deal now?
Recent evidence suggests that loss of the Y chromosome may be linked to serious diseases.
Several studies have found that there is an increased risk of heart attacks and other cardiovascular diseases in men over 60 who lose the Y chromosome. A large study in Germany showed that older men with high Y chromosome loss were more likely to develop heart problems. This suggests that the Y chromosome may play a role in maintaining heart health.
The loss of the Y chromosome has also been linked to cancer. Many types of cancers in men show that tumor cells lack Y chromosomes. Researchers have noticed that the outcomes of cancer worsen in men with a higher loss of the Y chromosome. Scientists believe that the cells without a Y chromosome may grow faster than normal cells. This could help the tumors grow faster.
There is more. The loss of the Y chromosome has also been linked to Alzheimer’s disease. In fact, Alzheimer’s patients have been found to lose the Y chromosome at a much higher frequency.
Some studies even suggest it may help explain why men and women experience certain diseases differently. Researchers noticed that men had higher death rates during the COVID-19 pandemic. Some studies have linked this to the loss of the Y chromosome in blood cells.
Environmental factors also play an important role. There is an increased chance of losing the Y chromosome due to smoking and exposure to harmful chemicals. The Y chromosome is more likely to make mistakes during cell division, especially in tissues where cells divide quickly. Once a cell loses the Y chromosome, it cannot be regained. All the new cells derived from it will also lack the Y chromosome.
Now comes a big question. Does the loss of the Y chromosome cause these diseases, or is it just associated with them?
Researchers are still working on the answer. Some believe that health problems may lead to the loss of the Y chromosome. And some think that the loss itself may damage how certain genes work, especially those genes that are involved in immune function and heart health.
Some Y chromosome genes act as cancer suppressors besides the well-known SRY gene and sperm-related genes. Although these genes are also present on the X chromosome, loss of one copy may disrupt cellular balance.
A mouse study gave more clues. Mice showed more signs of heart failure and age-related diseases when the scientist transplanted Y-deficient blood cells into them. This demonstrates that the loss of Y chromosome may directly affect health, rather than being a side effect of aging.
The human Y chromosome was fully sequenced a few years ago. Scientists are just beginning to understand all the functions of the Y chromosome. What once seemed like a “minor” chromosome is now being studied closely.
In simple terms, losing the Y chromosome may not just be a natural part of aging. It could be a sign of warning. As the research continues, doctors may use the loss of the Y chromosome as a marker to predict heart disease, cancer, or Alzheimer’s risk in older men.
The Y chromosome may be small, but its impact on men’s health could be much bigger than we ever imagined.
