SALT LAKE CITY — Older fathers are more likely to father a child with autism or schizophrenia, due to genetic mutations that increase with age, according to a new study published online Wednesday in the journal Nature.
Researchers examined 78 Icelandic families with children who had been diagnosed with autism or schizophrenia. They found that a 40-year-old passes 65 genetic mutations to his child, while a 20-year-old passes 25. Fathers transmitted two new mutations in their DNA each additional year, while mothers passed on 15 new mutations at every age.
The research corrected false assumptions that the risks lie in the older ages of women alone, the Los Angeles Times reported. "Although older mothers are more likely to have children with chromosomal disorders such as Down syndrome because of problems with older eggs, the study found that practically all of the novel mutations detected in children came from the father's sperm."
Experts said the finding might influence reproductive decisions, but was hardly reason to forgo fatherhood at an older age, The New York Times reported. There is a 2 percent overall risk to a man in his 40's or older, as well as other contributing factors that remain unknown.
The study found that as many as 20 to 30 percent of cases of autism diagnoses were linked to an older average age in fathers.
"The findings also give us insight into how our gene pool is changing, and what, in modern times, is driving the genetic diversity that is critical to the survival of our species," the Washington Post observed. "Every difference in our DNA that distinguishes each of us as individuals, or that separates Homo sapiens from other species, arguably got its start as a mutation. Some of these alterations in DNA occur by chance, during cell division, others are triggered by exposure to environmental factors, while still others are selected for when they happen to confer some survival advantage, such as an ability to ward off disease."
“The only important thing when it came to explaining the mutations was the age of the father,” study author Kari Stefansson, the chief executive officer of deCode Genetics, told the Bloomberg News. “There’s very little else to be accounted for. That’s a stunning observation.”
Rachel Lowry is a reporter intern for the Deseret News. She has lived in London and is an English graduate from Brigham Young University. Contact her at firstname.lastname@example.org or visit www.rachellowry.blogspot.com.