View Full Version : autism genes possibly critical for brain evolution. perhapssimilar factors for AD/HD


datajunkie
03-24-14, 11:26 AM
http://www.sciencedaily.com/releases/2014/03/140321095510.htm
with the overlap of AD/HD and some autistics, could there be a similar evolutionary benefit to having some AD/HD genes?

Amtram
03-25-14, 06:32 AM
Bigger brain =/= better brain. This gene is implicated in the synaptic pruning that takes place in the third trimester of fetal development, which is necessary for normal development. The lack of synaptic pruning leads to overconnectivity, which is behind a good deal of autistic symptoms driven by hypersensitivity to stimulation.

fracturedstory
03-25-14, 07:27 AM
Yep, what Amtram said.

Although earlier today I read the the ADHD brain develops the same as NTs, but there's just a delay. Is there overconnectivity in ADHD too? Or is it just a lack of regulation?

Amtram
03-25-14, 11:13 AM
It seems from what the authors said that the gene is present in everyone, but its regulatory function is altered in autism. There have been mentions of it in relation to ADHD in some of the articles, but I don't know if there have been studies on it. Not enough ADHD brains donated to science, I suppose.

datajunkie
03-25-14, 11:15 AM
And the pruning goes on to at least 20's. With AD/HD, might also be overconnectivity or perhaps another path such as irregularities of receptors. My response to adrenaline gives me some low blood pressure crashes after a surge. I have symptoms of MVPS, mitral valve prolapse syndrome. This can have a combination of overly stretchy blood vessels and receptors for adrenaline/norepinephrine that over react to the drop. Like the separate settings on heat and air conditioning. One setting to raise the heat--signal for adrenaline, and another that it is time to cool down--lower A. If these receptors are over reactive and lower the A/NE too much, the already stretchy blood vessels dilate too far, blood pools in the abdomen, not enough blood for the brain and body. Can lead to a whipsaw up/down cycle as the brain hits the panic button for more blood, burst of adrenaline. not fun.
But if some errors if sensitivity and response combine with over/under connection in parts of the brain and body, might affect AD/HD. I've heard of one dopamine receptor gene that is less sensitive and harder to get D into the receptor. But adrenaline helps this receptor use the A. Sort of like a hammer to smack it into place. Leads to thrill seeking behavior and I think linked with some aspects of AD/HD. Might be ok as long as adrenal glands hold out.
It would not surprise me to find that some aspects of AD/HD are pro evolutionary if dealt the right set of cards from the genetic deck. The article indicated quite a few CNV's with this trait, Copy Number Variations where extra genes are stacked up, sometimes 6 deep instead of the normal 2 and in some CNV's genes are missing. AD/HD could well be like this. Extra copies of a gene that is useful if heterozygous and balanced by a different gene but if homozygous or several copies without balancing traits, becomes AD/HD. The hand dealt has jokes that give 5 of a kind and some cards are missing.

datajunkie
03-25-14, 11:20 AM
It seems from what the authors said that the gene is present in everyone, but its regulatory function is altered in autism. There have been mentions of it in relation to ADHD in some of the articles, but I don't know if there have been studies on it. Not enough ADHD brains donated to science, I suppose.

Amtram, the research I'd like to hear more of is identical twin studies over time. Since not all twins are affected, what is different with the non affected twins? May not need to examine their brains after death as much as track their epigenetics and perhaps levels of toxins, diet, illness, etc. to see what environment and random gene inactivation does. Check hormone, neurotransmitter levels, things that can be checked via lab work over time against symptoms, behavior and cognitive testing.

Amtram
03-25-14, 11:27 AM
I was mistaken - been doing too much reading in a single sitting, stuff is getting mixed up in my head. From the authors:
In 2012, Sikela was the lead scientist of a multi-university team whose research established the link between DUF1220 and the rapid evolutionary expansion of the human brain. The work also implicated DUF1220 copy number in brain size both in normal populations as well as in microcephaly and macrocephaly (diseases involving brain size abnormalities).

The first author of the autism study, Jack Davis, PhD, who contributed to the project while a postdoctoral fellow in the Sikela lab, has a son with autism and thus had a very personal motivation to seek out the genetic factors that cause autism.

The research by Davis, Sikela and colleagues at the Anschutz campus in Aurora, Colo., focused on the presence of DUF1220 in 170 people with autism.

Strikingly, Davis says, DUF1220 is as common in people who do not have ASD as in people who do. So the link with severity is only in people who have the disorder.

"Something else is at work here, a contributing factor that is needed for ASD to manifest itself," Davis says. "We were only able to look at one of the six different subtypes of DUF1220 in this study, so we are eager to look at whether the other subtypes are playing a role in ASD."

Because of the high number of copies of DUF1220 in the human genome, the domain has been difficult to measure. As Sikela says, "To our knowledge DUF1220 copy number has not been directly examined in previous studies of the genetics of autism and other complex human diseases .So the linking of DUF1220 with ASD is also confirmation that there are key parts of the human genome that are still unexamined but are important to human disease."

Amtram
03-25-14, 11:30 AM
One article about twin studies: http://www.karger.com/ProdukteDB/Katalogteile/isbn3_8055/_92/_37/KIMH176_02.pdf

A full-text meta-analysis with links: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3263324/

datajunkie
03-25-14, 11:58 AM
will check them out, thanks for the links

mildadhd
03-25-14, 09:50 PM
http://www.sciencedaily.com/releases/2014/03/140321095510.htm
with the overlap of AD/HD and some autistics, could there be a similar evolutionary benefit to having some AD/HD genes?


Yes, I think so.

Different variations of expression, in response to a variety environments, seems important for survival.


Do most people with Autism have ADHD?

Do all people with Autism have over abundant expression of the epigenetics being discussed?

I mean can "under abundant" development also occur?


I need to learn more about these topics, I hope this makes sense, thanks for the discussion.



Peripherals