Posted on 07/19/2022 10:49:48 AM PDT by Red Badger
Study in mice is first to directly test health effects of losing male chromosome
Computer generated X and Y chromosomes
The Y (right) may be the runt of the chromosomes, but losing it may lead to heart failure and death. NATHAN DEVERY/SCIENCE SOURCE
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As men get older, they don’t just lose their hair, muscle tone, and knee cartilage. They also start to lose Y chromosomes from their cells. Scientists have linked this vanishing to a long list of diseases and a higher risk of death, but the evidence has been circumstantial. Now, researchers report that when they removed the Y chromosome from male mice, the animals died earlier than their Y-carrying counterparts, likely because their hearts became stiffer.
“This is the best evidence to date” that losing the Y chromosome is detrimental to health, says John Perry, a human geneticist at the University of Cambridge. Perry led one of the biggest studies on the frequency of Y chromosome loss in men, but wasn’t connected to the new research.
Despite its macho reputation, the Y chromosome is a pipsqueak, carrying a mere 71 genes—less than one-tenth as many as the X chromosome. That may be why the chromosome sometimes doesn’t get passed on when a cell divides. Analyzing blood samples is the easiest way to detect loss of Y, and researchers have found the chromosome is missing from at least some white blood cells in about 40% of 70-year-olds and 57% of 93-year-olds. In some older men, more than 80% of the cells can be short a Y chromosome.
Cells can survive and reproduce without a Y, but men lacking the chromosome in some of their cells are more likely to suffer from heart disease, cancer, Alzheimer’s disease, and other aging-related ailments. Moreover, the condition could be a reason why men die on average about 5 years earlier than women in the United States, says molecular biologist Kenneth Walsh of the University of Virginia.
To test whether removing the Y chromosome harms health, Walsh and colleagues performed bone marrow transplants on 38 mice. They used the CRISPR-Cas9 gene-editing tool to delete the Y chromosome from mouse bone marrow cells and then inserted the altered cells into young male mice whose bone marrow had been removed. The swap didn’t banish the Y chromosome from the recipients, but it culled the chromosome from 49% to 81% of white blood cells—about the same percentage as in many humans with Y-chromosome loss. The 37 control mice for this experiment also received bone marrow transplants but retained the Y chromosome.
For nearly 2 years, the researchers followed both groups of animals. The Y-lacking rodents were more likely to die during this period—only about 40% of these mice survived for 600 days after the transplants, versus about 60% of the control rodents.
Mice that lost their Y chromosome also had weaker hearts. After about 15 months, the heart’s contraction strength had declined by close to 20%. In addition, the buildup of tough connective tissue, a process called fibrosis, surged in the hearts of mice missing the Y chromosome. This accumulation stiffens the heart and impairs its ability to pump blood.
The bone marrow transplants the researchers performed on the mice did not eliminate the Y chromosome from heart muscle cells. But the white blood cells called macrophages, which are born in the bone marrow, slip into the heart. The scientists found that many of the macrophages from mice lacking the Y chromosome began to promote fibrosis, stimulating other cells in the heart to spin more connective tissue.
Something similar may be going on in humans. Walsh and colleagues obtained DNA and survival information for more than 15,000 men from the UK Biobank, a huge health database. The team determined that men who had lost the Y chromosome from at least 40% of their white blood cells were 31% more likely to die from circulatory system diseases than those in which the chromosome was more abundant. When the scientists broke down the causes of death that correlated with the Y chromosome’s absence, they identified several cardiac conditions, including heart failure.
Losing the Y chromosome spurs fibrosis in the heart, resulting in heart failure and an earlier death, the team concludes today in Science. Researchers have long downplayed the Y chromosome’s health impact because it sports so few genes, Walsh says, but the evidence suggests shedding it “leads to a staggering amount of years of life lost.”
Genetic epidemiologist Mitchell Machiela of the National Cancer Institute, who also wasn’t connected to the study, says the research provides “compelling evidence.” The discovery that macrophages in the Y-lacking mice change their “personality” and begin to foster fibrosis makes sense, adds collagen biologist Amy Bradshaw of the Medical University of South Carolina. This switch “is central to a lot of the fibrosis we see in the heart.”
However, cardiologist Nikolaos Frangogiannis of the Albert Einstein College of Medicine cautions that the results do not confirm that increased fibrosis is killing the mice. In the animals missing the Y chromosome, “the fibrosis is fairly subtle,” he says. Moreover, the heart weakening the rodents suffered “is not that bad” and would not be fatal. The mice may be dying from some other heart-related cause. Still, he says, the study is “very exciting” and “could have a major impact on the way we see heart failure.”
doi: 10.1126/science.add9504
“As men get older, they don’t just lose their hair, muscle tone, and knee cartilage.”
Wait a sec, there! The author left off the most important thing that men lose as they age. I’ll hazard a guess and say this was written by a woman. ;>)
HOLY CRAP! This means as I grow older my chances of death increase? Why didn’t anybody tell me this?!
I wonder i this includes a suggestion that as men age they get tested for this reduction in the Y-Chromosome; and what if anything, as men age, can be done about it? “Stem cells”???
Y?
Where did I put that?
Car keys too. Or so I’ve heard.
Men Lose Y Chromosome to Libtardism 🤪
Men?
This author is transphobic!
Yeah, but, the article says their HEART gets stiffer.
Something to lean on in my old age?
Seems strange one would los the Y chromosome as one ages. Lad tests show that I have very high total testosterone for someone my age, does that mean mine are still intact?
As long as I can get the wrinkles out, I’m good.
I burned 82 candles this year, and 2 years ago I added light weight lifting to my fast walk on treadmill routine. Believe it or not, I have gained NEW muscles in upper body. So old men do not need to lose muscle tone. They just need to strain the muscles with exercise.
5 years ago I twisted by knee on a sand filled walking track in my condo complex. The knee was swollen quite a bit and was painful to walk. Doctor sent me for X-rays. Looking at the X-ray results she said I had bone of bone situation in knee. She gave me a shot (I think cortisone?) and with rest for 2+ weeks, the swelling went down, but knee was still painful to walk. My cousin talked me out of knee surgery based on his experience with both knees replaced and one knee still has lot of pain after 5 years. So I took up walking on treadmill. Slowly I increased time and speed of the walk. after a year of this, another miracle, I have no longer any pain in the knee!
Sadly there is no exercise available to cure deteriorating performance by the gonads. But regular physical exercise has many other side benefits. For one thing, I have not caught cold or flu or covid or any respiratory disease for many years. And secondly, my heart seems to be in better shape with no more chest pains after eating a good steak or prime rib. Finally I am also convinced regular exercise is delaying the inevitable onset of dementia.
Just the right ones..........
“Runt of the chromosomes.” “pipsqueak”
“macho reputation”
I’ll bet they wouldn’t say that about the female chromosome. That language is unworthy of a “science” publication.
The article talks about MEN and heart conditions. The “research” was conducted on mice. 75 in all. No male humans took part in the “research.”
But but but... I thought there was no definition of male or female! I thought male was the same as female! I thought you could pass from one to the other by kicking your heels together and wishing! The article unmistakably shows that the distinction male/female is determined by the presence or absence of the Y chromosome! What will the trans hysterics say to that?
So that’s what happened to Richard Levine! He lost his Y chromosome.
This might account for some men taking on a smoothe, androgynous appearance as they age.
Bruce Jenner was unavailable for comment.........................
LOL...so nature is in perfect balance: less stiff and more stiff.
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