View Full Version : New Study of Genetics of ADHD


APSJ
06-24-09, 02:40 PM
ADHD Genes Found; Known to Play Roles in Neurodevelopment (http://sev.prnewswire.com/health-care-hospitals/20090623/DC3689223062009-1.html)

Pediatric researchers have identified hundreds of gene variations that occur more frequently in children with attention-deficit hyperactivity disorder (ADHD) than in children without ADHD. Many of those genes were already known to be important for learning, behavior, brain function and neurodevelopment, but had not been previously associated with ADHD."When we began this study in 2003, we expected to find a handful of genes that predispose a child to ADHD," said study co-leader Peter S. White, Ph.D., a molecular geneticist and director of the Center for Biomedical Informatics at Children's Hospital. "Instead, there may be hundreds of genes involved, only some of which are changed in each person. But if those genes act on similar pathways, you may end up with a similar result -- ADHD. This may also help to explain why children with ADHD often present clinically with slightly different symptoms."Among 222 inherited CNVs found in ADHD families but not in healthy subjects, a significant number were in genes previously identified in other neurodevelopmental disorders, including autism, schizophrenia and Tourette syndrome. The CNVs found in ADHD families also altered genes important in psychological and neurological functions such as learning, behavior, synaptic transmission and nervous system development.This study seems to lend support the idea that ADHD isn't caused by a single, or even a few, factors. As the article says, it seems quite consistent with the fact that people experience it so differently from one another. I would imagine that it could also start to explain why some people report such positive results from different supplements, while others find them useless, and differing responses to medications.

The fact that these genes are known to be involved with other disorders could also explain why its sometimes so hard to distinguish between ADHD and other conditions, and for people with co-morbidities to know what symptom goes with what diagnosis. If it turns out that the genetic causes of different disorders are better understood as clusters of genes with significant overlap between them, then assigning a symptom caused by a gene that fits into the clusters for two disorders, to one or the other, in a person who has both, would be arbitrary.

I would be interested to see more specifics. For example, I wonder if there were any genes that occurred in virtually all people with ADHD or genes that occurred in virtually none? I would read the study, but I've had poor success deciphering scientific journal articles on genetics.

Another deletion occurred in a gene for a glutamate receptor. Glutamate is a neurotransmitter, a protein that carries signals in the brain. While ADHD medications act on dopamine and serotonin, which are also neurotransmitters, this new finding may suggest an important role for glutamate as well, at least for some ADHD patients.This finding struck me as potentially having implications beyond whats stated in the article, but I'm not really sure why or what they would be. Can anyone help?

Dizfriz
06-25-09, 09:33 AM
APSJ
Good find.

While genetics is *very* much not my field, I keep up enough to understand that this research is important but not overly surprising in that we have known for a while that ADHD is a complex poly genetic disorder with a variable and also complex set of expressions and causations. It appears that we continue to get deeper into the details of the genetic base for ADHD.

As to the implications, we will have to wait until the scientific process digests it. It will have to be replicated, tested and most importantly evaluated on how the research suggested by this turns out.

The impact of the suggested research will be the most important factor in evaluating it's importance. In my view, this study will be a driver for a lot of research grants and may well turn out to be of major importance. Time will tell.


Overall, neat stuff. Thanks for posting it.

Dizfriz

kattsqueen
06-25-09, 10:12 PM
http://www.neurotransmitter.net/adhdglutamate.html

I found this and bookmarked it last week.I too have trouble following the research but here is some more for you,,
katts

PedroDaGr8
06-25-09, 11:30 PM
A little bit about what they are looking at:

SNPs - Single Nucleotide Pairs. For example:
A-T is an SNP. as is T-A, C-G and G-C. This basically means, one nucleotide and its matched partner on the opposite strand. So an example of an SNP mutation would be:

Normal
ATCGGCTA
TAGCCGAT

SNP change:
AACGGCTA
TTGCCGAT


WHat they were looking at the CNV deal with streches of repeated sequences.

For example:

---ACTGTGCTAACTGTGCTAACTGTGCTAACTGTGCTAACTGTGCTA---
---TGACACGATTGACACGATTGACACGATTGACACGATTGACACGAT---

I have bolded ever other repeating unit for clarities sake. THe --- indicate that the Genes continue on at either side.

A CNP change would be a change in the number of repeating units either more or less.

---ACTGTGCTAACTGTGCTAACTGTGCTAACTGTGCTA---
---TGACACGATTGACACGATTGACACGATTGACACGAT---

This would be a CNP change.

There are a WIDE number of ways this can affect the genes expression. For example, it maybe, four identical proteins are synthesised continuously and combined in a tetramer (four parts bound together as one) to make the ACTIVE protein. Delete one of these repeating units and you now only have three of the proteins made so your protein is no longer active as it is a trimer.