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Tero Toivanen

Genes implicated in twins' autism | The Autism News - 1 views

www.theautismnews.com/...nes-implicated-in-twins-autism

autism genetics genes twins research diagnoses environment

shared by Tero Toivanen on 05 Jan 10 - Cached
  • Researchers have known for years that when one identical twin has autism, the other is also likely to be diagnosed with it – evidence that autism likely has a genetic component.
  • Researchers at Kennedy Krieger Institute studied 277 pairs of twins and found that when one identical twin had the disorder, the other developed it 88 percent of the time; for fraternal twins, that figure was 31 percent.
  • Despite this progress in unlocking the mysteries of autism, scientists have simply confirmed that there are likely numerous genetic links to autism.
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  • Each discovery explains just a tiny fraction of autism’s causes. Researchers think the great majority – 90 percent – of autism cases have a genetic cause, but they’ve found fewer than 10 percent of the triggers.
  • researchers have found about 50 genes so far that might be tied to autism, which explain very few cases, he said.
  • Autism isn’t one disease; it’s too individual to locate just one genetic cause. It’s not like cystic fibrosis, a disorder for which researchers have identified one gene – and tests to diagnose it.
  • autism researchers envision that a wide variety of gene defects are responsible for the symptoms collectively known as autism spectrum disorders. The disabilities, different in each child, range from the mild Asperger syndrome to more severe impairments in social interaction and communication.
  • “It’s going to take some work before we understand the true causes of autism,” he said. “We need to make much more headway to ever have enough understanding so that patient management and therapies can be improved.”
  • None of the new findings explains why more children are being diagnosed with autism. Genes, said Goldstein, tell only part of the story.
  • “The idea is there is an environmental interaction with the genetic component,” he said.
  • Autism may be inherited to some degree, but even twin studies show that not all sets of identical twins have autism. And when they do, they don’t always have the same severity of the disorder
  • That connection between genes and the environment, called epigenetics, might explain these distinctions
  • Tero Toivanen on 05 Jan 10
     
    Researchers have known for years that when one identical twin has autism, the other is also likely to be diagnosed with it - evidence that autism likely has a genetic component.
Tero Toivanen

The Genetics of Autism (ActionBioscience) - 1 views

www.actionbioscience.org/...dougherty.html

autism genetics savant

shared by Tero Toivanen on 08 Apr 09 - Cached
  • Despite this relatively high frequency, scientists do not understand the mechanism of this serious developmental problem. What they have discovered is that autism is one of the most heritable mental disorders known. In other words, autism appears to be largely genetic in origin, and most autistic children inherit the disorder from their parents.
  • In the case of PKU, geneticists have determined that retardation is due to genetics (a mutated phenylalanine hydroxylase gene) and the environment (a phenylalanine-containing diet).
  • In the case of autism, the likelihood that the sibling of an affected child also would be affected is between three and six percent.
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  • Nonetheless, this incidence is about 100 times greater than the rate at which autism affects unrelated people in the population.
  • One study showed that the likelihood that the identical twin of an autistic child also would be autistic was 82 percent, whereas the equivalent rate for fraternal twins was only 10 percent.
  • With sophisticated statistical techniques and numerous twin studies, behavioral geneticists now believe that as much as 90 percent of the behavioral phenotype of autism is related to inherited genes.
  • Tero Toivanen on 08 Apr 09
     
    With sophisticated statistical techniques and numerous twin studies, behavioral geneticists now believe that as much as 90 percent of the behavioral phenotype of autism is related to inherited genes.
Tero Toivanen

Autism and early oxygen deprivation 2 | On the Brain by Dr. Mike Merzenich,Ph.D. - 0 views

merzenich.positscience.com/?p=248

autism oxygen deprivation placenta Amish Somalia umbilical cord

shared by Tero Toivanen on 25 Jun 09 - Cached
  • Fraternal twins typically have different placentas, whereas identical twins share a placenta but have different cords. The blood supply, and pre-clamping susceptibility to anoxia, would surely be different.
  • As for the idea that one could statistically detect whether cord clamping is the problem, we can! Amish people do not clamp the cord until placental delivery, and they have no autism rate. The same is true in Somalia, but Somalian immigrants to westernized medical countries have high rates. Try to systematically find out autism rates and immediate cord clamping rates, on a country by country, or region by region basis. It is a task someone should get on immediately, but it will take a lot of effort.
  • An interesting discussion of the “Amish anomaly” re autism incidence has been provided by Dan Olmsted, who went to Amish Country to find the 150 or so individuals there who could be expected to be severely autistic. They aren’t there. He seems pre-disposed to believe that the difference lies with their non-vaccination. Many studies now show that this is unlikely. As David Blake points out, there is another difference in this population: In Amish birthing, by tradition, the cord is not clamped prior to placenta delivery.
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  • The picture with autism in Somali children is a little murkier. It turns out that the incidence of autism is very high in children of Somali origin who were born in the US (several times higher than normal), while it appears to be very low in Somali children born in their native country. Again, vaccination has been identified as the likely cause by Somali parents and by many observers — but again, clamping follows placental delivery in Somalia, while the cord has been clamped without delay as a general practice in Minnesota, where a high incidence of autism in these children of Somali immigrants was first discovered.
  • Tero Toivanen on 25 Jun 09
     
    Comment about the hypothesis that early umbilical cord clamping might contribute to the risk of origin of autism.
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