When a couple is likely to transmit a serious genetic disease to their future child, a preimplantation diagnosis (PGD) is possible. The goal is to "analyze" embryos obtained after IVF in order to eliminate those carriers of the disease.
Who is the preimplantation diagnosis for?
- DPI, which has been authorized since 1999 in France, is aimed at couples who risk transmitting to the fetus a particularly serious and incurable genetic disease. This may be the case for cystic fibrosis, Duchenne muscular dystrophy, a chromosomal anomaly ... When a couple applies for a CIO, a medical committee valid or not their project, depending on the chances of success, including. In France, four centers are authorized to practice this preimplantation diagnosis, in Paris-Clamart, Strasbourg, Montpellier and Nantes, since June 2013.
What is preimplantation diagnosis?
- After performing a conventional in vitro fertilization, a genetic diagnosis is made on the embryos, before they are transferred in the uterus of the woman: "Three days after IVF, we take two cells on the viable embryos to determine if they carry or not the pathology that we are looking for.This genetic diagnosis is possible because we carefully trained upstream, for many weeks, the genetic profile of the couple in relation to the familial genetic disease.If one of the embryos is unscathed, it can be implanted in the uterus, usually within 24 to 48 hours after the removal of embryonic cells Twelve days later, a blood test will confirm or not the pregnancy, "says Professor Cédric Le Caignec, geneticist at the University Hospital of Nantes. It may happen that no embryo is healthy, a second DPI will then be proposed to parents. In total, a couple can attempt four DPIs before each pregnancy.
How is PGD different from prenatal diagnosis?
- PGD and prenatal diagnosis have in common to be reserved for couples who have a risk of transmitting a serious illness to the child, but they are not realized at the same time. Prenatal diagnosis is offered to parents when the pregnancy has already begun, while PGD is performed after IVF and before implantation into the uterus. Depending on the outcome of the prenatal diagnosis, a medical termination of pregnancy may be decided by the parents. The pre-implantation diagnosis taking place before the pregnancy, it makes it possible to avoid this painful stage since the risk of transmission to the fetus is discarded "upstream".