Tuesday, January 07, 2014

The problem with PGS/CCS - more is not always better

Most doctors have an abiding faith in medical technology and naively believe that science can solve all problems. This is why so many IVF specialists are now actively pushing CCS ( comprehensive chromosomal screening) for all IVF patients.

Admittedly, it's hard to argue with them, because their logic is so seductive. After all, if we can use whole genomic sequencing to exclude genetically abnormal embryos,   then isn't it logical that  the transfer of genetically normal embryos will improve pregnancy rates ?

However, biology doesn't always fall in line with human logic ! There are 3 flaws with this reasoning.

1. These tests cannot pick up all genetic problems ( because our technology is not good enough to do so as yet). Just like the older FISH technology had limitations, CCS has its limits too ( which doctors don't talk about)

2. Embryos are alive and can self-correct their genetic errors . This means that the rationale for testing itself is flawed

3. The tests will provide lots of false positive results, which will cause doctors to discard embryos which could have given rise to completely healthy babies ! There are lots of grey areas , which doctors conveniently gloss over by labelling the test results as being "inconclusive".

Sadly, most IVF specialists understand very little about genetics - and very few are honest enough to accept this. Now , I am not a Luddite, but I think we need to do a lot more research before offering CCS on a routine basis to all IVF patients. Patients are very emotionally vulnerable, and it's very easy to convince them to say yes to anything we tell them to, but this is often not in their best interests. The trouble is that doctors like offering the "latest" services because these are cutting edge !  They need to show they are better than the other doctors . This means that there's a lot of oneupmanshipat play - and huge financial stakes as well !

A very sensible article at Virtual Mentor discussed the ethics of CCS. This is what they concluded.
" One can only surmise, however, that more intense genetic analysis of embryos is likely to show multiple variants of uncertain significance ( VOUS) , and all the counseling needed for prenatal testing will need to be made available, and perhaps even expanded, for patients considering having embryos’ genomes sequenced. Will finding VOUS lead to discarding healthy embryos? "


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