Biomedical Engineering Reference
In-Depth Information
9
Noninvasive Prenatal Diagnosis by Analysis
of Fetal DNA in Maternal Plasma
Rossa W. K. Chiu and Y. M. Dennis Lo
Summary
Prenatal diagnosis has become a standard part of obstetrics care. Genetic diagnoses
are established prenatally through the sampling of fetal genetic material by invasive
methods such as amniocentesis or chorionic villus sampling, which are associated with a
risk of fetal loss. Hence, the recent discovery of the presence of fetal DNA in maternal
plasma has led to exciting possibilities of noninvasive prenatal diagnosis. Numerous
applications have since been reported for the analysis of circulating fetal DNA. The
accuracy of fetal DNA assessment from maternal plasma is dependent on the appropriate
preanalytical handling of maternal blood samples, an efficient fetal DNA extraction pro-
tocol, and a sensitive and specific detection method. The protocol that has been applied
regularly in the laboratory of the authors for the reliable detection and quantification of
circulating fetal DNA is presented in this chapter.
Key Words:
Fetal DNA; prenatal diagnosis; noninvasive; real-time quantitative PCR;
circulating nucleic acids.
1. Introduction
Prenatal diagnosis is an indispensable part of present-day obstetrics care.
Prenatal genetic diagnosis relies on the sampling of fetal tissues and at present
is dependent on procedures such as amniocentesis or chorionic villus sampling.
As these procedures are invasive in nature, they are associated with a small but
finite risk of spontaneous abortion. In 1997, the existence of fetal DNA in
maternal plasma was first reported and has opened up exciting opportunities
for the development of noninvasive methods for prenatal diagnosis
(
1
)
. It has
subsequently been demonstrated that significant amounts of fetal DNA are
present in maternal plasma, amounting to 3-6% of the total DNA in maternal
plasma
(
2
)
. With the adoption of sensitive molecular methods, such as real-
