Researchers link early stem cell mutation to autism

Jun 30, 2008

In a breakthrough scientific study published today in the Proceedings of the National Academy of Sciences, scientists at the Burnham Institute for Medical Research have shown that neural stem cell development may be linked to Autism. The study demonstrated that mice lacking the myocyte enhancer factor 2C (MEF2C) protein in neural stem cells had smaller brains, fewer nerve cells and showed behaviors similar to those seen in humans with a form of autism known as Rett Syndrome.

This work represents the first direct link between a developmental disorder of neural stem cells and the subsequent onset of autism.

The research team was led by Stuart A. Lipton, M.D., Ph.D., a clinical neurologist and Professor and Director of the Del E. Webb Neuroscience, Aging and Stem Cell Research Center at Burnham.

"These results give us a good hint of how to look at Rett Syndrome and potentially other forms of autism in humans," said Dr. Lipton. "Having identified a mutation that causes this defect, we can track what happens. Perhaps we can correct it in a mouse, and if so, eventually correct it in humans."

Discovered in Dr. Lipton's laboratory, MEF2C turns on specific genes which drive stem cells to become nerve cells. When MEF2C was deleted from neural stem cells in mice, there was a faulty distribution of neurons accompanied by severe developmental problems. Adult mice lacking MEF2C in their brains displayed abnormal anxiety-like behaviors, decreased cognitive function and marked paw clasping, a behavior which may be analogous to hand wringing, a notable feature in humans with Rett syndrome.

"There's a yin and yang to this MEF2C protein," said Dr. Lipton. "My laboratory recently showed that MEF2C induces embryonic stem cells to become neurons. In this new research, we show that knocking out MEFC2 in the brain results in mice with smaller brains, fewer neurons and reduced neuronal activity. The commonality is the protein's association in making new neurons."

Rett syndrome, a form of autism, afflicts more girls than boys and results in poor brain development, repetitive hand motions, altered anxiety behaviors and the inability to speak. Patients with Rett Syndrome also suffer from seizures and other debilitating neurological symptoms.

Source: Burnham Institute

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Bbrhuft
5 / 5 (3) Jul 01, 2008
Rett syndrome is not a form of autism, it is a genetic condition that mainly affects girls, who display symptoms reminiscent of autism. Autism is a condition defined by a set of behaviors - autistic behaviors are also seen in Brittle X, Downs Syndrome & Tuberous Sclerosis. Thus, according to the logic that includes Retts under the PDD umbrella, several other conditions also deserve inclusion as PDDs, which is clearly ridiculous.

I haven spoken to geneticists; I feel that the causal exploration of autism is stymied by the lack of cross disciplinary understanding of the psychology of autism amongst biologists and geneticists. The geneticists I met failed to appreciate that autism is, expressively, highly heterogeneous, and that it is a spectrum ... it is Autisms (plural). Any progress will be painstaking and only incremental.
googleplex
not rated yet Jul 01, 2008
IMHO such medical dogma is primitive and frustrating. The current model of medically treating people the same will be thrown out of the window. In the future treatments/drugs will be customized for different DNA types of people. Customized drugs for specific DNA types.
The naming of genetic variations will need to be revised to reflect the true underlying complexity. Reductionism is a usefull tool, however the true universe is complex.
There is always the chance of a breakthrough. DNA sequencing is improving exponentially according to Moores law. At some point decoding of DNA for each individual will be as available as blood typing is today.
It must be said that DNA is less than half the picture. DNA is the source code. The computer is the cell. Without a complete molecular model of the cell DNA is fairly useless. Hopefully someone will set up a central database/wiki of cell function. Currently there is no co-ordinated effort to document the molecular model the cell.
There is however another issue. The way the cell expresses/reads the DNA can change over time. The DNA cell is not a static machine. It is dynamic and adaptable to its environment.