Older men are more likely than younger ones to have children with autism or schizophrenia, and a new genetic study points to why: compared with younger dads, older fathers pass on significantly more random genetic mutations to their offspring that increase the risk for these conditions.
And when compared to the genetic contributions of the mother, older fathers are responsible for nearly all of a child’s random genetic mutations: a father’s age at conception may account for 97% of the new, or de novo, mutations found in his offspring, according to the new study led by Augustine Kong at deCODE Genetics in Iceland.
The findings may partly explain the rise in autism diagnoses in recent decades — the rate has reached 1 in 88 children in the U.S. — and they shore up previous studies finding that children born to older dads are more likely to have developmental and psychiatric disorders. The study also counters the common assumption that it is a mother’s advanced age that contributes to these problems. While older mothers are more likely to have children with chromosomal abnormalities, such as Down syndrome, the new study finds that it is the father’s age that accounts for virtually all of the genetic risk of autism and schizophrenia attributable to de novo mutations.
“Our data indicate there is probably much more reason to be concerned with the age of the father,” says Dr. Kari Stefansson, CEO of deCODE and senior author of the paper, published in Nature.
(MORE: Autism Studies Confirm Genetic Risk for Older Dads)
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