Approche non invasive du diagnostic prénatal biologique : du génotypage rhésus D à la trisomie 21

In its conventional approach, prenatal diagnosis is based on the analysis of fetal cellular material obtained by invasive procedures such as chorionic villus sampling, amniocentesis or fetal blood sampling. In most cases, it is performed to establish the fetal karyotype in order to determine the presence of chromosomal abnormalities in the fetus. However, amniocentesis, the main worldwide invasive procedure, carries a risk of fetal miscarriage that is estimated to be around 1%. Therefore, many laboratories have attempted to develop noninvasive prenatal diagnostic procedures to avoid such fetal loss. Analysis of fetal cells circulating in the maternal blood is still not developed enough for routine use because of several technical problems. In contrast, cell-free fetal DNA, circulating in maternal plasma/serum, has rapidly become a useful tool for prenatal diagnosis. Even if this approach today is limited to fetal sex determination and rhesus D genotyping, large investigations are currently underway to develop noninvasive prenatal diagnostic techniques for fetal chromosomal abnormalities, such as trisomy 21, based on circulating fetal nucleic acids.