Chromosone testing:Autism

[cyberseraphim]

The Background

DS is autistic. We have already been to the hospital twice to give blood for testing purposes. Fragile X has already been ruled out. We have now been asked to go back to give blood a third time because there is a 'small structural abnormality' in the chromosone that can't be excluded without a further test. He isn't too bad by ASD standards about having blood taken but has anyone else had this kind of testing done? I'm sure it's just another blind alley and we will not find out anything about the cause of his ASD but I just wondered if anyone else has had a chromosone defect linked to ASD in their child.

interested bump

I have read a tiny wee bit about the chromosone thing when I was reading about SPD.

my son is pre DX (poss Autism/ASD) and has also had bloods taken twice already (and they botched both and had to have them retaken ) and the chromosome tests came back "inconclusive" WT* does that mean???

So i too would be interested if anyone has any clue at all. Thanks

Wow - this all sounds a bit x-files - it would be interesting to know what a 'conclusive' test was?!?

Which chromosome? Was it picked up during the Frag X test or from a standard karyotype?

Sorry - just realised I probably sounded a bit crass - just meant it didn't really sound like they knew what they were looking for.

i wasnt privy to that sort of information, after all im only the childs mother

and of course im not a doctor and couldnt possibly understand any of what was going on, according to the paed as he was rolling his eyes at me and fobbing me off with "well, it could be anything really, not being enough sample, it being taken too late (it has a 'best before' date???), or ... something else" then he changed subject by talking to the trainee doctor instead.

It's bad enough when you have to take children to be poked and prodded and perform on demand let alone when consultants don't even have the decency to explain what it's all about!

oh that's crap. I don't think they have any idea how stressful genetic testing is.

projects.tcag.ca/autism/

Warning: scientific site.

In plain English: Human body is built out of instructions on squiggly bits in our body's cells called chromosomes. If bits are missing, or in the wrong place, the theory is that this may cause autism.

Looking at that site I've put the link to above, strangely, the scientists seem to be finding faulty bits in any or all of the chromosomes, in all sorts of places on them, and then saying "Aha!".

I suspect it's a load of rhubarb. Best theory on autism I've seen so far is that the brain has its own tiny "electrical wiring crew", (not quite the right words, but it'll do) whose job it is to nip round connecting up all the brain wiring in the right orders. (Info from New Scientist magazine a few months ago). And sometimes they re-wire it wrongly or differently. No-one has a clue why. Until fairly recently they hadn't even realised they were there, let alone what they did (or how).

Well there are many different causes of autism. When chromosomes undergo a structural rearrangement (such as two bits swapping or two joining together) it can happen with absolutely no problems at all. Other times tiny bits of DNA can be lost. It may be something like that they're looking at, or something totally different. But they should have told you.

There are loads of genes now mapping to be potential autism candidate genes. But many have an environmental agent that acts on them as well.

They should give you more info though. Can you get genetic counselling?

I think that is the problem finding a genetic cause for autism in that there are so many genetic factors both inherited/familial and de novo mutations that operate to create what they call a 'common pathway' to autism

DS1 had a blood sample taken last year, the results ruled out fragile x. We were then asked to give a second sample so other chromosomal abnormalities could be ruled out. Now we have been asked to give a 3rd sample because the 'quality was not adequate to exclude a small structural abnormality'. In a way it would be nice to have an 'answer' but I suspect it's not likely to happen.

No we don't know which chromosome is being tested

Oh OK I think I know what they've done.

They did a Frag X test - this was probably what's known as a genetic test- so they looked simply for the Frag X gene. Usually this result would (I think) be confirmed by a karyotype - so they would actually physically look at all the chromosomes- rather than just looking at a band on a gel that would indicate a specific gene. This allows you to pick up rearrangements etc. BUt it sounds as if the second sample just didn't generate good enough slides/chromosome spreads. That's not really unusual. So they just couldn't see what they wanted to see (think about a smear test- sometimes you just can't see the cells you need to and so it has to be redone).

I've never worked in a human genetics lab, (only mouse)- so I'm not entirely sure what the standard procedure involved in Frag X testing is. But it sounds as if they're just trying to check the karyotype.

The conference I recently attended was really talking about their being no one common pathway to autism. Something that I thought was interesting though was that families where you saw the broader autism phenotype in relatives (so aspieish dad and uncles etc) seemed to be associated with many genes contributing and was associated with siblings also having autism. Families where there was no broader autism phenotype in the family, and unaffected male siblings - seemed to be associated more with single genes.

That (broader phenotype would fit us then - we have ASD traits in many family members including brother with high functioning autism. The professor who dxd DS1 thought I might have Aspergers too but I didn't want to take that theory any further - unless I could get DLA for myself of course ! I think you are right about test, it is just making sure the last box is ticked and they need to re run test to do that.

that was a lot of information to take in 60 seconds....

hang on will read carefully...

We have been offered genetic councelling - apparently: "a 'super fabbo geneticist' is visiting in a couple of months and I would like her to take a look at these notes, and see what she can advise, see if theres anything that she can think of to look for... Although if I cant find anything, I doubt she will, and if she does its time for me to retire!" at that point he sat back with his hands behind his head smugly.

Incidentally, DS1 has ADHD, dyspraxia+, MIL has ADHD. My father has ADHD, My Grandmother had AS... so i think its hardly surprising that it looks genetic with DS5

Incidently, it was very interesting info you gave there Amber. Jimjams - thanks, i shall go next time armed with the right questions. Cyber, YIKES - I think I wouldnt want to take too close a look in the mirror either, just in case!

ps did not mean anti aspergers in not wanting dx just too much else going on at the moment