A great overview, thanks for writing it! I think it will help a lot of people. I suggest a few corrections though:
That unbelievable, super exponential drop was made possible by a technology called “Next Generation Sequencing”.
By the mid-2010s, you could sequence all the parts of a person’s genome most likely to differ from other people’s for under $100.
SNP genotyping doesn’t use next generation sequencing, it uses microarrays. (Also it’s more properly called genotyping not sequencing)
This is very fortunate for us because these cells contain a treasure trove of information. The most common thing IVF clinics look for is aneuploidy, which is a medical term meaning “this embryo has an abnormal number of chromosomes”. The term for this type of testing is “PGT-A”, and it’s performed in roughly half of all IVF cycles in the US today.
Human embryos with the wrong number of chromosomes are surprisingly common, both among IVF patients and natural births. But this wasn’t very well understood before the first use of pre-implantation genetic testing in the late 1980s.
I should note, in some cases embryos with aneuploid cells in the trophectoderm actually have a mixture of aneuploid and euploid cells, and the euploid cells can successfully grow into a healthy embryo. So an aneuploid trophectoderm biopsy doesn’t necessarily mean the embryo is not viable. (Although it does provide some evidence for that.)
A great overview, thanks for writing it! I think it will help a lot of people. I suggest a few corrections though:
SNP genotyping doesn’t use next generation sequencing, it uses microarrays. (Also it’s more properly called genotyping not sequencing)
I should note, in some cases embryos with aneuploid cells in the trophectoderm actually have a mixture of aneuploid and euploid cells, and the euploid cells can successfully grow into a healthy embryo. So an aneuploid trophectoderm biopsy doesn’t necessarily mean the embryo is not viable. (Although it does provide some evidence for that.)
Thanks for the correction
Sorry I may have deleted your response to my mosaicism comment when I merged it with this one. I agree that it’s controversial.