There are several different kinds of preimplantation genetic embryo testing. Costs vary depending on the type of test, but the cost starts at around $3,900.All tests use a biopsy of the embryo to check for either the number of chromosomes or a gene mutation.The PGS, preimplantation genetic screening, checks that all 46 chromosomes are there (including the two sex chromosomes). The PGD test is used to look for a potential known single gene defect that is present in the families of the parents.Remember that the chromosomes are the containers of all the genetic code for a baby, which is a lot of information! A useful way to think of chromosomes is to think of them as books. So, in some cases a more specific test that opens the book and looks for a specific gene may be warranted.PGT, preimplantation genetic testing, is a new term for both the PGS and PGD tests. The type of type is denoted with a suffix. For example, PGT-A checks the number of chromosomes. It also detects which sex chromosomes the embryo has (X and X, or X and Y). PGT-M checks for a gene mutation.