A new study found that older men can carry more random genetic mutations that can increase the risk for autism or schizophrenia in a child.
The study, led by Augustine Kong at deCODE Genetics in Iceland found that a father’s age at conception can be responsible for 97 percent of the new, or de novo mutations in his child.
In recent decades, the diagnosis of autism has risen to a rate of 1 in 88 children in the United States.
Previous studies tied the disorders to the advanced age of the mother. Although older mothers are likely to have children with chromosomal abnormalities such as Down Syndrome, the father’s age is primarily responsible for the genetic risk of autism and schizophrenia.
“Our data indicate there is probably much more reason to be concerned with the age of the father, said Dr. Kari Stefansson, CEO of deCODE and senior author of the study.
De novo mutations are sporadic changes in the DNA that occur in the egg or sperm during conception. Most people are born with these types of DNA changes which are harmless. However, some of the mutations have been connected to the risk of autism and older fathers.
Researchers found that a 20-year-old man transfers an average of 25 genetic mutations to his child while a 40-year-old man passes on 65. As the father gets older, each year adds two mutations in his child’s DNA. Errors can occur among the billions of cells replicating when the genome is copied.
Study authors also found that fathers today are deciding to have children at a much older age.
“Collecting the sperm of young adult men and cold-storing it for later use could be a wise individual decision,” said Alexey Kondrashov of the University of Michigan.
Some mutation experts believe that the age of the father is not necessarily the primary factor.
“The observed effect is a significant one, but not one necessarily to cause great worry among prospective older fathers,” said Darren Griffin, a professor of genetics at University of Kent.
“There are three billion of letters in the DNA code of humans and the numbers of mutations detected in this study are in the dozens…and not realistically likely to deter more mature fathers from having children.”