Despite the numerous health risks associated with smoking, a lot of people do it anyway. My mom was a smoker all throughout my childhood, so my brother and I grew up constantly hiding her cigarettes (and getting in major trouble for it) and generally thinking there was nothing grosser than cigarette smoke. In retrospect, I actually rather appreciate this, as cigarettes remain perhaps the one vice I’ve ever been tempted to try. And as if you need one more reason not to smoke, according to a recent study published in Science, the Y chromosome of men who smoke may disappear from their blood cells.
Men have one X chromosome and one Y chromosome; women have two X chromosomes. When cells divide, the chromosomes are all copied and sorted into the two new cells. Sometimes as this happens, chromosomes disappear, which typically causes the new cell to die. But cells can keep living without a Y chromosome. The disappearance of Y chromosomes has been documented for over 50 years, and tends to happen more in older men rather than younger ones. Researchers at Uppsala University in Sweden learned from a previous study that the loss of those Y chromosomes correlates with a higher risk of cancer for men.
The researchers wanted to find out why some men lose their Y chromosomes. This recent study found that men who smoke lose their Y chromosomes more often than those who don’t smoke, and the more a male smokes, the fewer remain in his blood. The study involved 6,000 men who gave blood samples and extensive histories about their habits, such as drinking, smoking, and exercise. The results indicate that it is common for men to lack Y chromosomes. Between 12.6-15.6% of 70-80 year olds in the student had lost the Y chromosome. In another group of men ages 48-93, only 7.5% were missing the chromosome, indicating the effects of age. Only 4.1% of the men under 70 lack a Y chromosome, and the only factor besides age that made an appreciable difference was smoking.
Among other things, the findings could explain why men who smoke have a higher risk of cancer than women who smoke. “The cells that lose the Y chromosome…don’t die, but we think that they would have a disrupted biological function,” says Lars Forsberg, study co-author. Specifically, immune cells that would normally help the body resist and fight cancer may not be as effective without the Y chromosome. One good bit of news is that the men who had given up smoking had the same levels of Y chromosome in their blood as those who never smoked, so the damage seems to be reversible, at least to some extent.
In their next study, the researchers plan to study different types of immune cells one by one to see which are most drastically affected by the loss.