Boys who smoke in their early teens risk passing on harmful epigenetic changes in the genes of their future children without altering the DNA.
Experimental studies so far have suggested that tobacco exposure may impact respiratory health across generations via epigenetic changes transmitted specifically through male germ cells. However, studies in humans are limited, so researchers in the UK and Norway wanted to identify epigenetic marks in offspring associated with the father’s preconception for smoking.
People whose fathers smoked regular or electronic cigarettes (e-cigs) in their early teens had epigenetic markers associated with asthma, obesity, and poor lung function. Biomarkers linked with smoking by males even long before they became fathers were different from those associated with smoking by mothers.
“We must act now to stop teenage vaping,” scientists at the University of Southampton and the University of Bergen warned.
They have just published their study in the journal Clinical Epigenetics under the title “Fathers’ Preconception Smoking and Offspring DNA Methylation.” It is the first human study to reveal the biological mechanism behind the impact of fathers’ early teenage smoking on their children.
The team investigated the epigenetic profiles of 875 individuals aged seven to 50 and the smoking behaviors of their fathers. They found epigenetic changes at 19 sites mapped to 14 genes in the children of fathers who smoked before the age of 15. These changes in the way DNA is packaged in cells (methylation) regulate gene expression (switching them on and off) and are associated with asthma, obesity, and wheezing.
“Our studies in large international studies have shown that the health of future generations depends on the actions and decisions made by young people today – long before they are parents – in particular for boys in early puberty and mothers/grandmothers both pre-pregnancy and during pregnancy,” said Prof. Cecilie Svanes of the Norwegian university who was among the leading researchers. “It is really exciting that we have now been able to identify a mechanism that explains our observations in the cohorts.”
“Changes in epigenetic markers were much more pronounced in children whose fathers started smoking during puberty than those whose fathers had started smoking at any time before conception,” says co-lead author of the paper Dr. Negusse Kitaba, a research fellow at the British university. “Early puberty may represent a critical window of physiological changes in boys; this is when the stem cells are being established which will make sperm for the rest of their lives.”
What changes did it make for others to be smokers?
The team also compared the paternal preconception smoking profiles with people who themselves smoked and those whose mothers smoked before conception.
“Interestingly, we found that 16 of the 19 markers associated with fathers’ teenage smoking had not previously been linked to maternal or personal smoking,” said Dr. Gerd Toril Mørkve Knudsen from the University of Bergen and co-lead author of the study. “This suggests these new methylation biomarkers may be unique to children whose fathers have been exposed to smoking in early puberty.”
The number of young people smoking has fallen in the UK in recent years. But a co-author, Southhampton’s allergy and respiratory genetics Prof. John Holloway, is worried about children taking up vaping.
“Some animal studies suggest that nicotine may be the substance in cigarette smoke that is driving epigenetic changes in offspring,” he said, “so it’s deeply worrying that teenagers today, especially teenage boys, are now being exposed to very high levels of nicotine through vaping.”
The evidence from the new study came from people whose fathers smoked as teenagers in the 60s and 70s, when smoking tobacco was much more common.
“We can’t definitely be sure vaping will have similar effects across generations, but we shouldn’t wait a couple of generations to prove what impact teenage vaping might have. We need to act now,” Holloway said. “Our new findings have significant implications for public health. They suggest a failure to address harmful exposures in young teenagers today could damage the respiratory health of future generations.”