Genetic mutation risk increases with father-age

Genetic mutation risk increases with the age of the father

23/08/2012

The older a father is at the time of conception, the higher the risk of mutations in the genome of the child. That's what Icelandic and Danish scientists found out. The genetic modification could increase the likelihood of developing diseases such as autism or schizophrenia.

A 40-year-old father transfers an average of 65 mutations to his child
Like the scientists around Kári Stefánsson from the pharmaceutical company Decode Genetics in Reykjavík in the specialist magazine „Nature“ report, the number of changes in the genotype of the child with each year of life of the father at the time of conception increases. „Already a 20-year-old father transfers about 25 new mutations to his child on average, a 40-year-old father about 65 ", the researchers write „de novo mutations, "regardless of their age, this type of mutation is not passed on for several generations, but first shows up to a family member. „De novo mutations "either occur in a newly fertilized egg or are already present in the egg or sperm cells before fertilization.

The cause of the difference between fathers and mothers lies in the strongly diverging development of sperm and egg cells. While the spermatozoa are continuously formed in males and undergo numerous divisions and frequent mutations, in females, almost all oocytes are already created in the baby's age, with their maturation taking place sequentially. For the researchers, the results of the investigation were therefore not surprising. „But the strong linear effect of two additional mutations per year is impressive. After all, that's equivalent to doubling every 16.5 years, "they write.

Risk of autism and schizophrenia may be increased by mutations
The researchers further report that the increased transmission of mutations with increasing age of the father could potentially affect the risk of autism and schizophrenia. This has already been pointed out by a study published in April. „The older we are as fathers, the more likely it is that we pass on our mutations“, explains Stefánsson. „And the more mutations we pass on, the more likely it is that one is harmful.“ However, the researchers point out that although their study does not prove that older fathers are more likely than younger fathers to associate with disease or pass on other damaging genes, that is the logical conclusion, as Stefánsson and other geneticists say.

Evolutionary geneticist Alexey Kondrashov of the University of Michigan wrote in his commentary on the investigation: „If the effect of the paternal age on the rate of "de novo mutations" leads to significant health problems in the children of older fathers, then it could be a wise decision as a young man to collect his sperm and freeze it for later. "

The researchers examined a total of 78 parent-child groups, some of which included the grandchildren. They analyzed the genome of 219 people and looked in the child for mutations that did not occur in any of the two parents and thus must have originated spontaneously in the egg or sperm cell or the embryo.

They calculated that an Icelandic child born in 2011 had 70 new mutations in hereditary material, whereas in 1980's children there were only 60 mutations. „The average age of paternity has increased from 28 to 33 years during this period“, it says in the trade magazine. (Ag)

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Image: Annamartha