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Environment as important as genes in autism, study finds.
http://uk.reuters.com/article/2014/05/03/us-health-autism-idUKKBN0DJ0H020140503
Environment as important as genes in autism, study finds
BY KATE KELLAND
LONDON Sat May 3, 2014 9:41pm BST
(Reuters) - Environmental factors are more important than previously thought in leading to autism, as big a factor as genes, according to the largest analysis to date to look at how the brain disorder runs in families.
Sven Sandin, who worked on the study at King's College London and Sweden's Karolinska institute, said it was prompted "by a very basic question which parents often ask: 'If I have a child with autism, what is the risk my next child will too?'"
The findings, published in the Journal of the American Medical Association (JAMA), suggest heritability is only half the story, with the other 50 percent explained by environmental factors such as birth complications, socio-economic status, or parental health and lifestyle.
The study also found that children with a brother or sister with autism are 10 times more likely to develop the condition, three times if they have a half-brother or sister with autism, and twice as likely if they have a cousin with autism.
<>
Environment as important as genes in autism, study finds
BY KATE KELLAND
LONDON Sat May 3, 2014 9:41pm BST
(Reuters) - Environmental factors are more important than previously thought in leading to autism, as big a factor as genes, according to the largest analysis to date to look at how the brain disorder runs in families.
Sven Sandin, who worked on the study at King's College London and Sweden's Karolinska institute, said it was prompted "by a very basic question which parents often ask: 'If I have a child with autism, what is the risk my next child will too?'"
The findings, published in the Journal of the American Medical Association (JAMA), suggest heritability is only half the story, with the other 50 percent explained by environmental factors such as birth complications, socio-economic status, or parental health and lifestyle.
The study also found that children with a brother or sister with autism are 10 times more likely to develop the condition, three times if they have a half-brother or sister with autism, and twice as likely if they have a cousin with autism.
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10 replies
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SOURCE: http://www.mayoclinic.org/diseases-conditions/lung-cancer/basics/causes/con-20025531
Of course, not all smokers develop lung cancer and not all lung cancers are caused by smoking. Historical overview (WITHOUT FURTHER COMMENT), here:
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I beg to differ with your conclusion as evidenced in the case above and because autism researchers are already parsing out environmental causes.
Here, they "partialled them out" and found genes had nothing to do with it, it was all environment!
Good thing these scientists didn't say, "It's too complex, we're too stupid, let's go shopping!"
From last month: http://www.democraticunderground.com/101690675
http://medicalxpress.com/news/2014-04-scientists-unmask-piece-puzzle-inheritance.html
Scientists unmask a piece in the puzzle of how the inheritance of traumas is mediated
The phenomenon has long been known in psychology: traumatic experiences can induce behavioural disorders that are passed down from one generation to the next. It is only recently that scientists have begun to understand the physiological processes underlying hereditary trauma. "There are diseases such as bipolar disorder, that run in families but can't be traced back to a particular gene", explains Isabelle Mansuy, professor at ETH Zurich and the University of Zurich. With her research group at the Brain Research Institute of the University of Zurich, she has been studying the molecular processes involved in non-genetic inheritance of behavioural symptoms induced by traumatic experiences in early life.
<snip>
Small RNAs with a huge impact
The researchers studied the number and kind of microRNAs expressed by adult mice exposed to traumatic conditions in early life and compared them with non-traumatized mice. They discovered that traumatic stress alters the amount of several microRNAs in the blood, brain and sperm – while some microRNAs were produced in excess, others were lower than in the corresponding tissues or cells of control animals. These alterations resulted in misregulation of cellular processes normally controlled by these microRNAs.
After traumatic experiences, the mice behaved markedly differently: they partly lost their natural aversion to open spaces and bright light and had depressive-like behaviours. These behavioural symptoms were also transferred to the next generation via sperm, even though the offspring were not exposed to any traumatic stress themselves.
Even passed on to the third generation
The metabolism of the offspring of stressed mice was also impaired: their insulin and blood-sugar levels were lower than in the offspring of non-traumatized parents. "We were able to demonstrate for the first time that traumatic experiences affect metabolism in the long-term and that these changes are hereditary", says Mansuy. The effects on metabolism and behaviour even persisted in the third generation.
<snip>
Scientists unmask a piece in the puzzle of how the inheritance of traumas is mediated
The consequences of traumatic experiences can be passed on from one generation to the next.
