Also known as cell-free DNA (cfDNA) screening,noninvasive prenatal testing (NIPT) is a prenatal aneuploidy screening test.
WHAT WILL YOU GAIN WITH AN EXPANDED NIPT SCREEN? MORE INSIGHTS.
Fetal chromosome abnormalities aren’t limited to 3 common trisomies. Why should your screening be?
Prenatal screening for trisomies 21, 18, and 13 has been available for over 30 years. The narrow focus on these 3 aneuploidies was due to test limitations, not because they were the only known chromosomal abnormalities.
With cell-free DNA (cfDNA)–based prenatal testing, also called noninvasive prenatal testing (NIPT), we can use expanded screening to obtain a comprehensive view of all 23 chromosome pairs while limiting the risk to your patient.
Sample Prep
First, plasma is isolated from whole blood for cfDNA extraction.
Then, utilizing all available cfDNA, the whole-genome and PCR-free approach, maximizes efficiency and robustness of the assay, as demonstrated by the lowest failure rate among in-lab solutions.
Lastly, uniquely tagging the fragments from each sample using adapters
Sequencing
The ends of each fragment are sequenced using 2X36 bp reads.
These paired-end reads are aligned to the genome, contextually providing the length of each fragment (measured by the distance between the two paired reads).
Fragment length is valuable because shorter cfDNA fragments are more likely to be fetal in origin, while longer cfDNA fragments are more likely to be maternal in origin.
Analysis and Reporting
A dynamic threshold individually assesses the quality and quantity of the collected reads for each sample to determine if there is enough information to make a call.
If so, these reads are sorted by chromosomes to look for deviations from the expected distribution.
By focusing on shorter fragments, there is an increase in relative fetal signal, allowing excellent results without a fetal fraction cutoff.