Men who wait to have children until they are older, may be passing a gene mutation of Autism onto their grandchildren.
Avi Reichenberg of the Institute of Psychiatry at King’s College London, who co-led the study, said for the first time your father’s and grandfather’s lifestyle choices can affect you. “This doesn’t mean that you shouldn’t have children if your father was old when he had you, because whilst the risk is increased, it is still small,” he said.
Researchers at Sweden’s Karolinska Institute compared 5,936 people with autism, with 30,923 healthy controls. All of the participants had been born in Sweden after 1932. The researchers factored in the age of each person’s grandfathers, on both their paternal and maternal sides, and recorded any psychiatric diagnoses.
According to the study published in the Journal of the American Medical Association, compared to men who father children in their 20s, older men who had daughters were 1.79 times more likely to have autistic grandchildren, and older men who had sons were 1.67 times more likely to have them.
Autism disorders are caused by a combination of genetic and environmental factors and can range from severe mental retardation with a profound inability to communicate, to relatively mild symptoms combined with some high levels of function such as those seen in people with Asperger’s syndrome.
Although the study found a correlation between age in grandfathers and the odds for autism in children, it is only an observational trial, so it cannot prove cause and effect. Experts still say the risk for autism to any one family remains small.
“Although there was a statistically significant increase in the incidence of autism in families with older grandparents, it must be remembered that autism was still extremely infrequent even in families with the oldest grandparents,” said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Steven & Alexandra Cohen Children’s Medical Center of New York, in New Hyde Park. “Thus, older parents and grandparents should not be unduly worried.”
While it’s unknown why the link exists, researchers believe it has to do with the reproduction across genders.
“Men may play a significant role in autism development because their reproductive cells are more prone to mutation,” Frans said. “Although female reproductive cells divide and replicate 24 times, male reproductive cells continue reproducing throughout a man’s life. By the time he is 20, his reproductive cells have undergone 200 divisions. By the time he is 40, his reproductive cells have undergone 600 divisions.”
“Every time the cell divides, there’s a risk something goes wrong, which can result in manifestation of mutation,” Frans added.
“The age of your parents, you can’t control,” said Lori Warner, director of the HOPE Center for Autism at Beaumont Hospitals in Michigan. “It’s helpful for you to know that your dad was 60 when he had you, and you might be more at risk. But whether that should stop you from having a child at a certain age, that shouldn’t be a deciding factor.”
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