Noninvasive prenatal diagnosis using fetal DNA in maternal plasma: from digital PCR to next-generation sequencing

Abstract
Prenatal diagnosis is now an established part of modern obstetrics care. However, conventional definitive methods for prenatal diagnosis, such as amniocentesis, are typically invasive and constitute a risk to the fetus. In 1997, our group reported that cell-free fetal DNA is present in the plasma of pregnant women. This technology has initially been used to detect paternally-inherited fetal genetic characteristics, e.g. sex and blood group genes that are absent in the mother. In 2007, our group reported the use of digital PCR for the precise quantitative analysis of fetal DNA in maternal plasma. We demonstrated the theoretical and practical basis for single molecule analysis for the noninvasive prenatal diagnosis of trisomy 21. We have since demonstrated that massively parallel sequencing is a robust method for the noninvasive detection of fetal trisomy 21 and have recently reported a large scale study using this technology. Our results indicate the fetal trisomy 21 can be detected with a sensitivity of 100% and a specificity of 98% using this technology. We have also recently shown that in addition to trisomy 21, maternal plasma DNA sequencing can also reveal the genome-wide genetic map of the fetus. Thus, massively parallel sequencing is likely to play an increasingly important role in the future prenatal diagnostics and monitoring.