Big Autism Study Reveals New Genetic Clues, but Also Baffling Complexity

By Joseph Calamia | June 9, 2010 5:41 pm

DNAResearchers have published the largest-existing study on the genetic causes of autism, comparing 996 autistic individuals to 1,287 people without the condition. Their results, which appear today in Nature, may provide unexplored avenues for treatment research, but also show in new detail the disorder’s sheer genetic complexity. For example, they have found “private mutations” not shared between people with autism and not inherited from their parents.

According to The Centers for Disease Control and Prevention, one in 110 children in the United States has autism spectrum disorder, and that the prevalence of autism among eight-year-olds has increased 57 percent from 2002 to 2006. There is no known cure, although intensive behavioral therapy helps some kids.

Hilary Coon, Ph.D., a lead author on the study and research professor of psychiatry at the University of Utah School of Medicine, said while research shows scientists are making progress in understanding the causes of autism, it is increasingly clear that autism is a multifaceted disorder with both genetic and environmental causes. “We are whittling away at it,” Coon said. “But a brain-related disorder, such as autism, is amazingly complex. It’s not really one entity.” [University of Utah press release]

For this study, researchers at the international Autism Genome Project wanted a closer, more detailed picture of the over 100 genes commonly linked to autism. They looked for rare variants–small deletions or additions to the DNA sequences that make up these genes. They found that people with autism had a higher number of these variants than those without the disorder, and that some of these DNA differences were not inherited. That means these DNA changes occurred either in the egg cell, sperm, or in the developing embryo.

“Most individuals that [sic] have autism will have their own rare form,” genetically speaking, concludes senior author Stephen Scherer, a geneticist at the Hospital for Sick Children in Toronto, Canada. That said, the team found that genes deleted in autistic patients tended to perform similar tasks. Many were involved in aspects of cell proliferation, such as organ formation. A number participated in development of the central nervous system and others in maintaining the cytoskeleton, which protects the cell and helps it move. “These are not random hits in the genome” and clearly have some connection to autism, says Jonathan Sebat, a geneticist at Cold Spring Harbor Laboratory in New York state. [Science Now]

Some believe that looking more closely at these variants may eventually lead to novel treatments.

Two categories of genes were affected more frequently than others: those coding for the neural cell development, and those involved in the signalling or “communication” between cells. Many of these same genes are thought to play a role in other neuro-development disorders. There may even be some overlap with conditions such as epilepsy and schizophrenia, the researchers said. “These and other recent findings have very real potential to lead to the development of novel interventions and treatments for these disorder,” said Louse Gallagher, a professor at Trinity College Dublin, one of the universities in the consortium. [AFP]

So what’s the next step towards such treatments? For now, it’s more big genetics studies. The Autism Genome Project has enrolled another 1,500 families and hopes for their next testing phase to look at people’s complete genomes and exomes (the part of the genome that codes for RNA or protein), reports Nature’s blog The Great Beyond.

The study has been hailed as a positive step by researchers, though one can imagine the parents of autistic children still feeling frustrated by the slow pace of progress. Perhaps to avoid giving false hopes, Dr Gina Gomez de la Cuesta of The National Autistic Society was cautious in her assessment of the study, saying:

“This study furthers our understanding of genetic variation in autism, however there is a great deal more research to be done. Research into autism is constantly evolving but the exact causes are as yet still unknown. The difficulty of establishing gene involvement is compounded by the interaction of genes with the environment. Genetic testing for autism is still a long way off, given that autism is so complex.” [BBC]

Related content:
DISCOVER: Galleries / Six Degrees of Autism
DISCOVER: Why Does the Vaccine/Autism Controversy Live On?
DISCOVER: Autism: It’s Not Just in the Head

Image: flickr / net efekt

CATEGORIZED UNDER: Health & Medicine, Mind & Brain
  • Richard

    I’m surprised that the article didn’t mention that autism occurs 4 times as often in boys than in girls. According to CDC, autism occurs 1/70 in boys and 1/315 in girls. To me, that would imply that the syndrome is quite different in boys and girls and any study should take account of gender.

  • Mkhan

    High incidence of autism is noted in children of Somalis who immigrated to Sweden or USA. In addition to genetic causes vitamin D deffeciency is also supected as incidence is very low in Somalia where sun is strong all around the year.

  • Alex

    FWIW: A psychologist specializing in autism, who dx’d me as an adult, told me that autistic girls were highly under-diagnosed.

  • Monkey


    Once, in university, I submitted a paper with two references in the text cited as “[professors name], lecture 2003”. I was handed back a paper with a good grade but the cautionary phrase “surely there is a better reference than this!”.

    So, as you link to the HuffPo…

    Surely there is a better reference than this?

  • Duff Smith

    I’m on the spectrum and I’m the quiet type who’s more proficient at writing than speaking. At the support groups I’ve attended there’s other autistic people that tend to talk my ears off. So, nobody needs to tell me that the disorder is genetically diverse.

    I feel like I’ve helped myself a lot by avoiding gluten and other forms of [what I refer to as] inflammatory glutamine. Yeast overgrowth with gut leakage, and protein in the blood — perhaps leading to cytosine methylation seems to me to be the most interesting suspect in the lineup at this time. And considering the epidemic of inflammatory disease here in America, I’d say autism is just the tip of an inflammatory iceberg. I think we’re waiting for the FDA to get off its butt. Their relationship with the food industry is just like that of big oil and its federal regulators. This is a “Gulf oil disaster” that grows below the visible surface of public perception, bigger every day.

  • autieauntie

    There is a beautiful boy on you tube under “kgaccount” who has autism and seizures and self abuses. Any research that could really help this type of autism?

  • Murray Cliff Pope

    Will there be any solutions to be connected to this website without having opt-in into the RSS? I am not sure exactly why however I can’t have the RSS loaded at my viewer though I can get it via my firefox.

  • Ross Coe

    No surprise that there is no mention that ethlmercury, aluminum and formaldehyde can cause genetic damage. All 3 are vaccine ingredients. I guess it would be too easy to admit that ,instead of hiding it till the uproar toned down, and Pharma has a chance to put spin on it and find a way to blame prents and inherited genes.

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