Noninvasive Cell-Free DNA Prenatal Testing for Fetal Aneuploidy in Maternal Blood

Many researchers have attempted to develop noninvasive prenatal testing (NIPT) methods in order to investigate the genetic status of the fetus. The aim is to avoid invasive procedures such as chorionic villus and amniotic fluid sampling, which result in a significant risk for pregnancy loss. The discovery of cell-free fetal DNA circulating in the maternal blood has great potential for the development of NIPT methodologies. Such strategies have been successfully applied for the determination of the fetal rhesus status and inherited monogenic disease, but the field of fetal aneuploidy investigation seems to be more challenging. The main reason for this is that the maternal cell-free DNA in the mother's plasma is far more abundant and is identical to half of the corresponding fetal DNA. Methodologies developed are mainly based on counting DNA sequences via next-generation sequencing and microarray-based methodologies. Genetic services for noninvasive fetal aneuploidy testing serve as screening tests. The pace of NIPT is unprecedented in clinical laboratory medicine, and fetal aneuploidy NIPT appears to be the most rapidly adopted genomic test. There have been rapid advances in fetal genomic analyses from maternal plasma, and this will hopefully translate equally rapidly to advances in patient care. In the present chapter we discuss the use of NIPT strategies and the future potential of the methods developed with the aim of eventually avoiding invasive procedures and evolving NIPT (testing) into noninvasive prenatal diagnosis.