Preimplantation genetic testing

Preimplantation genetic diagnosis (PGD) is a way of checking embryo cells before they are placed, or implanted, inside a mother's body. It is also named preimplantation genetic testing (PGT). The good thing about PGD is that it can let the parents not choose the embryo which will develop into a child with a certain disease. This way, the parents do not have to choose to stop the pregnancy if the baby has the disease. To do preimplantation testing, doctors take the mother's eggs from her body. Then, the embryo is tested, and put back in the mother after 5 or 6 days of growing.

The first preimplantation testing was done by choosing a female embryo, because the disease was only possible if there was one X chromosome, such as in male embryos.

It can also test to see if the embryo has a different number of chromosomes than normal. This is called preimplantation genetic testing for aneuploidy, or PGT-A. The other types of preimplantation genetic testing are for gene (monogenic) disorders (PGT-M), for many gene (polygenic) disorders (PGT-P), for seeing if large parts of the chromosomes are improperly put together (PGT-SR).

Sometimes, tests can also be done on the mother's eggs or the father's sperm before they meet to make a baby. These can also be part of PGD.Page 205 in:  

 Related pages 
 Designer baby
 Polygenic score

Notes and references

Category:Genetics