A recent study has shown that the loss of the Y chromosome in men can cause increased risks of heart failure, cancer, Alzheimer’s, and other aging-related diseases.
The Y chromosome is one of two sex chromosomes; X and Y. Women have only two X chromosomes while men have both X and Y chromosomes. While scientists have long correlated the loss of Y chromosome to diseases and higher mortality rates, the evidence isn’t very conclusive.
The loss of Y chromosome isn’t 100% known but it has been attributed to one main cause. The Y chromosome carries less than a tenth of the X chromosome, carrying only 71 genes. Scientists theorize that because of this, the Y chromosome sometimes isn’t passed on when a cell divides.
Researchers have used blood samples as the primary form of analyzing Y chromosome absence. The Y chromosome has been found to be missing from white blood cells of 40% of 70-year-olds and 57% of 93-year-olds.
The study that molecular biologist Kenneth Walsh of the University of Virginia conducted was on mice, which are relatively anatomically and physiologically close to humans, as well as being easier to work with. After removing Y chromosomes from male mice, through blood transplants of bone marrow, the study found that mice lacking the Y chromosome had stiffer hearts. A stiff heart is when muscles and connective tissue around the heart thicken, causing shorter breath and fluid retention in the lungs and legs.
While Y chromosomes aren’t necessarily needed to survive, the study showed that without the Y chromosome in their bone marrow, the mice’s macrophages, a type of white blood cells, promoted the stiffening of the hearts. This stiffening of the hearts is also known as fibrosis which causes many circulatory issues. After the fibrosis, the contraction strength of the mice’s hearts dropped by nearly 20%.
After conducting the study, Walsh obtained DNA and survival information for more than 15,000 men from the UK, Biobank, a huge health database. The information showed that men who had lost the Y chromosome in at least 40% of their white blood cells were 31% more likely to die from circulatory system diseases. Of the men with Y chromosome absences, many died due to cardiac conditions.
While the study seems like a huge breakthrough, the medical community has had differing views on it. On one hand John Parry, a human geneticist at the University of Cambridge says, “this is the best evidence to date.” Perry has led a different big study on the frequency of Y chromosome loss as well. Mitchell Machiela of the National Cancer Institute who wasn’t a part of the study also says the research provides “compelling evidence”.
On the other hand, cardiologist Nikoloas Frangogiannis of the Albert Einstein College of Medicine on the other hand says, “the fibrosis is fairly subtle,” and the heart weakening the mice suffered “is not that bad”. He still thinks the study is “very exciting” though.
Sources
https://www.science.org/content/article/men-lose-y-chromosomes-they-age-it-may-be-harming-their-hearts
https://www.franciscanhealth.org/community/blog/what-is-stiff-heart-syndrome
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3987984/#:~:text=Laboratory%20rats%20and%20mice%20provide,terms%20of%20anatomy%20and%20physiology.
The Y chromosome is one of two sex chromosomes; X and Y. Women have only two X chromosomes while men have both X and Y chromosomes. While scientists have long correlated the loss of Y chromosome to diseases and higher mortality rates, the evidence isn’t very conclusive.
The loss of Y chromosome isn’t 100% known but it has been attributed to one main cause. The Y chromosome carries less than a tenth of the X chromosome, carrying only 71 genes. Scientists theorize that because of this, the Y chromosome sometimes isn’t passed on when a cell divides.
Researchers have used blood samples as the primary form of analyzing Y chromosome absence. The Y chromosome has been found to be missing from white blood cells of 40% of 70-year-olds and 57% of 93-year-olds.
The study that molecular biologist Kenneth Walsh of the University of Virginia conducted was on mice, which are relatively anatomically and physiologically close to humans, as well as being easier to work with. After removing Y chromosomes from male mice, through blood transplants of bone marrow, the study found that mice lacking the Y chromosome had stiffer hearts. A stiff heart is when muscles and connective tissue around the heart thicken, causing shorter breath and fluid retention in the lungs and legs.
While Y chromosomes aren’t necessarily needed to survive, the study showed that without the Y chromosome in their bone marrow, the mice’s macrophages, a type of white blood cells, promoted the stiffening of the hearts. This stiffening of the hearts is also known as fibrosis which causes many circulatory issues. After the fibrosis, the contraction strength of the mice’s hearts dropped by nearly 20%.
After conducting the study, Walsh obtained DNA and survival information for more than 15,000 men from the UK, Biobank, a huge health database. The information showed that men who had lost the Y chromosome in at least 40% of their white blood cells were 31% more likely to die from circulatory system diseases. Of the men with Y chromosome absences, many died due to cardiac conditions.
While the study seems like a huge breakthrough, the medical community has had differing views on it. On one hand John Parry, a human geneticist at the University of Cambridge says, “this is the best evidence to date.” Perry has led a different big study on the frequency of Y chromosome loss as well. Mitchell Machiela of the National Cancer Institute who wasn’t a part of the study also says the research provides “compelling evidence”.
On the other hand, cardiologist Nikoloas Frangogiannis of the Albert Einstein College of Medicine on the other hand says, “the fibrosis is fairly subtle,” and the heart weakening the mice suffered “is not that bad”. He still thinks the study is “very exciting” though.
Sources
https://www.science.org/content/article/men-lose-y-chromosomes-they-age-it-may-be-harming-their-hearts
https://www.franciscanhealth.org/community/blog/what-is-stiff-heart-syndrome
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3987984/#:~:text=Laboratory%20rats%20and%20mice%20provide,terms%20of%20anatomy%20and%20physiology.