Children of older dads are more likely to develop diseases such as schizophrenia and autism than those of younger fathers, new research suggests.
Older men pass on more new DNA mutations - de novo mutations - to their kids than younger dads, putting their children at a higher risk for developmental issues, according to a study published Wednesday in the scientific journal Nature.
The findings - the first to quantify just how many more new hereditary mutations older dads pass on (about two for each added year of age) - challenge previous assumptions that maternal age plays a major factor in whether a child will exhibit developmental problems, the Wall Street Journal reported.
Maternal age has proven to be a significant cause of chromosomal problems in children, such as Down's syndrome.
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"The only important thing when it came to explaining the mutations was the age of the father," study author Kari Stefansson told Bloomberg News. "There's very little else to be accounted for. That's a stunning observation."
Scientists at deCode Genetics Inc., in Reykjavick, Iceland examined the DNA of 78 Icelandic families and found that a 20-year-old father passes on an average of 25 new mutations while a 40-year-old dad passes on 65.
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Mothers were found to transmit approximately 15 new mutations no matter what their age, according to an accompanying editorial penned by Alexey Kondrashov, a professor of evolutionary biology at the University of Michigan in Ann Arbor.
Men likely transmit more mutations than women because sperm divide many more times than eggs.
Kondrashov wrote that it "could be a wise individual decision" for dads-to-be to collect their sperm when they're young and use it when they're older given the study's results.
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The findings also may explain why the U.S. autism rate has continued to rise over the years.
Nearly one in 88 U.S. children had autism or a similar disorder in 2008 - a 23 percent jump from 2006, according to the U.S. Centers for Disease Control and Prevention.
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"It's very likely that the rise in the mean age of fathers has made some contribution to the apparent epidemic of autism in our society," Stefansson, the chief executive officer of deCode Genetics, told the Wall Street Journal.
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