Smoking in teen boys leads to DNA damage in offspring

Specific epigenetic changes to the genomes of offspring have been linked to smoking by their fathers before the age of 15, a recent study across six countries showed.

It is thought these changes occurred due to excess methylation of DNA in stem cells found in the testes, that develop during puberty in a way that allows them to start producing sperm. Methylation refers to chemical modifications to DNA that can affect genetic transcription without altering the underlying genetic code. Results from the multi-centre cohort were published in Clinical Epigenetics.

Co-lead author Dr Negusse Kitaba, research fellow at the University of Southampton said: '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.'

The team from the University of Southampton and the University of Bergen, Norway, studied a two-generation cohort, comprising of 875 parent-offspring pairs aged between seven and 50 from different European locations and all participants were white.

While smoking before conception was linked to methylation at two sites in their offspring's genome, starting smoking before the age of 15 was linked to methylation at 19 sites on 14 genes in their offspring's genome. These changes were unique and separate from those associated with mothers' smoking during pregnancy or the smoking habits of the offspring.

The affected genes were primarily related to asthma, immune response regulation, and inflammatory responses. This supported previous findings that fathers' preconception smoking is associated with offspring health issues including asthma, obesity, and lung function problems.

While this study only assessed smoking, it also raised concerns about the impact of vaping and the generational impact this may have.

Dr Kitaba added: 'It's deeply worrying that teenagers today, especially teenage boys, are now being exposed to very high levels of nicotine through vaping. […] 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.'