Researchers have taken significant steps towards determining the mysterious causes of autism, with the discovery that two-thirds of autistic people have a genetic variant that influences how neurons connect with each other. An additional study found 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 way brain cells connect [Los Angeles Times].
The two studies were made possible by improved technology that allowed researchers to compare the genomes of thousands of autistic people to those of thousands of people without the disorder, looking for genetic differences between the two groups. Previous studies that have identified several genes that are implicated in autism, but … they are extremely rare and account for a very small proportion of autism [New Scientist]. The two studies, both published online by Nature, won’t lead immediately to new treatments, but they open up important new avenues of research.
The first study identified genetic variants on a region of chromosome 5 that is squarely between two genes that produce cell-adhesion molecules, which govern how neurons connect to each other. The variants don’t raise risk all that much–about 20% for the strongest. But, [lead researcher Hakon] Hakonarson says, the work is exciting for two reasons: 65% of [autistic] kids in the study had that variant, compared with just under 60% in the control group–a difference that, across a population, is significant, he says. And even more important, the link with cell-adhesion molecules firms up suspicions that in autism, “nerves don’t connect normally or break down” [ScienceNOW Daily News].
The second study scanned the genomes of people with autism for copy-number variants (CNVs), in which segments of DNA are either replicated or deleted. The researchers turned up nine repeated or deleted regions, some of which had been pinpointed previously. Four of the CNVs were in genes that belong to the ubiquitin gene family, which helps control nerve connections [ScienceNOW Daily News].
Researchers and families of autistic children are applauding the findings as a real step forward, but autism expert Simon Baron-Cohen notes that genetic variants tell part of the story, but not all. “The challenge for future research will be to establish which aspects of autism they can explain, how many of these genes are necessary and sufficient to cause autism, and how they may interact with environmental factors,” he says [New Scientist].
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Image: Children’s Hospital of Philadelphia
April 29th, 2009 at 5:33 pm
Maybe the gene is somehow triggered around 12-15 months and skips 20 generations (at least it did in my family). Otherwise you’d think autism was caused by vaccines.
April 29th, 2009 at 6:14 pm
Why bother with this research when everyone knows that vaccines cause autism?
April 29th, 2009 at 7:54 pm
Autism is evolution in action – just the kind of evolution that would not get passed down in the wild. Many autistic people are able to lead fairly normal lives, many are not. Some appear to be super-geniuses but only in very narrowly specific ways (but then again almost any genius is smart in a narrow way – a brain surgeon can’t fly a rocket or build a house) – but in a less civilized milieu few if any would survive to pass on their genes. More and more will, it makes me wonder what the next 100 years of humans is going to look like, because science will be battling evolution on this front.
April 29th, 2009 at 10:23 pm
I think people who have no background in biology or neuroscience shouldn’t speculate on what may or may not cause something. And bensmyson, 20 generations? That would be about… 500 years?
And big john, you’re joking right? We’re not talking about research into discerning the shape of the earth to settle a flat vs. round debate. The cause(s) of autism is a very contentious discussion. I hope you were joking but the fact of the matter is, even if you weren’t, somebody probably would have said the same thing.
April 29th, 2009 at 10:26 pm
And Nick, are you promoting Eugenics?
April 30th, 2009 at 5:43 pm
@bensmyson:
“Maybe the gene is somehow triggered around 12-15 months”
Perfectly plausible to anyone with even the most rudimentary understanding of gene expression.