Young fathers are more likely to pass genetic flaws than men a decade older and children born to teenage fathers are at higher risk of birth defects, a Cambridge study has found. Until now, it was believed that DNA mutation increases with age and this would force “textbooks to be rewritten”.
The research done on 24,000 parents and their children found that sperm cells of teenagers had 30 per cent higher rates of DNA mutation compared with those of men a decade older. Dr Peter Forster, a Fellow of Murray Edwards College and the McDonald Institute at the University of Cambridge, who led the research, said it could explain why teenage boys are more likely to have children who suffer from conditions such as autism, schizophrenia and spina bifida.
“It appears that the male germ cells accumulate DNA errors unnoticed during childhood, or commit DNA errors at an especially high level at the onset of puberty”, explained Dr Peter Forster. “Possibly the DNA copying mechanism is particularly error-prone at the beginning of male puberty. Or sperm production in boys may undergo dozens more cell cycles, and therefore DNA copying errors, than has previously been suspected.”
According to the findings, the levels of DNA mutation carried by teenage boy in the sperm cells is similar to those of men in their late thirties and forties. However, scientists note that chance of having children with abnormalities remains low for fathers in their teens or forties, with an overall risk of around 2 per cent.
The research also found that the germ cells of adolescent boys have more than six times the rate of DNA mutations as the equivalent egg cells in adolescent girls – around 150 cell divisions by puberty compared to the 22 cell divisions. Previous research suggested that germ cells in both boys and girls have a similar number of cell divisions and would have similar rates of DNA mutation.