DPI: what you need to know


What is pre-implantation diagnosis?

The DPI offers the possibility for a couple to have a child who will not have a genetic disease that could be transmitted to him. 

PGD ​​consists of analyzing cells from embryos resulting from in vitro fertilization (IVF), that is to say before they even develop in the uterus, to then rule out those affected by a genetic disease or chromosomal precise.

How does the pre-implantation diagnosis work?

At first, as with a classic IVF. The woman begins with ovarian stimulation (by daily injections of hormones), which makes it possible to obtain more oocytes. They are then punctured and brought into contact with the spouse’s sperm in a test tube. It was not until three days later that the pre-implantation diagnosis really took place. Biologists take one or two cells from embryos (with at least six cells), in search of the gene related to the disease sought. Then the IVF is continued: if one or two embryos are unharmed, they are transferred to the maternal uterus.

Who is the pre-implantation diagnosis offered to?

Le Preimplantation genetic diagnosis (or PGD) is a technique which makes it possible to detect possible abnormalities – genetic or chromosomal – in embryos conceived after in vitro fertilization (IVF). It is proposed couples who are at risk of passing a serious and incurable genetic disease to their babies. They may themselves be sick or just healthy carriers, that is, they carry the gene responsible for the disease, but are not sick. This gene is sometimes not discovered until after the birth of a first sick child.

PGD: what diseases are we looking for?

Most commonly, these are cystic fibrosis, Duchenne muscular dystrophy, hemophilia, Steinert myotonic dystrophy, fragile X syndrome, Huntington’s chorea, and chromosomal imbalances associated with translocations, but there is no exhaustive list. has been defined. The judgment is left to the doctors. In addition, there is not yet a diagnostic test on embryonic cells for all genetic diseases serious and incurable.

Where is the pre-implantation diagnosis performed?

In France, only a limited number of centers are authorized to offer PGD: the Antoine Béclère hospital, the Necker-Enfants-Malades hospital in the Paris region, and the Reproductive Biology Centers present in Montpellier, Strasbourg, Nantes and Grenoble.


Are there any examinations prior to the pre-implantation diagnosis?

In general, the couple has already benefited from genetic counseling which referred them to the PGD center. After a long interview and a thorough clinical examination, the man and the woman must undergo a rather long and restrictive battery of tests, identical to that which must follow all the candidates for a technique of medically assisted procreation, because there is no PGD possible without in vitro fertilization.

PGD: what do we do with the other embryos?

Those affected by the disease are immediately destroyed. In the rare event that more than two good-quality embryos are unharmed, those that have not been implanted (to limit the risk of multiple pregnancies) may be frozen if the couple expresses a wish to have more children.

Are parents sure that they will have a healthy child after PGD?

PGD ​​only looks for a specific disease, for example cystic fibrosis. The result, available in less than 24 hours, therefore only confirms that the future baby will not suffer from this disease.

What are the chances of pregnancy after a pre-implantation diagnosis?

Overall, they are 22% after a puncture and 30% after embryo transfer. That is to say, roughly identical to those of a woman being spontaneously pregnant during a natural cycle, but the results vary according to the quality of the oocytes and therefore the age of the mother. wife.

Is it also used to select “medicine babies”?

In France, the bioethics law authorizes it only since December 2006, but only when a first child has an incurable disease which requires a bone marrow donation if there is no compatible donor in his family. His parents can then consider, with the agreement of the Biomedicine Agency, to have recourse to PGD to select an embryo free from the disease and in addition compatible with the sick child. A strictly supervised process.

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