Smoking causes epigenetic changes in the Y chromosome in men.

ychSmoking has been linked to one of the biggest early risk factors for developing cancer. Now a new study has emerged specifying that smoking can cause the the loss of the Y chromosome in blood cells affected by the frequency of smoking. Generally people have 46 chromosomes in their cells, and two of these are sex chromosomes. Females have two X chromosomes, whereas males have one X and one Y. It is believed that the Y chromosome contains around 50-60 genes that provide the body with instructions for creating protein.

Only men have the Y chromosome, which “may in part explain why men in general have a shorter life span than women, and why smoking is more dangerous for men,” said lead researcher Prof. Jan Dumanski, of Uppsala University in Sweden.

Previous research has demonstrated a sex difference in smoke related cancer cases with male smokers are more likely to develop cancer outside of the respiratory tract than female smokers. The current study explains the sex difference by establishing a genetic link between smoking and damage that only affects men.

‘We have previously in 2014 demonstrated an association between loss of the Y chromosome in blood and greater risk for cancer. We now tested if there were any lifestyle or clinical factors that could be linked to loss of the Y chromosome,” said Lars Forsberg, another of the researchers.

“Our results indicate that the Y chromosome has a role in tumor suppression, and they might explain why men get cancer more often than women,” said Prof. Dumanski, regarding the previous study published in Nature Genetics.

The Y chromosome loss was dose dependent based on the amount of smoking. Men who had quit smoking experienced the same level of Y chromosome loss as men who had never smoked.

“These results indicate that smoking can cause loss of the Y chromosome and that this process might be reversible. We found that the frequency of cells with loss of the Y chromosome was not different among ex-smokers compared to men who had never smoked.”


Smoking is associated with mosaic loss of chromosome Y, Jan Dumanski, et al., Science, published online 4 December 2014, abstract.,8&typ=pm&na=&lang=en

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