Monday, 13 January 2014

Epigenetics and Autism

I have touched on the subject of epigenetics in a previous post; it is a new area of science that shows how the environment can modify your genes.  Rather than you being purely a product of your parents’ genes, you actually also have both your own environmentally acquired epigenetic changes, and some of the acquired epigenetic changes of your ancestors.

These acquired epigenetic changes are caused by things like emotional trauma, chemical insults and even smoking.
Epigenetic control systems generally involve three types of proteins: “writers”, “readers”, and “erasers.” Writers attach chemical marks, such as methyl groups (to DNA) or acetyl groups (to the histone proteins that DNA wraps around). So-called “readers” bind to these marks, thereby influencing gene expression; erasers remove the marks.


In theory epigenetic changes should be reversible, but this is not simple.
You may recall in an earlier post about asthma, we learnt that it is very hard to treat former smokers.  Once a person has smoked heavily, a change occurs whereby the body remains in permanent oxidative stress and conventional asthma drugs are not very effective.  The fact that the person gave up smoking 20 years previously does not help.  The only way to treat the patient is to first treat them with an antioxidant and NAC was the most effective; even then the result is not so good.

Epigenetics and Autism
It is said that autism is caused by a combination of genetic and environmental factors; but it might be better stated that autism is caused by genetic and epigenetic factors.  Those epigenetic factors would include all the accumulated environmental factors affecting that person and his ancestors.

As modern life becomes more distant from the village life of our ancestors, you can imagine a gradual build-up of environmental and stress factors.  If you cannot erase some of those marks, you will reach a point where the “tainted” DNA will produce aberrations.  Such aberrations might trigger cancer in one person and autism in another. 

Epigenetic Drugs
Cancer was identified very early as being a likely consequence of epigenetic changes.  Cancer research is very well funded and some epigenetic drugs are already available.  The idea is that epigenetic drugs should selectively target reversible epigenetic changes

A particular problem is that the drug has to act very selectively.
If you were able to erase all those chemical marks on someone’s DNA, there would most likely be some unwanted and unanticipated changes.

One pioneer in this field is a US firm called Acetyton Pharmaceuticals.

Epigenetic Research in Autism
The good news is that research has recently started in this area, and it might eventually lead to the possibility of reversing some of those unwanted epigenetic changes.

Here is rather heavy study from Kings College in London:-

Autism spectrum disorder (ASD) defines a group of common, complex neurodevelopmental disorders. Although the aetiology of ASD has a strong genetic component, there is considerable monozygotic (MZ) twin discordance indicating a role for non-genetic factors. Because MZ twins share an identical DNA sequence, disease-discordant MZ twin pairs provide an ideal model for examining the contribution of environmentally driven epigenetic factors in disease. We performed a genome-wide analysis of DNA methylation in a sample of 50 MZ twin pairs (100 individuals) sampled from a representative population cohort that included twins discordant and concordant for ASD, ASD-associated traits and no autistic phenotype. Within-twin and between-group analyses identified numerous differentially methylated regions associated with ASD. In addition, we report significant correlations between DNA methylation and quantitatively measured autistic trait scores across our sample cohort. This study represents the first systematic epigenomic analyses of MZ twins discordant for ASD and implicates a role for altered DNA methylation in autism.


For those of you who prefer some milk in your coffee, those helpful people at the MIND Institute in Sacramento have produced a series of video lectures on this very subject.
Here is the full list:

 and here is one particular video.

Epigenetics would help explain the increasing prevalence of ASD in the most developed countries.  It also opens the door to potentially highly effective treatment mechanisms to many currently incurable conditions.

Perhaps, by chance, one of the new epigenetic drugs developed for cancer will have a positive effect in ASD.



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