Do men have a biological clock? Should they be haunted by its tick, as women have long been? Should they at least be aware that it exists?
A study released today in the journal Nature (and first reported by Benedict Carey in the New York Times) is the latest in a series of data confirming that the age of a father at conception can affect the mental health of his child.
The study looked specifically at autism and schizophrenia, the two conditions that have most often been linked to genetic changes in older fathers. While not a huge risk for each individual -- the chance of a man age 40 or older having a child with either mutation is about 2 percent -- collectively it could explain the jump in autism diagnoses in recent decades. Experts interviewed by the Times suggested that such mutations may be shown to be responsible for 15 to 30 percent of all cases of autism.
What is new about this data is the specificity with which it tracks the increased likelihood that sperm will mutate over time. As Carey writes:
The research team found that the average child born to a 20-year-old father had 25 random mutations that could be traced to paternal genetic material. The number increased steadily by two mutations a year, reaching 65 mutations for offspring of 40-year-old men. The average number of mutations coming from the mother's side was 15, no matter her age, the study found.
So, what will be the effect of this kind of knowledge? In an essay in the New York Times Magazine back in 2009, I asked exactly that, looking at the already significant evidence that older fathers put children at risk (not just for autism and schizophrenia, but also bipolar disorder, lower IQ and even the odds of being conceived in the first place) and wondering whether these facts would make a dent in long-held cultural assumptions.
"The message to women," I mused, has always been "youare the direct cause of your baby's health" while the message to men was "You, too, could be Tony Randall." But I wondered:
If those underlying assumptions were to change, would all that follows from them change as well? A world in which each man heard his clock tick even a fraction as urgently as each woman could be a very different world indeed. All those silver-haired sex symbols, and balding sugar daddies, and average-Joe divorced guys who are on their second families because they can be while their exes are raising their first set of kids -- what if all of them became, in women's eyes, too darned old?
It certainly hasn't happened in the three years plus since I wrote that. I haven't heard of men racing to sperm banks to save samples for their future, the way young women are reported to be freezing their eggs. And while there is a growing acceptance of women dating men who are younger, I don't think that calculations about sperm health are the reason.
What will it take before men hear a tick tick in the night? Or is our view of age as a mother's problem too ingrained to shift?
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"From prior studies of shared autism in twins, scientists had estimated that 90 percent of autism risk was attributable to genes and only 10 percent to non-genetic environmental factors. But the new study — the largest ever of twins in which at least one in each pair has autism — shows almost the opposite: It found that genes account for 38 percent of autism risk, with environmental factors explaining the remaining 62 percent.
"It took me a bit by surprise that the heritability of autism was so much lower than previous studies calculated," said Joachim Hallmayer, MD, the first author of the new paper, which appears in the July 4 issue of Archives of General Psychiatry. "Our work suggests that the role of environmental factors has been underestimated." Hallmayer is an associate professor of psychiatry and behavioral sciences at Stanford. "
"Our research shows us that we need to be studying both genetic and environmental factors as well as how they interact with each other," Hallmayer said. "We need to explore areas of environmental risk that are shared by both twin individuals and impact the development of the child."
And what might the unknown environmental risk factors be?
"That's the multimillion dollar question," Hallmayer said. "I think a lot about it." Autism's manifestation in very young children points to something that happens in early life, potentially even during pregnancy, hesaid.
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So far genetics 10 - 15 % ...
"The study looked specifically at autism and schizophrenia, the two conditions that have most often been linked to genetic changes in older fathers. "
* Genetics have so far been identified in only some 10 - 15% of ASD all up.
"the chance of a man age 40 or older having a child with either mutation is about 2 percent"
* Influenza virus - "The latest research shows a 7 fold elevation of risk of schizophrenia following exposure in the first trimester of pregnancy."
* "We found that 20% of prenatally rubella-exposed subjects were diagnosed with adult schizophrenia, suggesting a 10 to 20-fold increase in risk."
http://schizophreniabulletin.oxfordjournals.org/content/32/2/200.full
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Autism Genome Project
"Despite genotyping over a million SNPs covering the genome, no single SNP shows significant association with ASD or selected phenotypes at a genome-wide level.
variance explained by these allele scores was small (Vm< 1%).
individual SNPs and their en masse effect on risk, as inferred from the allele-scoreresults, it is reasonable to conclude that common variants affect ASD risk but their individual effects are modest.
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Yes genetics from Dad will play a part in ASD , so will Mum, the prenatal environment , epilepsy , immune system dysfunction ,autoimmune disease, depression , inflammation , the gut , bacteria, the human biome, environmental chemicals toxins and viruses.
ASD does not follow one common pathway it is a complex and intricate disease with many complex and intricate relationships.
"it begins in the womb"
"the mother’s ... inflammatory response — seems at fault."
"especially in the mother"
"Gene variants associated with autoimmune disease — genes of the immune system — also increase the risk of autism, especially when they occur in the mother."
Not in the same way. A woman is born with all of the eggs she will ever have. As a woman gets older, the quality of the eggs can deteriorate. Also, the vast majority are lost by the age of 40. This can affect the genetic outcome of offspring and lead to mutations in the offspring (genetic errors introduced in the offspring).
However, sperm are created throughout the life of the male from the successive division of precursor cells. This increases the odds of division errors (mutation) with each successive split. In the above referenced study the researchers found that this does in fact cause fathers to pass along more mutations than mothers.
Nothing. But it's very easy to jump to trivially false conclusions when the main spearhead of the article is feministic and NOT scientific.
Having said that... I was never in favor of "grandparents parents". And the examples in my immediate circle of friends have proven me quite right about that... without ANY genetic testing.
W&N
Isn't this just another study funded by the feminist lobby in an attempt to "prove" something by using a preselected sample and no control group?
You have a very colored past, feminist "studies." Try the scientific method, it works.
I think it has more to do with looking back in the families ancestry and the genes, myself.
Give you an example: If older moms were 30% more likely to give their child aspirin and aspirin led to autism then you would see a correlation between older women and autistic children. But if you didn't look at aspirin, if that wasn't part of your data set then you would attribute the significance to the age of the mom. If older moms were more likely to own cats, have sandboxes, use mothballs, have gardens or own more smoke detectors AND any of these activities had an effect on autism you would not be able to uncover the underlying correlations unless they were part of your data set.
W&N
This is rates of autism per 1000 babies born 96-07 - is that what you were looking for or something more specific? A woman over 40 I believe is presently said to have a 4/1000 chance of having an autistic child.