Preimplantation Genetic Testing (Including Preimplantation Genetic Diagnosis and Preimplantation Genetic Screening)
What is preimplantation genetic testing (PGT)?
Your embryos can be tested for abnormal chromosomes before they are transferred to the uterus. This is called preimplantation genetic testing, or PGT. It is done in a lab, using in vitro fertilization (IVF). One or more cells from each embryo are sent for genetic testing. Genetically healthy embryos are transferred to the uterus, where they may attach to its lining and produce a pregnancy.
What genetic tests can be performed?
Cells from the embryo can be tested for a gene that may produce a specific disease. This will show if an embryo is normal (no disease) or affected (has the disease). It will also show if the embryo is carrying the disease but unaffected by it. An unaffected carrier is someone who can pass the disease to his or her children but does not personally have any signs of the disease.
A karyotype is another kind of genetic test that can check the chromosomes. It is done during pregnancy, either by a chorionic villus sampling or amniocentesis. This test shows if the fetus has more or fewer chromosomes than the usual 46.
Having too many or too few chromosomes can cause disorders such as Down syndrome (Trisomy 21) or Trisomy 13. This test can also look for out-of-order chromosomes, called translocations, which can cause problems with growth or function.
The number of genetic testing for heart problems keeps growing every year.
What is a preimplantation genetic diagnosis (PGD)?
PGD involves testing an embryo before it implants for a specific, known genetic disorder. PGD is used so that embryos unaffected by the disorder can be returned to the uterus.
Part 2 of this article will be published tomorrow.
This article is from the American Society for Reproductive Medicine and originally published on their website at https://www.asrm.org/FACTSHEET_Preimplantation_genetic_testing/
RSMC preforms PGD and PGS and the results are analyzed in our onsite lab. For more information, please e-mail firstname.lastname@example.org.