NIPTIFY is based on analysis of cell-free DNA from maternal blood. Most of the cell-free DNA in maternal blood has maternal origin and a smaller fraction (5-20%) has foetal origin. NIPTIFY analyses the amount of cell-free DNA and detects chromosomes in high confidence that are in an abnormal copy number. For example, if chromosome 21 is in three copies (causing foetus Down syndrome), the software finds it from maternal blood sample.
The origin of all foetal cell-free DNA is unknown, but most of it comes from placental cells that surround the foetus and are genetically of foetal origin. Foetal cell-free DNA can already be found in maternal blood plasma from week 4 of pregnancy. By week 10, when the foetus is a bit bigger than a ping-pong ball, the foetal cell-free DNA fraction in maternal blood plasma is already 4-5%. This amount is sufficient for NIPT analysis.
The fetal cfDNA fraction rises during pregnancy. When it is too low, NIPTIFY analysis is complicated. That is why the earliest time to perform the NIPTIFY test is the beginning of pregnancy week 11.
The time from foetal cfDNA being released from the placental cells to it being broken down in the liver and kidneys is called half-life. The half-life of cfDNA is short and already a couple of hours after giving birth it cannot be detected from the maternal blood anymore. That means previous pregnancies do not affect the test results for the current pregnancy.
Unique data analysis
cfDNA is analysed using a highly accurate DNA sequencing technology – Illumina technology. This technology is modern and widely used in scientific and medical research as well as in diagnostics. NIPTIFY is a state-of-the-art medical service, combining advanced technologies with sensitive data analysis.
The innovative NIPTIFY data analysis software is called NIPTmer. This unique software is developed in Estonia and assesses whether the foetus has chromosomes in normal copy number or not. Below is a diagram about DNA sequencing technology and the principle of how a trisomy is found.
Another unique software is used to calculate the foetal cell-free DNA fraction in the maternal blood sample. Using contemporary machine learning methods, it is possible to find patterns in DNA that tell us whether the foetus is big enough for the analysis and whether the NIPTIFY test result is trustworthy.