A survey of 24,097 parents and their children show that the children of teenage fathers have unexpectedly high levels of DNA mutations. Teenage fathers evidently have sperm cells with about 6 times more DNA mutations than the egg cells of teenage girls. And it seems their sperm cells have about 30% more mutations than those of 20-year-old men. This could explain why children from teenage parents have a higher risk for autism, schizophrenia, low birth weight, spina bifida, and other defects. It should be noted though that only 1.5 percent of babies on average have abnormalities, hence an increase by 30 percent to 2 percent of births is still a small percentage.
The reason for the excessive DNA mutations in teenage fathers’ children is not yet clear. 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. The type of DNA analysed in this survey is repetitive DNA known as microsatellites, which the authors have used to track the number of times that a cell divides. It will now be important to investigate whether other types of DNA mutations are also increased in the children of teenage fathers.
Research: Elevated germline mutation rate in teenage fathers, Peter Forster, Carsten Hohoff, Bettina Dunkelmann, Marianne Schürenkamp, Heidi Pfeiffer, Franz Neuhuber, Bernd Brinkmann, Proceedings of the Royal Society B, DOI: 10.1098/rspb.2014.2898, published 18 February 2015.
Source: The Royal Society