Father’s Age Linked to Autism
Risk of Genetic Mutations Tied to Autism May Increase With Each Year of Father’s Age
Paternal Age Accounts for a Lot continued...
“Ninety-seven percent of the difference is accounted for by the age of the father,” says Stefansson. “That was surprising to us because that means hardly anything else contributes to it.”
For example, Stefansson says, the environment may still affect the father’s mutation rate as an individual. But when you look at the population as a whole, 97% of the difference in the number of these potentially dangerous mutations is caused by paternal age.
Researchers say the next step is to better understand exactly how these de novo mutations contribute to various diseases.
While the mutations are currently associated with disorders like autism and schizophrenia, Stefansson says there could be a lot more.
Older Dads 'Mutational Bombs?'
Experts say the results underscore the fact that fathering children at an advanced age is not without risk.
“This is a breakthrough article,” says Harry Fisch, MD, clinical professor of urology and reproductive medicine at Weill Cornell Medical College of Cornell University. “It’s a real paradigm shift in terms of how we think about fertility and genetic abnormalities.”
“We used to think men can wait as long as they want to have children, but that’s not true,” he says. “Not all men can have children when they get older. If they do, they stand a higher risk of having a child with a genetic defect.”
Fisch says for women the age of 35 has become a benchmark for when the risk of having children with a genetic condition, such as Down syndrome, starts to escalate.
Now men have a reference point.
“For the first time, you can say there is a doubling of the mutation rate every 16 years,” says Fisch.
Stefansson even calls older men’s sperm “mutational bombs.”
Bottom line, Fisch says the study "is going to affect how we think about the causes of the increasing incidence of schizophrenia and autism, particularly autism.”
Previous studies have also shown that advanced paternal age is associated with a higher risk of miscarriage as well.
“As men are getting older, we are increasing the chance of genetic abnormalities in their children,” says Fisch. “It’s a public health concern.”