Friday, November 12, 2010

Modeling Rett Syndrome

Picture from Wikimedia Commons
According to a new paper, published in the Nov 12 issue of Cell, it may be possible to grow a model of what neurons look like in people with Rett Syndrome.  I have to say, if this is a real result - and can be reproduced by other groups - then this is potentially a huge leap forward for people with Rett Syndrome.

For those of you who don't know, Rett Syndrome is a form of autism that is somewhat different from other types of autism.  Rett Syndrome is very rare and is seen primarily in girls instead of boys.  It tends to involve more motor issues and be more severe than "typical" autism.  Also, children who are affected might not respond as well to standard autism treatments such as ABA.

However, unlike other types of autism, a possible mechanism for the problems of Rett Syndrome has been identified - a mutation in the methl-CpG-binding protein 2 (MeCP2) gene.  And, more importantly, recent research has shown that it might be possible to reverse the effects of this mutation and effectively "cure" people of Rett's.

With that in mind, forget about all of the media reports that are talking about replicating autism in a dish and instead focus on what the researchers actually accomplished.

At the risk of over simplifying, the researchers took some cells from girls with and without Rett Syndrome, turned them into a type of stem cell, and then had them grow into neurons.  The neurons from the girls with Rett's had significant differences from the neurons grown from the "typical" girls.  The differences seen in these cells were similar to what has been seen in mouse models of Rett's and in human autopsies of people who had Rett's.

So basically, researchers grew neurons that closely mimic what real neurons would be like in people with Rett's.  Given that it might be possible to reverse the damage cause by Rett's, this ability to grow neurons and test how they react to different treatments is invaluable.  The researchers already presented some data in the paper showing that certain treatments that were thought to be helpful with Rett's actually do help.

I can't really do the subject justice, so if you are interested in the topic I suggest that you read the paper.  The paper, along with a good introduction, is freely available from the journal's web site.

The downside here, if there really is one, is that results don't apply to other forms of autism.   In Rett's, we have a known mutation, some idea of what the model should look like, and a way to judge the results.  In other forms of autism, we have no real clue what causes the problems and no idea of whether a specific type of cell would be a good model of anything.  Having some sort of biological mechanism to target can make all the difference in the world.


Marchetto, Maria C N et al. 2010. “A Model for Neural Development and Treatment of Rett Syndrome Using Human Induced Pluripotent Stem Cells.” Cell 143:527-539.

Walsh, Ryan M, and Konrad Hochedlinger. 2010. “Previews Modeling Rett Syndrome with Stem Cells.” Cell 143:499-500.

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