Should DS3 be tested for Mosaicism?

[PeachyFleshCrawlingWithBugs]

As many of you will know, DS3 has noted delays, most clearly in spech / langauge but generally he's about 2 yeras delayed. ASd ahs been the dx put about most by the Paed but Dh and I have been wondering about this for a bit- in terms of his development lately the social side has moved forwards far faster than any other, and he just isn't like ds1, iykwim?

We dor ealise we may be in denial.

However, the most similar to any child we know is a child with Downs Syndrome that ds1 attends an SN group. That probably wouldn't be enough to make us wonder, except that when I was pg with ds3 all the blood tests for Downs DID come out as high risk- we chose not to have an amnio.

Paed says its not GDD as he walked within the norm frame (yes, but only just- the other 2 walked at 10 months and 11, whilst ds3 walked at 16 so not 'norm' for our family)

SALT still making noises about Speecha nd alnguage disorder when we last saw her (a good whilse back as we have been put to the community team and the inevitable waiting list).

There are lots of possibles but nothing quite fits- today though someone at SN Rugby queried Mosaicism as a possibility 9they commented on how their son (the one with DS) and ds3 had amtching eyes and seemed so similar in some ways).

Now granted Dh and I are starting to get desperate for a DX that we feel 'fits' DS3 as we would like some clues about the future with him. None of the explanations so far quite got ds3 right, and nobody ahs yet offered any ways to help him at all, bar BIBIC I suppose.

Anyone any ideas?

Bear in mind that even if you do get a diagnosis,it might not serve any purpose.

I think about 70% of general learning disabilities are of unknown aetiology.

Have never heard of this condition Peachy. Is it similar to Downs in some way?

I know MD, but if someone said 'its a nameless disorder' we'd probably feel happier than now- I know that probably doesn't make sense, but the ASD just feels so wrong at the moment. The one thing DS3 is developing into is a people person suddenly- quite the opposite of DS1. DH in aprticualr is scared that suddenly ds3 will lose his happy go lucky eprsonality and morph into DS1, who really is sadly not a happy bod- I'd go so far as to say it haunts dh that might happen.

cornsilk, sort of- there's different types, but 9and I am no geneticist- A level bio my max level LOL) its a sort of gradient; trisomy whereas Downs mosaicism 9and there are others) are parial- indeed the books say most peole have some level, but in some individuals the balance is keyed the toehr way, iyswim?

Ah, forgot he already had a diagnosis.

Your feelings are shared by a great many of the families i work with. Entirely natural to want to be able to some something up (althoguh remember that a 'syndrome' is often just a convenient way of bundling up a bunch of symptoms.

I rememember one mother saying to me

'I want to know what it is called so that when people ask me what is wrong with him I can give them a name and leave it it that.'

For symptoms, should have said characteristics.

It sounds like a distinct possibility, doesn't it, and would be easy to test for. I would go for it- it would be absolutely worth knowing if it was that because there might be things they would want to keep an eye on, and might well make it easier to access support.

Peachy - if its the text to confirm downs, then go ahead, its very simple and should be conclusive. My dd3 was found to have a translocation type of DS which is rarer than standard trisomy 21, but not as rare as mosaicism. It makes no difference to her development, but as you say, it helps to know. All the best.

test not text !!

Apparently its a skin biopsy?

ahven't mentioned to aped yet (bit worried we'll upset her questioning her, as we're also reliant on her for DS!) but its got to be worth a shot- this child is slowly turning into the most sociable kids I've ever met!Yet the spech and language suggestion (no firm dx as yet just suggestions) wouldn't explain a lot of his delays, why he's still in nappies etc.

Thanks for all the advice- to be honest i felt a bit nutty asking but this ahs been niggling DH and I for ages, we just hadn't mentioned it to weach other iyswim.

Peachy - I don't know your background so forgive me - but has your ds3 been seen by a clinical geneticist? They are generally very highly skilled in picking out genetic syndromes (like the eye shape). Also, apologies if you know all the stuff in this post already but....

Bear in mind that mosaicism is a broad term and simply means a mixture of cells, some cells normal and some with a difference (so in mosaic Down Syndrome there would be some normal cells and some with an extra chromosome 21). The 2 types of cells will be in different proportions in the body, so eg. the blood may be completely normal cells, but the skin may have both cell types, sometimes the 2 cell types are only found in internal organs so testing would be very intrusive and painful.

Mosaicism for trisomy 21 (Down Syndrome) should first be tested for by blood chromosome analysis (the test looks at a lot more cells than the standard chromosome analysis, so even if your ds has had a karyotype test done, it should be reassessed), and if that is still normal, then you could have a skin biopsy, but I have heard that this is very painful - they need to get a piece of skin that is deep enough for there to be living cells present so that they can grow these cells and look at the chromosomes.

I would have thought the best option would be to have a good geneticist to review your ds's history and make their judgement...but you may have already done that.

No, we haven't yet seen one- we were going to ask if its possible to go rivate actually- we were on a waiting list for a Paed for a year, he saw her last december but becuase DS1 has HFA she very quickly assumed a link- which so did we at the time, it just doesn't tie in now, several months later. Actually she mentioned that herself a few weeks ago when we saw her- said she was planning to wait a few yeras before a dx of ASD would be give.

Should we ask for a referal to a geneticist, or is their a private system?

Sorry, I don't know if there is a private system - although since it exists in other fields of medicine I would guess there was.

Peachy, you could ask gp for referral to geneticist - we were referred cos of DD3's Downs being the translocation type, and this is sometimes an hereditary condition. Not in our case as it turned out.
Millarkie, very interesting about mosaicism showing differently in diff parts of the body..... we only needed a blood test which was back within a week. Obviously a skin biopsy sounds more invasive.

The thing is that mosaicism can occur in "patches", so it could be that most cell in the blood had two copies of chromosome 21 but most skin cells had three. Unless your dd has mosaicism, headgirl, there would have been no need to test anything other than blood because it would reflect what was going on throughout the body.

I agree with Millarkie, haven't heard of private geneticists but you could ask. There is loads of expertise in Cardiff, as I'm sure you know

We tried to get a private geneticist in London, it was virtually impossible! We went NHS in the end.

My DS has many usual characterisitcs of DS but has not been tested for mosacism, despite a mention to Paed - Geneticist has done basic Karyotype, she said his face not DS.

When I started Portage group a mum with a ds dd thought my DS did have DS iykwim!

His relevant traits (I feel are) bilateral single palmar creases, epicantic folds, hypertolorism, down slanted eyes, 'squashed' bridge of nose, (small) sandal gap and tiny feet (age 3 size 6), tongue thrusting, heart valve problems, low muscle tone, short stature (as well as GDD)...I could go on...

Good luck in your quest, I've sort of given up with mine, too many other battles to fight etc.

I think we'll discuss this with the Paed- she is very understanding, i think she understands our need to at elast try for an answer!

Thanks everyone.