chromosomal disorders other than T21, 13, & 18?

[Anonymous]

I'm 41 - 14 weeks pregnant and just had a negative MaterniT21 results and a low risk readong on my NT screen. My history has me vigilant: at 35, I was pregnant and Trisomy 13 was detected by the 20 week ultrasound and confirmed with amnio [this was after an OK result on NT Screen]. We terminated the pregnaicy as soon as possible.

I am now agonizing over the same issue- should I go forward with Amnio? I'm leaning toward it. I want to know as much as possible and the MaterniT21 doesn't test of other chromosomal abnormailities or open neural tube defects. I'm also somewhat concerned about how new this test is. The literature says it screens for T21 and "also is effective in detection of T18 and 13" - but doesn't go as far as to tout the 99% accuracy for those. On top of this, I'm not sure I should be so scared of doing an amnio -- a recent study found that amnio risk typically cited is overstated and is closer to 1 in 1600.

Still wavering back and forth - I have to just make a decision and accept it no matter what happens.

[Anonymous]

Oh and should add - my perinatologist sees a big difference between the amnio and CVS. He is experienced and one of the best - but thinks the 4 week wait is worth the much reduced amnio risk unless there's a strong indication in earlier screens of an issue.

[Anonymous]

Anonymous wrote:Oh and should add - my perinatologist sees a big difference between the amnio and CVS. He is experienced and one of the best - but thinks the 4 week wait is worth the much reduced amnio risk unless there's a strong indication in earlier screens of an issue.

That is interesting - frankly, it's the first time I hear or read that. Generally, the medical opinion seems to go into the direction that the risk of CVS is very similar to amnio, and that the previously reported higher miscarriage rates are just due to the fact that CVS is done in the first trimester, where many miscarriages happen anyway. That is what the two perinatologists that I have talked to told me.

The problem with these statistics overall is that they count every loss that occurs within four weeks of the procedure as being caused by it - when in most cases, they do not know whether the loss would have occurred anyways.

If I were in your position, I would not hesitate getting an amnio, but everyone has to make that call for themselves.

[Anonymous]

I just wanted to comment on the post that states the Amnio can detect deletions. That is too simplistic---it can detect a deletion if the deletion is big enough. There are many chromosome disorders (of deletion type or uniparental disomy) that will not be caught. There never is a guarantee, even with an amnio. My son has a chromosome disorder that generally is not caught by amnio...a few cases are but the majority are not.

[Anonymous]

Anonymous wrote:Talk to your doctor. Do the maternity 21. If your numbers are at risk they will recommend the amnio. The maternity 21 is supposed to take the place of the amnio. I understand your concerns but, don't want you to have tests you don't need. My genetic counselor was great with answering all of our questions and concerns.

My OB says they view the Maternit21 as a screening test, along the lines of the NT scan. If they see anything that concerns them on either of those tests, they'll recommend moving forward with a CVS or Amnio, but they definitely don't view Maternit21 as diagnostic.

[Anonymous]

I see high risk doctors who made it clear that fromt their perspective the Materniti21 was not supposed to replace the Amnio.

[Anonymous]

Anonymous wrote:I just wanted to comment on the post that states the Amnio can detect deletions. That is too simplistic---it can detect a deletion if the deletion is big enough. There are many chromosome disorders (of deletion type or uniparental disomy) that will not be caught. There never is a guarantee, even with an amnio. My son has a chromosome disorder that generally is not caught by amnio...a few cases are but the majority are not.

Amnio (and CVS) can detect deletions/duplications if you get the fluid sent to lab that does a microarray. We did the "Precision Panel" through Signature Genetics in a addition to the normal karyotype. Insurance paid for it.

[Anonymous]

I was told the other trisomies are rarer and less likely to go to term.... but this is between you and the genetic counselor..

[Anonymous]

OP here. Thank you so much for all the thoughtful responses. While I know that ultimately this is a decision that has to be made by both me and DH -- and no one else -- it really does help to hear the thought process that many of you went through, and are going through currently in some cases.

Hearing about the two PPs that chose to do a microarray was particularly helpful, and especially good to hear that insurance covered it (at least in one case). But I also really appreciate the advice from 20:20 that testing can be ambiguous -- and I am truly sorry for the gut-wrenching decision you (and others) have had to make.

I'm still not not sure whether we will pursue the amnio once we get the Maternit21 results back this week, but I am a lot closer to making a decision. For those of you that suggested a CVS, at this point it is not possible as I am 13 weeks. Although, honestly it was not something I was interested in -- largely because a friend recently had a miscarriage after having one, which hit a little to close to home.

I have talked to my genetic counselor about a lot of this, but if I gather any additional information in my subsequent talks, I will pass it along. Thank you again, I so appreciate you all taking the time to respond.

[Anonymous]

It tests for the sex chromosomes now.

[Anonymous]

PP here. Sorry. I didn't realize this is from 2012. It is in my recent topics thread for some reason. Whoops!

[Anonymous]

I tried to ask my genetic counselor about the frequency of other disorders, since I agree with OP, this would be the main reason to do a CVS or amnio instead of screening in the absence of other concerns (except AMA).

My counselor actually did not know the answer to this question and had to look it up. She came back a week later saying that among women 35+ the chances of finding detectable chromosomal problem that is not a trisomy or missing sex chromosome was on order 1% with 0.7% being "clinically significant." I think these include chromosomal truncations and translocations. They can vary in severity but some potential problems include infertility and intellectual disability.

I decided based on this information to do a CVS, but honestly I wish I'd asked more. And thought about it more. Questions I had: how severe would such disabilities be? Could they tell from the CVS results? And for me, not them, had I found such a thing, what would I have done about it?

I don't know the answers to these questions. I recommend you see a genetic counselor (hopefully better than mine was, I found her really hard to talk to about numbers, and I'm a statistician by profession so this was really annoying, but maybe an unfair standard of mine) and get the answers you want. If you do, please report back. Oh, and I hope everything goes well and this information is moot for you.