A new approach of digital PCR system for non-invasive prenatal screening of trisomy 21.

BACKGROUND: Non-invasive prenatal screening (NIPS) of trisomy 21 (T21) using digital PCR (dPCR) with several advantages will be very effective. Here, we developed a dPCR system for T21 screening which allows high sensitivity and real-time diagnosis and thus overcome sequence based analysis.

METHODS: Cut-off value was established using DNA extracted from all 157 T21 negative samples including 47 pregnant woman samples and 3 T21 positive pregnant woman samples extracted from 4 different sample types. To increase the portion of the cell-free fetal DNA (cffDNA) in maternal cell-free DNA (cfDNA), a size selection method was devised. We evaluated the clinical reliability of NIPS using dPCR through analysis of 877 pregnant woman samples.

RESULTS: We could demonstrate the possibility of NIPS using dPCR performed by applying cut-off value and size selection method. The overall accuracy was derived at 99.66% using 877 pregnant woman plasma samples.

CONCLUSION: Our results showed that dPCR can meet the requirements for NIPS for T21. It is relatively inexpensive, easy to use in a screening method and compatible with ethical concerns regarding access to nucleotide sequence information. This study may be a basic data for the development of population-wide screening for T21 in pregnant women.