The IONA® test directly measures the change of DNA levels in the maternal plasma when fetal trisomy 21, 18 or 13 is present. During pregnancy, the placenta leaks cell-free DNA into the maternal bloodstream. As a result, a maternal plasma sample contains a mixture of placental DNA and maternal DNA.
The IONA® test directly measures the amount of cell-free DNA and can detect small changes in the DNA ratio between the cell free maternal and fetal DNA when a fetal trisomy 21, 18 or 13 is present. The IONA® Software for analysis calculates the relative amount of chromosomes 21, 18 and 13 to calculate a risk score. The risk score and prior risk (maternal age) is used in the algorithm to provide a probability (risk) of the fetus being a trisomy 21, 18 or 13.