Wednesday, 25 November 2009

• Special Education...

  Autism research: Scientists find genetic variations linked to autism.
  
  Reports show problems with brain cell communication may be related to condition By Trine Tsouderos |Tribune reporter April 29, 2009

  Researchers have found genetic variations that are significantly more common in people with autism -- a discovery that may improve diagnosis and offers the promise of developing treatments for the frustratingly mysterious disorder.
  
  The findings, published in the journal Nature, compared the genomes of thousands of autistic people to those of thousands of people without the disorder -- a massive task that new technology only recently made possible. The genome is the complex system of DNA coding that builds and runs the human body.
  
  Autism was linked to a genetic variation in a portion of DNA that affects the way brain cells connect with one another. Scientists also reported a link between autism and small "mistakes" in another DNA segment involved with cell communication. Both reports add weight to the idea that autism is related to problems with the connections among brain cells. 
  

  
  "It is very exciting," said study leader Hakon Hakonarson, director of the Center for Applied Genomics at Children's Hospital of Philadelphia. "It opens up the opportunity someday for new interventions to fix the bad consequences this variant has on brain function and development."
  
  

  Marked by impaired language and ability to interact, autism affects 1 in 150 children in the U.S., the Centers for Disease Control and Prevention said.
  
  For years the medical community has known little about what causes autism and how to treat it. The lack of scientific knowledge has led to a proliferation of pseudoscientific explanations for the disorder, as well as unproven treatments that often are costly and sometimes unsafe.
  
  This is not the first time geneticists have found a link between autism and DNA. For years, they have known changes on a particular gene result in Fragile X Syndrome and can cause autistic symptoms. Scientists also have found extremely rare instances where a tiny bit of DNA was missing or there were too many copies of another bit -- differences that account for only a fraction of autism cases.
  
  By contrast, the new research is "a big step," said Tom Lehner, chief of the Genomics Research Branch at the National Institute of Mental Health. "It opens up biology. With biology, you can find drug targets. Understanding the molecular networks, this is the big importance of these findings."
  
  One of the studies released Tuesday found that 65 percent of autistic participants shared a genetic variation between cadherin 10 and cadherin 9, a region of the genome that controls cell-adhesion molecules in the brain. The figure for study participants without autism was 60 percent -- a statistically notable difference.
  
  Cell-adhesion molecules help brain cells connect, and autism researchers have long suspected that trouble in this area may be linked to autism.
  
  "If we could remove this variant from the population, just take it away ... as much as 15 percent of autism would disappear, which is highly significant," Hakonarson said.
  
  The second study suggested there is a link between autism and an excess of genetic material associated with ubiquitin, a protein involved with cell-adhesion molecules and brain cell connections.
  
  Laura Herzing, who researches autism and genetics at Children's Memorial Research Center at Northwestern University, said the ubiquitin findings dovetailed with her research.
  
  "It will directly affect what I am doing," she said. "Identification of pathways in this way lets us know that we should also be looking closely at other genes and proteins in those pathways as well."
  
  Scientists believe larger studies will find yet more genetic variations, but even then those factors will never completely explain autism.
  

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