For expectant mothers, this paves the way for targeted rhesus prophylaxis. Until now, all rhesus D-negative pregnant women were usually advised to undergo treatment with expensive and difficult to obtain anti-D immunoglobulins. However, in nearly 40% of cases, this is not necessary because the fetus is also rhesus D negative.
Thanks to our new FastQ® RHD fetal kit, targeted anti-D prophylaxis is possible by using modern, molecular and non-invasive fetal diagnostics via real-time PCR typing. If a rhesus D-positive child is expected, only a blood sample from the pregnant woman is required for the prenatal test.* Testing may be carried out from the 11th week of pregnancy at the earliest in single-child pregnancies.
The prerequisite for a reliable analysis of the fetal rhesus D trait is a sufficient amount of cell-free fetal DNA (cff DNA). Since it is possible that there is not enough cff DNA in the blood at the 11th week of pregnancy, a second test must be performed from the 20th week of pregnancy if the first result is negative. This is because the concentration of cff DNA increases during the course of pregnancy.
Due to the high number of variant RhD alleles, there are RhD variants in which individual exons may be missing. For this reason, 3 exons of the RHD gene are examined by real-time PCR analysis. By detecting the three exons 5, 7 and 10, the probability of a false negative result is extremely minimized.
* In Germany specialized genetic counseling is required for the analysis, as it is a genetic examination of a genetic trait in the unborn child.