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.
Conclusion
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.