Can we discuss 24 probe or 2 probe PGD?

Sassafras:

Thanks for posting this Lillylolly!  I am having trouble with this same decision.  It seems that the 24 probe GSN sounds better, but the 2 probe is more "tried and true".

 So has anyone used the 24 probe GSN at HRC?  I'd just hate to be the first, or to use a technology that is less likely to be successful b/c it is new.  But, I like the idea of knowing that all the chromosomes are normal.  Is anyone planning to do 24 GSN at HRC?

 Has anyone done 2 probe and then regretted not doing more probes?  I'm so confused.  I think I just want my cake and eat it too...I want all the probes, but not the risk of no transfer or affecting the ability to become pregnant.

Ugh...so many decisions...

They have had trials with it so they have seen some sort of results and obviously, they believe it is the better option.  Here is where the 2-probe can hurt- if you end up with 10 embryos that are the right gender on day 5, transfer 2 and BFN, you might have to do that a couple of times to find the right one.  That or if you find out the baby has something that they could have screened for and then you have to deal with that.  So, there is definitely something to be said for looking at everything the first time and if you end up with one to transfer after GSN, I would think you have a great shot at it working!

When I had my initial consult with Dr Potter two months ago, he was pushing for 24. Then this week I had to decide what I am paying for and I talked to Lori and she said something along the lines of "since you are 29, Dr Potter thinks a 2-probe is sufficient in your case". Go figure.

I decided to go with a 2-probe. If I were over 35, I would definitely be getting a 24-probe.

Ilovemykids:

The 2 probe is still FISH, with a 10% rate of false-positives

ILMK, I'm confused and scared by this statement. The 2-probe only looks at the two sex chromosomes and gives you are 99.9% guarantee of gender. Then how can one state that the 2-probe has a 10% error rate?

If one does a 5-probe FISH for chromosomes 13,18, etc. - then yes, there is a 10% false-positive rate per probe, I understand that. But the 2-probe for X and Y is virtually 100% correct, isn't it?

I'm doing GSN 24 chromosome screening, and I will have some results to post here in a few days. When I had my consult with GSN, they said they usually see about a 50% abnormal rate. We'll see. 50% seems consistent to what I've seen on this board with people using FISH.  

blue_or_pink:

When I had my initial consult with Dr Potter two months ago, he was pushing for 24. Then this week I had to decide what I am paying for and I talked to Lori and she said something along the lines of "since you are 29, Dr Potter thinks a 2-probe is sufficient in your case". Go figure.

I decided to go with a 2-probe. If I were over 35, I would definitely be getting a 24-probe.

Very interesting.  I am 29 right now, but I will be a newly turned 30 year old when/if I cycle.  I wonder what he would suggest for me.

blue_or_pink:

Ilovemykids:

The 2 probe is still FISH, with a 10% rate of false-positives

ILMK, I'm confused and scared by this statement. The 2-probe only looks at the two sex chromosomes and gives you are 99.9% guarantee of gender. Then how can one state that the 2-probe has a 10% error rate?

If one does a 5-probe FISH for chromosomes 13,18, etc. - then yes, there is a 10% false-positive rate per probe, I understand that. But the 2-probe for X and Y is virtually 100% correct, isn't it?

 

Yes, you are correct. 

nuthinbutpink:

blue_or_pink:

Ilovemykids:

The 2 probe is still FISH, with a 10% rate of false-positives

ILMK, I'm confused and scared by this statement. The 2-probe only looks at the two sex chromosomes and gives you are 99.9% guarantee of gender. Then how can one state that the 2-probe has a 10% error rate?

If one does a 5-probe FISH for chromosomes 13,18, etc. - then yes, there is a 10% false-positive rate per probe, I understand that. But the 2-probe for X and Y is virtually 100% correct, isn't it?

 

Yes, you are correct. 

There is not a 10% error rate in determining gender with FISH - that's not what I was saying.  My understanding is there is a 10% chance of a "false positive" with FISH, meaning that FISH shows a chromosomal abnormality in an embryo when, in fact, the embryo is normal. When just doing 2 probe that would mean (I think) they see an extra or missing X or Y chromosome, for example, and the embryo is determined to be abnormal.  Sorry for the confusion.

 ETA:  If you look in GreenZelda's blog she lists her 2 probe results and you can see that there were a few embryos deemed to be "abnormal" because they were XXX or just one X.  That's different than saying an embryo is XX when in fact it is XY - that would be a true "error" which does not happen 99% of the time!  So don't worry!  You're fine!

Ilovemykids:

There is not a 10% error rate in determining gender with FISH - that's not what I was saying.  My understanding is there is a 10% chance of a "false positive" with FISH, meaning that FISH shows a chromosomal abnormality in an embryo when, in fact, the embryo is normal. When just doing 2 probe that would mean (I think) they see an extra or missing X or Y chromosome, for example, and the embryo is determined to be abnormal.  Sorry for the confusion.

 ETA:  If you look in GreenZelda's blog she lists her 2 probe results and you can see that there were a few embryos deemed to be "abnormal" because they were XXX or just one X.  That's different than saying an embryo is XX when in fact it is XY - that would be a true "error" which does not happen 99% of the time!  So don't worry!  You're fine!

Oh, I see. I did know about this, but completely forgot. Thanks, this makes sense.