autism genetics/epigenetics

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Anybody out there interested in the genetics of autism/ epigentics of autism for example paternal/maternal imprinting. Having a hard time finding people to discuss this with, so I thought this forum was worth a shot

I heard about the epigenome briefly on the Science channel and knew it was going to cause a huge stir even then, once the word got out. If it does get out that is. As a mother w/ AS raising a daughter who's autistic, I can understand why it would cause a fuss. I doubt if the theory will be embraced. And good luck on getting a good discussion going. Post this in the Parents Forum and see what happens.

What was the program about? Was it on evolutionary genetics? Tell me more - it is interesting, but not actually what I was referring too
My interest isn't "controversial", it is in the actual genetic research, which is why I posted here - hoping genetics was someone elses "special interest".

It isn't my special interest-but often ponder the interactions of genes (inner environment) and circumstances (outer environment). My scientific comprehension is limited-however...

A couple months ago, I posted this (see below) on another ASD forum (some members are interested in neurology-have you tried asking about epigenetics there ?):
http://asdgestalt.com/viewtopic.php?f=23&t=1626

Nova episode on PBS-
Aired couple wks. ago: "Ghost in your Genes" about "epi-genetic" effects.
http://www.pbs.org/wgbh/nova/genes/
There's the issue of what environmental (health & stress) factors have on gene activation/triggering, which gets into nature/nurture (and trying to find meeting point for those dichotomies). Also seemed related to some things discussed in threads here-such as "sex differences in autism".
They briefly mention case of identical twin girls, only one of whom is autistic-and touch on notion that certain things happen depending on whether same gene comes from male (sperm) or female (egg), such as in their example of Angelman & Prader-Willi (I think). If gene comes from one parent, identical chromosonal abnormality appears as one disorder/disease, but if it comes from other parent, the child instead has the other condition.

I saw a documentary about epigenetics (the one belfast mentions). It's my understanding that they haven't yet been able to identify any epigenetic events associated with autism, even though they have done studies with autistically incongruent identical twins. You would also think that if autism is epigenetic, there would be more autistic incongruence in identical twins, since environment cannot be so tightly controlled. As it stands, I believe only 10% of autistic identical twins are incogruent.

I had to question the correlations the documentary drew between grandparents' epigenetic events and the lifespan of grandchildren. If a grandparent suffers famine, for instance, this could trigger all kinds of factors that could influence the longevity of one's descendants, like alcoholism, bad parenting, child abuse, or depression-- things that would be behavioral and not necessarily strictly biological.

but isn't it all about how many mercury-laden fish you ate while you were pregnant or something.

Just kidding.

I don't have anything against fish ... really.

thanks Will try gestalt.
Well I guess all of this may be a little controversial. I'm not big on the mercury conspiracy. either! It'¨s more the molecular side of things I'm trying to understand. The reason I am so interested in epigenetic mecanisms, is that regular genetics have a hard time explaining autism, and may of the loci actually identified are known to be related to epigenetic mechanisms, like 15q11-q13, which is also the Prader Willi/Angelmann syndrome area (imprinted area), X chromosome - more Turner girls with maternally derived X chromosomes, than paternal, are autistic. Chr. 7q, also linked to autism at 2 loci, likewize seem to been epigenetically modified.
Also Retts syndrome and Fragile X syndrome, which have phenotypical similarities with ASD, are known to be the result of epigenetic faults.
About the twins: yes there is a great concordance rate. and yes autism is 90% hereditary.
But there is random X inactivation in girls, so two identical girl twins have different gene expressions. This can make huge differences to phenotype, parallell to what is seen in Turner girls.

The October 2006 Neuropod podcast of the scientific journal Nature has a report that three different sets of genes contribute to the three groups of characteristics of autism. The item is about halfway into the podcast.

Work on the epigenetics of autism exists (link and here is another), but I don't know anything about it. You sound like you'll understand it better than I do.

thanks

Hi Katrine, sorry it took me so long to get back to you. (Fending off depression) I was talking about this.

http://www.sciencedaily.com/releases/20 ... 122855.htm

I started a thread in General Autism Discussion, it should be controversial to say the least. Intriguing research I think.

Does that mean that most cases of autistic incongruence are in identical twin girls?

i love this topic as well ^_^ am about to leave will come back later

It certainly is. Mind you, Sedaka knows her stuff much more than I do at this point. I'm only starting university this year. I hope to get involved with research in this area.

You will find unfortunately that this is unavoidably a controversial topic. There are many NT's (especially in the U.S. it would seem) who are determined to think that AS/Autism is a condition that needs curing and evidence that it is genetic doesn't do a lot to support their view. There are also quite a few people with AS who are equally against any possibility that genetics is the main "cause" of Autism.

No!
There is much more than the X chromosome going on. I am just implying that it is possible for twin girls to be incongruent because the random activation of one X instead of the other could theoretically push you over the so-called "autism threshold".

Genes are thought to raise autism susceptibility, rather than "cause autism"- 90% genetics leaves a huge 10% enviromental factors, where "enviromental" means anything not on the DNA sequence: psychological, chemical, biochemical, microbiological.... your guess is as good as mine.

What about heritability?

Concordance rates are 60% for autism and 91% for broader autistic phenotype in monozygotic twins, ~0 - 10 for dizygotic twins.