Preimplantational Genetic Testing is an enormous aid to the practice of reproductive medicine since it enables detection of embryos with genetic and chromosomal alterations, thus preventing miscarriages and transmission of significant diseases, such as cystic fibrosis, thalassemias, dystrophies, etc., to our children.
Either of the future parents is a symptomatic or asymptomatic carrier of a genetic disease or of any chromosomal abnormality.
The woman is carrier of a disease linked to the X chromosome.
A couple with gynecological history of recurrent miscarriage, implantation failure or advanced maternal age
Family history
If either of the parents has an illness
The PGT study can only be conducted on embryos created by in vitro fertilization. Moreover, it is important to have a good number of embryos, since the abnormal ones will be disposed of after the study and only those diagnosed as normal for the purpose of the study will be transferred.
For conducting the PGT, it is better that the embryos are cultivated until the blastocyst stage, which is attained on the 5th-6th day after fertilization. This is the moment when the embryo reaches an internal cellular mass that will develop to form the fetus, as well as another external layer called trophectoderm, which will go on to form the placenta. The Embryo Biopsy is conducted on the latter.
Embryo Biopsy is the technique that permits making a small orifice in the trophectoderm of the embryo to aspirate 4-5 cells with a micropipette. Since these cells will develop to form the placenta, if the technique is carried out properly, it should not affect the development of the fetus. Once the biopsy has been carried out, the embryo is vitrified or transferred after learning the result of the study.
Study of the embryo
The biopsy samples of all embryos are studied in
the genetics laboratory according to the couple’s
indication.
Once the study is concluded, the laboratory issues a report that indicates which embryos are transferable and which are not.
Thanks to Preimplantational Genetic Testing, we can prevent well-known diseases, such as Down syndrome, as well as many so-called rare diseases, and even some types of inherited cancer.
At the Juana Crespo Clinic we have a PGT laboratory staffed by professionals experienced in the study of the embryo. All of this has made us one of the clinics with the highest success rate using this technique.
Types
of PGT
The PGT-A or Preimplantational Genetic Test for Monogenic Aneuploidy tells us whether the number of chromosomes of an embryo is correct. This study is carried out in women of advanced maternal age, in couples with karyotype alterations, in patients with recurrent miscarriages or prior interruptions due to chromosomal alterations. When carried out due to a karyotype alteration in the patients, the study is also called PGT-SR or PGT for structural reorganization.
The PGT-M or Preimplantational Genetic Test for Monogenic Diseases is carried out to detect any possible genetic monogenic disease in the embryo before implanting it.
The PGT-M tells us whether the embryo has a known disease produced by alteration in a specific gene. This study is conducted on patients with a hereditary disease (in the partner or in their family), or on patients with a matching compatibility test for the same disease in order to prevent transmitting the disease to their children. To conduct this type of test on embryos, first it is absolutely necessary to conduct an Informativeness Study, which consists of genetic testing of the couple and their family members in order to obtain more information on the disease and validate the diagnostic possibilities in future embryos.
