Dr. Anne GIRARDET
( MCU-PH, Ph.D. )
The intented goal of preimplantation genetic diagnosis (PGD) is to diagnose a specific genetic disease on single cells from embryos obtained through an in vitro fertilization (IVF) procedure, by selecting and transferring to the woman’s uterus only embryos found to be unaffected, before a clinical pregnancy has been established. Genetic diagnosis is performed on one or two blastomeres biopsied from 3 days-old embryos, then embryos free of the disease under investigation are transferred to the mother on day 4 or 5.
For some couples at high risk of transmitting a genetic disorder to their offspring, PGD is an alternative approach to conventional prenatal diagnosis (PND) as it avoids the emotional burden associated with termination of pregnancy.
Most of couples seeking PGD already have an affected child, have lost affected children due to the genetic condition and wish to avoid further risk, and/or have experienced repeated elective therapeutic abortion of an affected fetus. Until recently, couples at risk who wished to prevent the birth of an affected child could remain childless, opt for a spontaneous pregnancy with prenatal diagnosis and termination of pregnancy if the fetus was shown to be affected, choose gamete donation or adoption.
For all couples requesting PGD, the disease-causing mutation must have been previously identified. According to the french law, only this genetic abnormality as well as linked markers may be studied.