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zoom RSS 高齢の父親ほど孫が自閉症になるリスクが増大する

<<   作成日時 : 2013/03/24 23:11   >>

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 国際的な研究により、高齢の父親ほど孫が自閉症になるリスクが増大するという。
 これまでの研究により、高齢の父親は自閉症児を持つリスクが高いとされている。
"サイレント変異"と呼ばれ、他の遺伝子や環境要因が相互に働いて、子どもには影響しないが孫の世代に影響を及ぼす。
 50才以上の時に生まれた娘が20〜24才で子どもを産んだ場合、孫が自閉症である可能性は1.79倍になるという。50才以上の時に生まれた息子の子どもの場合は自閉症の可能性は1.67倍になる。

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21 March 2013 Last updated at 02:15 GMT
Grandparents 'may relay autism risk to grandchildren'
By Smitha Mundasad
Health reporter, BBC News
http://www.bbc.co.uk/news/health-21857403

画像The risk of developing autism may be passed on through - and not just to - future generations, researchers say.

The international study suggests older fathers are more likely to have grandchildren with autism than their younger counterparts.

The mechanism is unclear but it is thought they may transmit "silent mutations" to their grandchildren.

But experts have urged caution, stressing autism is the result of many different factors.

The study, looking at almost 6,000 people with the condition, is published in the journal Jama Psychiatry.

According to the National Autistic Society, more than one in every 100 people in the UK have the condition.

Previous studies suggested older fathers may be at greater risk of having children with autism than younger dads.

But the team of UK, Swedish and Australian researchers say this is one of the first pieces of evidence to show the risk can be passed on through - rather than just straight to - future generations.

Continue reading the main story

Start Quote

We can't put exact figures on this risk yet. But most children born to older fathers and grandfathers grow up fine”

Dr Avi Reichenberg
Co-author of study
The "silent mutations" - changes in genetic material - are likely to have no obvious impact on older fathers' own children, but they may build up through subsequent generations, or interact with other genes and environmental factors, to increase the chance of their grandchildren developing the condition, the researchers say.

Using national databases from Sweden they studied almost 6,000 people diagnosed with the condition and more than 30,000 without, tracking their parents' and grandparents' ages.

They found men who had a daughter when aged 50 or older were 1.79 times more likely to have a grandchild with autism, compared to men who fathered children when aged between 20-24.

And those who had a son when 50 years of age or older were 1.67 times more likely to have a grandchild with the condition.

'Complex causes'
But they say this study should not discourage older people from having children as though the risk is increased, it still remains small.

Co-author of the study, Dr Avi Reichenberg from King's College Institute of Psychiatry, told the BBC: "It is about choices. If you choose to have a child at an old age there might be consequences. This is something everyone should consider.

Continue reading the main story
Autism


People with autism usually have difficulties with social communication, social interaction and social imagination
It is a spectrum condition meaning while all people with autism share certain difficulties, the condition affects them differently
There are more than 500,000 people with autism in the UK - that's one in every 100
There is no cure, but there are a range of interventions available
Source: NHS Choices

"Unfortunately we can't put exact figures on this risk yet. But most children born with older fathers and grandfathers grow up fine.

"And as scientists this type of information helps open doors to understanding more about the condition."

Caroline Hattersley, of The National Autistic Society, said: "While this research is useful in aiding our understanding of autism's complex causes, it should be treated with caution.

"Autism is thought to be the result of many different underlying physical and genetic factors.

"The study is not definitive, as we know that many people who had children at a young age also have grandchildren with the condition. We therefore urge parents and those thinking of starting a family not to be concerned about the findings."

Dr Terry Brugha, professor of psychiatry at the University of Leicester who was not involved in the study, said: "This is a solid piece of work and the findings are plausible. But as a grandparent or parent-to-be this is not something to be overly concerned about.

"We are at the early stages of research and this study gives us a slightly deeper understanding of what is going on in the background."

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Autism Risk Across Generations
A Population-Based Study of Advancing Grandpaternal and Paternal Age
Emma M. Frans, MSc; Sven Sandin, MSc; Abraham Reichenberg, PhD; Niklas Langstrom, MD, PhD; Paul Lichtenstein, PhD; John J. McGrath, MD, PhD; Christina M. Hultman, PhD
JAMA Psychiatry. 2013;():1-6. doi:10.1001/jamapsychiatry.2013.1180.
Published online March 20, 2013

Importance Advancing paternal age has been linked to autism.

Objective To further expand knowledge about the association between paternal age and autism by studying the effect of grandfathers' age on childhood autism.

Design Population-based, multigenerational, case-control study.

Setting Nationwide multigeneration and patient registers in Sweden.

Participants We conducted a study of individuals born in Sweden since 1932. Parental age at birth was obtained for more than 90% of the cohort. Grandparental age at the time of birth of the parent was obtained for a smaller subset (5936 cases and 30 923 controls).

Main Outcome and Measure International Classification of Diseases diagnosis of childhood autism in the patient registry.

Results A statistically significant monotonic association was found between advancing grandpaternal age at the time of birth of the parent and risk of autism in grandchildren. Men who had fathered a daughter when they were 50 years or older were 1.79 times (95% CI, 1.35-2.37; P < .001) more likely to have a grandchild with autism, and men who had fathered a son when they were 50 years or older were 1.67 times (95% CI, 1.35-2.37; P < .001) more likely to have a grandchild with autism, compared with men who had fathered children when they were 20 to 24 years old, after controlling for birth year and sex of the child, age of the spouse, family history of psychiatric disorders, highest family educational level, and residential county. A statistically significant monotonic association was also found between advancing paternal age and risk of autism in the offspring. Sensitivity analyses indicated that these findings were not the result of bias due to missing data on grandparental age.

Conclusions and Relevance Advanced grandparental age was associated with increased risk of autism, suggesting that risk of autism could develop over generations. The results are consistent with mutations and/or epigenetic alterations associated with advancing paternal age.

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