Credit: Isabelle Mansuy / UZH / ETH Zurich
The phenomenon has long been known in psychology: traumatic experiences can induce behavioural disorders that are passed down from one generation to the next. It is only recently that scientists have begun to understand the physiological processes underlying hereditary trauma. "There are diseases such as bipolar disorder, that run in families but can't be traced back to a particular gene", explains Isabelle Mansuy, professor at ETH Zurich and the University of Zurich. With her research group at the Brain Research Institute of the University of Zurich, she has been studying the molecular processes involved in non-genetic inheritance of behavioural symptoms induced by traumatic experiences in early life.
<snip>
Small RNAs with a huge impact
The researchers studied the number and kind of microRNAs expressed by adult mice exposed to traumatic conditions in early life and compared them with non-traumatized mice. They discovered that traumatic stress alters the amount of several microRNAs in the blood, brain and sperm – while some microRNAs were produced in excess, others were lower than in the corresponding tissues or cells of control animals. These alterations resulted in misregulation of cellular processes normally controlled by these microRNAs.
After traumatic experiences, the mice behaved markedly differently: they partly lost their natural aversion to open spaces and bright light and had depressive-like behaviours. These behavioural symptoms were also transferred to the next generation via sperm, even though the offspring were not exposed to any traumatic stress themselves.
Even passed on to the third generation
The metabolism of the offspring of stressed mice was also impaired: their insulin and blood-sugar levels were lower than in the offspring of non-traumatized parents. "We were able to demonstrate for the first time that traumatic experiences affect metabolism in the long-term and that these changes are hereditary", says Mansuy. The effects on metabolism and behaviour even persisted in the third generation.
<snip>
http://jama.jamanetwork.com/article.aspx?articleid=1866100
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Original Investigation | May 7, 2014
The Familial Risk of Autism
Sven Sandin, MSc1,2; Paul Lichtenstein, PhD1; Ralf Kuja-Halkola, MSc1; Henrik Larsson, PhD1; Christina M. Hultman, PhD1; Abraham Reichenberg, PhD3,4,5
JAMA. 2014;311(17):1770-1777. doi:10.1001/jama.2014.4144.
ABSTRACT:
Importance Autism spectrum disorder (ASD) aggregates in families, but the individual risk and to what extent this is caused by genetic factors or shared or nonshared environmental factors remains unresolved.
Objective To provide estimates of familial aggregation and heritability of ASD.
Design, Setting, and Participants A population-based cohort including 2?049?973 Swedish children born 1982 through 2006. We identified 37?570 twin pairs, 2?642?064 full sibling pairs, 432?281 maternal and 445?531 paternal half sibling pairs, and 5?799?875 cousin pairs. Diagnoses of ASD to December 31, 2009 were ascertained.
<>
Conclusions and Relevance Among children born in Sweden, the individual risk of ASD and autistic disorder increased with increasing genetic relatedness. Heritability of ASD and autistic disorder were estimated to be approximately 50%. These findings may inform the counseling of families with affected children.
[img]
[/img]
Original Investigation | May 7, 2014
The Familial Risk of Autism
Sven Sandin, MSc1,2; Paul Lichtenstein, PhD1; Ralf Kuja-Halkola, MSc1; Henrik Larsson, PhD1; Christina M. Hultman, PhD1; Abraham Reichenberg, PhD3,4,5
JAMA. 2014;311(17):1770-1777. doi:10.1001/jama.2014.4144.
ABSTRACT:
Importance Autism spectrum disorder (ASD) aggregates in families, but the individual risk and to what extent this is caused by genetic factors or shared or nonshared environmental factors remains unresolved.
Objective To provide estimates of familial aggregation and heritability of ASD.
Design, Setting, and Participants A population-based cohort including 2?049?973 Swedish children born 1982 through 2006. We identified 37?570 twin pairs, 2?642?064 full sibling pairs, 432?281 maternal and 445?531 paternal half sibling pairs, and 5?799?875 cousin pairs. Diagnoses of ASD to December 31, 2009 were ascertained.
<>
Conclusions and Relevance Among children born in Sweden, the individual risk of ASD and autistic disorder increased with increasing genetic relatedness. Heritability of ASD and autistic disorder were estimated to be approximately 50%. These findings may inform the counseling of families with affected children.
