GSN vs 2, 5, 9 - probe

[nancy]

Hi Dr. Potter,

I will be cycling with you in August. You recommended GSN for me (I am on the long lupron protocal, age 38 and doing GS for a girl). I am very excited about this relatively new technology but feeling a little apprehensive as well. There have been mixed comments about GSN vs. FISH (2,5,9-probe) on this board. I have a few questions below that I hope you will not mind answering. If it is easier to speak on the phone w/yourself or Lori please let me know.

1. I was wondering if you will still recommend GSN for me if I have 10 or less healthy embryos to work with?

2. There has been concern that since GSN tests a single cell on day three that it isn't the most reliable method of testing compared to day 5 w/FISH. Can you provide me with reassurance that it in fact is?

3. You posted on another thread that 5-probe "With FISH (2, 5 or 9 probe), you are looking at around 50% of the embryos that are thought to be normal actually having abnormalities in one or more of the chromosomes that have not been checked". How often does this scenario happen with woman my age who do not have a history of inherited genetic diseases or any fertility issues? My main concerns are preventing downs, trisomy, etc...

4. Are you seeing more successful pregnancies achieved w/FISH (2, 5 or 9 probe) or GSN?

5. Lastly, I would like some reassurance about 24 chromosome testing since it is a relatively new technology. Since you are the lab director at GSN, I am hoping this means you work w/the same highly trained staff on a regular basis who are experts with this?

Thank you in advance for your response! I am really looking forward to hearing from you!

[mis2ninos]

Great questions did dr potter let you choose between a 3 day or 5 day gsn or does he only do 3 day? Tia

[nancy]

We haven't spoken about that mis2ninos so not sure what the answer is yet.

[Dr. Potter]

Hi Dr. Potter,

I will be cycling with you in August. You recommended GSN for me (I am on the long lupron protocal, age 38 and doing GS for a girl). I am very excited about this relatively new technology but feeling a little apprehensive as well. There have been mixed comments about GSN vs. FISH (2,5,9-probe) on this board. I have a few questions below that I hope you will not mind answering. If it is easier to speak on the phone w/yourself or Lori please let me know.

1. I was wondering if you will still recommend GSN for me if I have 10 or less healthy embryos to work with?

2. There has been concern that since GSN tests a single cell on day three that it isn't the most reliable method of testing compared to day 5 w/FISH. Can you provide me with reassurance that it in fact is?

3. You posted on another thread that 5-probe "With FISH (2, 5 or 9 probe), you are looking at around 50% of the embryos that are thought to be normal actually having abnormalities in one or more of the chromosomes that have not been checked". How often does this scenario happen with woman my age who do not have a history of inherited genetic diseases or any fertility issues? My main concerns are preventing downs, trisomy, etc...

4. Are you seeing more successful pregnancies achieved w/FISH (2, 5 or 9 probe) or GSN?

5. Lastly, I would like some reassurance about 24 chromosome testing since it is a relatively new technology. Since you are the lab director at GSN, I am hoping this means you work w/the same highly trained staff on a regular basis who are experts with this?

Thank you in advance for your response! I am really looking forward to hearing from you!Here are the answers to your questions. I hope that they are helpful.

1. GSN is better technology and gives you the truth about your embryos. When I recommend FISH, it is only in cases where spending the extra money on GSN is not going to help us. GSN is never going to hurt you compared to FISH. It is just that if you have 2 or 3 embryos to biopsy, it is not likely that the embryo selection advantage you get with GSN is going to change the outcome and justify the increased cost. I would say the cutoff is 4-5 embryos available to biopsy.

2. The false postive rate is 10x lower with GSN that with FISH. Day 3 GSN is going to be more accurate than day 5 FISH. FISH is particularly ill-suited for day 5 PGD. Day 5 PGD should only be done with either GSN, cCGH or possible sequencing techniques in my opinion. What we have recognized with day 3 biopsy is that there are certain types of abnormalities that have a chance to represent mosaicism and the embryo has a chance to actually test normal on day 5. These include simple aneuploidies from the paternal origin, deletion/duplications. So we will selection certain embryos for re-biopsy on day 5 that we feel have a chance. It is important to note that even in this higher risk group, the vast majority of the cases confirm the original result. So, choosing between day 3 GSN 24 and day 5 FISH is no contest; choosing between day 3 vs. day 5 GSN 24 is in favor of day 3 now but could shift if we have the ability to do fresh transfers with GSN on day 5.

3. That is correct, even for those without a history. Aneuploidy rates are purely age related and only rarely have any familial tendency. At 38, the rate of aneuploidy is actually higher than 50%, probably closer to 70%.

4. The implantation rate per embryo transferred is about 40% higher with GSN than FISH in my experience.

5. I do work as the lab director for GSN. I am a huge proponent of 24 chromosome screening of embryos prior to IVF. GSN is simply the most accurate technology currently available to do this but not the only technology. You are better of with aCGH than FISH as well.

[nancy]

Thank you!