Genetic mutation risk increases with the age of the father
The older a father is at the time a child is conceived, the higher the risk of mutations in the child's genome. Icelandic and Danish scientists found out. The genetic changes could increase the likelihood of diseases such as autism or schizophrenia.
A 40-year-old father transfers an average of 65 mutations to his child
As the scientists around Kári Stefánsson from the pharmaceutical company Decode Genetics in Reykjavík report in the journal "Nature", the number of changes in the genome of the child increases with each year of father's birth. "Already a 20-year-old father transfers an average of around 25 new mutations to his child, a 40-year-old father about 65", the researchers write. In contrast, only 15 so-called "de novo mutations" come from the mother, regardless of their age. This type of mutation is not passed on for several generations, but is first seen in a family member. "De novo mutations" either occur in a newly fertilized egg cell or are already present in the egg or sperm cells before fertilization.
The reason for the differences between fathers and mothers lies in the very different development of sperm and egg cells. While the sperm cells in men are continuously formed and experience numerous divisions and frequent mutations, in women almost all egg cells are already in their infancy, with their maturation taking place one after the other. The results of the investigation were therefore not surprising for the researchers. “But the strong linear effect of two additional mutations per year is impressive. After all, this corresponds to a doubling every 16.5 years, "they write.
Mutations may increase risk of autism and schizophrenia
The scientists also report that the increased spread of mutations as the father ages can potentially affect the risk of autism and schizophrenia. This was already pointed out by a study published in April. "The older we are as fathers, the more likely we are to pass on our mutations," explains Stefánsson. "And the more mutations we pass on, the more likely one is harmful." However, the researchers point out that their study does not show that older fathers are more likely than younger fathers to be linked to diseases or other harmful ones Passing on genes, however, is the logical conclusion, as Stefánsson and other geneticists say.
Evolutionary geneticist Alexey Kondrashov of the University of Michigan wrote in his comment on the study: "If the effect of paternal age on the rate of" de novo mutations "leads to significant health effects in the children of older fathers, it could be a wise decision to collect his sperm as a young man and freeze it for later. "
The researchers examined a total of 78 parent-child groups, some of which also included the grandchildren. They analyzed the genetic makeup of 219 people and looked for mutations in the child that did not occur in either of the two parents and thus must have arisen spontaneously in the egg or sperm cell or the embryo.
They have calculated that an Icelandic child born in 2011 will have 70 new mutations in the genome, compared to only 60 mutations in children born in 1980. "The average age of paternity has risen from 28 to 33 in this period," says the specialist magazine. (ag)
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