01 June 2007

Smoking damages sperm

Smoking may cause mutations to a man’s sperm that can lead to genetic problems in his offspring.

It has long been scientifically established that smoking causes cancer, but new research suggests that children could inherit genetic damage from a father who smokes.

In an experiment with mice, Canadian researchers have demonstrated that smoking can cause changes in the DNA sequence of sperm cells, alterations that could potentially be inherited by offspring. The results of their study are published in the 1 June issue of the journal Cancer Research.

“Here we are looking at male germline mutations, which are mutations in the DNA of sperm. If inherited, these mutations persist as irreversible changes in the genetic composition of offspring,” said Carole Yauk, Ph.D., lead author of the study and research scientist in the Mutagenesis Section of Health Canada’s Environmental and Occupational Toxicology Division.

Dads harming their kids?
“We have known that mothers who smoke can harm their foetuses, and here we show evidence that fathers can potentially damage offspring long before they may even meet their future mate.”

Males, whether they are mice or men, generate a constant supply of new sperm from self-renewing spermatogonial stem cells.

The researchers studied the spermatogonial stem cells of mature mice that had been exposed to cigarette smoke for either six or 12 weeks. They looked for alterations in a specific stretch of repeated portions of DNA, called Ms6-hm, which does not contain any known genes. The “smoking” mice were exposed to two cigarettes per day, being the equivalent (based on blood levels of tobacco by-products) of an average human smoker.

They found that the rate of Ms6-hm mutations in the "smoking" mice were 1.4 times higher than that of "non-smoking mice" at six weeks, and 1.7 times that of "non-smoking" mice at 12 weeks. “This suggests that damage is related to the duration of exposure, so the longer you smoke, the more mutations accumulate and the more likely a potential effect may arise in the offspring,” Yauk said. – (EurekAlert)

Read more:
Stop smoking Centre
Top 5 smoking myths

June 2007


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