Hi Debbie and Gigi![]()
I'm really hoping Gigi's baby is going to be OK and have read this thread with interest - partly due to having studied this, but not had much IRL awareness of it, but mostly because I want to be able to offer any support I can, even if it is just explaining a bit of science!
If the Amnio results are positive for Downs that may mean that the baby has Downs, or it may mean that the Amniotic fluid is a Downs fluid - sometimes a little fertilised egg can be fertilised as a Downs egg (3 C21s), but get its act together pretty quickly and kick out a spare chromosome in the early splits. I really think these bubs are so clever! However, there is part of the blastocyte that is Downs, and part that is not. Usually the "not Downs" part forms the baby and the Downs part forms part of the placenta and all of the amniotic fluid.
So if the Amino shows Downs, the CVS testing the placenta will either show Downs, not Downs, or Mosaic Downs. Mosaic Downs means the baby will have less severe Downs - if baby has Downs at all - but no Downs means the baby is fine. If the placenta is Downs then there is a good chance the baby has full-blown Down's Syndrome.
Finally, FISH - this always looked so cute in my lectures. Basically there's a C21 dye, a Y dye and an X dye (amongst others), these are popped into the cell and attach themselves to the chromosomes during a cell split, so when the sample is put under a flursecent microscope you can see all the chromosomes you're looking for. It really is clear and something great visually - if you can get these results as part of the baby/pregnancy book I'd recommend it, keep them with the baby's scans as a fantastic record. I always did more PCR than FISH - PCR is more quantitative, FISH more visual counting-to-two (or one for Y, or 3 for trisomies).
Gigi, I am really, really hoping the amnio shows no Downs. Wishing you all the best.



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