Teenage fathers often inherit mutated DNA

Study: Young fathers often give birth to mutated genetic material

02/18/2015

It has long been known that sperm quality gets worse in old age. However, a new study now shows that even young sperm do not necessarily have to be good. The researchers have found that the genetic makeup of teenage fathers is often burdened with mutations.

Young fathers pass on strained genetic material
According to a study, teenage fathers pass on mutant-burdened genetic material to their children more often than their 20- to 30-year-olds, the news agency dpa reports. The German-British researcher Peter Forster says that this could explain why children of pubescent fathers are even as high-risk as the offspring of 35-year-old GM producers, such as schizophrenia or open back (spina bifida). Forster and his colleagues from the Universities of Münster, Salzburg and Cambridge have studied 24,000 DNA samples of parents and their children from Europe, the Middle East and Africa. The results were in the journal „Royal Society Proceedings“ released.

Unclear how far-reaching the results are
However, it is disputed how far-reaching the results are. According to the human geneticist Jörg Epplen of the Ruhr-University Bochum, the findings are still no proof of the correlation between the mutations and a disease risk. According to the study authors so-called „mute“ Investigated genome parts that, according to the current state of science, have no significance for the characteristics or transmitted diseases of the offspring. On the other hand, the fact that especially old fathers can lay the foundations for future illnesses of the offspring when they are conceived is, on the other hand, scientifically proven. For example, a study by the Swedish Karolinska Institute in cooperation with the University of Indiana in the United States has shown that the risk of attention deficit hyperactivity disorder (ADHD) in offspring increases significantly if the fathers were 45 years or older at birth.

Sperm of pubescent boys are the exception
Science has so far assumed that a younger producer transmits hereditary diseases less often than an older one. This is because the reproductive stem cells of a male reproduce throughout his life and in this ongoing division process, each copy can result in new gene changes. Thus, with age, the burden of mutation in the reproductive cells of men increases. Sperm of pubescent boys, however, are an exception, as Forster and colleagues found. According to this, children of teenage fathers (12 to 19 years) in their genotype had about 30 percent more so-called de novo mutations than children of 20 to 30-year-old fathers. These are changes in the DNA that arise in the germ cells (eggs or sperm) and thus manifest themselves after fertilization in the children. „We think it is possible that the apparatus that produces sperm cells at the beginning of puberty is not yet fully adjusted and initially works with a high error rate“, Sun Forster.

Mutation burden remains the same for women throughout life
The team was surprised by another result. It turned out that the burden of mutation in the germ cells of boys at the beginning of reproductive ability is six times higher than in girls. According to the scientists, this could indicate that a male germ cell has far more dividing processes before fertility than genetic research has hitherto assumed. Forster explained: „According to the textbook, girls and boys have between 22 and 23 divisions before puberty. However, our findings could mean that male spermatozoa have already shared more than 100 times at puberty.“ According to the researchers, the burden of mutations in women stays at about the same level throughout life. This is because female embryos are born with a lifelong supply of oocytes that do not require further cell division and DNA copying. (Ad)