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New Genetic Studies Suggest Why Autism Is More Common In Boys Than Girls

New Genetic Studies Suggest Why Autism Is More Common In Boys Than Girls

Three new studies in Neuron reports that hundreds of spontaneous genetic mutations have been linked to autism. Such CBS News describes the findings as a “shocker,” previous research has indicated that de novo or spontaneous gene mutations can be linked to the neurodevelopmental disorder. As Time magazine says, the new studies differ from previous genetic studies, which looked at families with at least two autistic children; such families “may represent cases in which inherited genetic mutations may play a more prominent role in the disorder.” The researchers chose to focus on families in which only one child is autistic and other family members are unaffected.

The new research is ground-breaking because it is, according to the journal Nature, the “most comprehensive search yet for spontaneous genetic mutations” associated with autism spectrum disorders. Further, the new studies contribute to our understanding of why autism is currently diagnosed in four times as many boys as girls. As Nature notes, the researchers found that girls on the autism spectrum tend to have “many more mutated genes” than do boys, a finding that suggests “it generally takes a larger genomic change to cause autism in girls.” That is, for a girl to develop autism, a higher number of genetic changes have to occur.

Some background about work on autism and spontaneous genetic mutations, in which the genome is either duplicated or deleted:

In 2007, Michael Wigler, a geneticist at Cold Spring Harbor Laboratory in New York, and his colleagues showed that spontaneous mutations — those that arise for the first time in an individual, rather than being inherited — are important in about half of all cases of autism (see New mutations implicated in half of autism cases). A follow-up study in 2010, of 996 autistic individuals, found that people with autism carry a heavy load of rare duplications or deletions in regions of the genome that contain genes.

Now Wigler and his group, as well as a team headed up by Matthew State, a geneticist at the Yale University School of Medicine in New Haven, Connecticut, have expanded on that search, using higher-resolution techniques to trawl through the genome. The researchers searched the DNA of more than 1,000 individuals with autism and their unaffected family members, looking for rare mutations that duplicate or delete segments of the genetic code. The teams focused largely on spontaneous mutations.

Their results indicate that spontaneous duplications or deletions of at least 130 sites in the genome could contribute to the risk of autism. Wigler believes that in total there are closer to 400 such sites.

As Wigler says, such a large number of sites makes it difficult to develop therapies that might help more than a few patients. Still, like many parents and families taking care of an autistic individual, the promise of treatments (new types of medications, for instance) is heartening. 

My own teenage son Charlie has benefited from newer types of anti-seizure and other medications which have fewer harsh side-effects than their earlier predecessors. Such medications are far from a cure and must always be combined with education by trained and compassionate teachers and therapists. But they can make a huge difference in helping a child with multiple neurological challenges learn, communicate and — by helping to manage difficult behaviors — live at home and in the community.

 

 

 

Previous Care2 Coverage

Spontaneous Gene Mutations in Autistic Children: What Causes ASDs?

Understanding Autism: Causes, Genes, Brain Function, Symmetry

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Photo of students at Treehouse School in the UK by lynnefeatherstone.

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10 comments

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8:48PM PDT on Aug 2, 2011

Very interesting new material -- autism is heartbreaking for the individual and family -- so hard to live in a social environment if one is uncomfortable with others. I hope they can continue to make strides in finding out more and more effective treatments -- a cure?

6:49AM PDT on Jun 16, 2011

I do wish these articles would differentiate between those autistics who need intervention and those of us who function perfectly well and to a very high standard and need none. Every news article seems to paint the picture that we are all hopeless tragic "victims" who will need care for our entire lives, and this is not the case.

I would posit that those of us who are high functioning, with an extremely high IQ and "splinter savantisms" are another reason why so many of us fly under the radar, as it were. Because we need no intervention, we are not "seen" by the system. But we are here. And many of us are female.

Perhaps we are not as deeply affected as the males, or perhaps it's because we girls (even autistic) are better at multi-tasking, who can say? But please don't make the mistake of thinking every autistic is representative of every other. We have a saying in our community: "If you've seen one autistic, you've seen one autistic."

5:08PM PDT on Jun 15, 2011

Noted with interest.

6:48PM PDT on Jun 12, 2011

Interesting study.

1:32PM PDT on Jun 12, 2011

Please listen here: It's all because our DIETS are so farrrr from what we used to have...it's GARBAGE!!!
It's lack of proper animal proteins, and pollution, i.e., mercury in vaccinations (personal experience with one of my sons!).
Plus, all of these REFINED foods!
There is a movie clip on the Weston-Price Foundation about his research in isolated peoples, how their teeth are perfectly straight, no illnesses, nonviolent, and very happy and contented...does THAT ring a bell here with all of the propaganda, using us as 'guinea pigs'???

11:23AM PDT on Jun 11, 2011

I'm with Jenny Doughty.
These findings seem to point to mutations on genes that only have one copy in men, because the other copy would be on the "missing leg" of the Y chromosome.

9:35AM PDT on Jun 10, 2011

Read what the symptoms of autism are. It resembles a description of typical modern American behavior.

7:51AM PDT on Jun 10, 2011

One possible explanation strikes me. If autism is connected with deleterious gene mutations, then girls are less likely to be affected by them than boys if they are recessive mutations, because girls have X chromosomes. If the recessive genes are on one leg of the X, inherited from one parent, dominant genes on the other leg of the X inherited from the other parent ought to dominate. Boys have Y chromosomes, which means that recessive genes on one part of the chromosome are more likely to be expressed. But I'm not a geneticist and I could be totally wrong with that!

7:05AM PDT on Jun 10, 2011

Thanks Kristina,again it does make sense to have a blood test...BEFORE you get maried !!!!

1:27AM PDT on Jun 10, 2011

That's very interesting because I have noticed that it does seem more prevalent in boys than in girls. At the risk of sounding racist, I've also noticed that it seems to be more prevalent among Caucasian youth than in any other race. That may be somrthing else to take into consideration when studying genetic mutations in individuals. Thanks Kristina.

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Kristina Chew Kristina Chew teaches and writes about ancient Greek and Latin and is Online Advocacy and Marketing... more
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