The Free DNA Fetal Kit RhD is used to determine the fetal Rhesus D (RhD) genotype by using cell-free fetal DNA from a maternal blood sample of a RhD negative pregnant women.
Key Benefits
- Fetal genotyping using exons 5, 7 and 10, ensuring the detection of a wide range of RhD variants
- Sensitivity of 100%; no false negatives
- IVDR certified
- Non Invasive prenatal testing (NIPT)
Features
- 96 tests per kit, which can be run in 1 to 6 runs, adapting to your workflow and capacity
- Ideal for both routine diagnostics and high-throughput laboratories.
- Determination from the 11th week of pregnancy
- Validated on the most commonly used automated platforms
- Positive and negative controls included
Applications
- Determination of fetal RhD to avoid systematic and unnecessary injections of anti-D immunoglobulins
Introduction
Determination of the fetal RhD genotype in RhD negative pregnant women is essential for obstetric management. Rhesus incompatibility occurs when an RhD-negative mother is carrying an RhD-positive fetus. Without proper management, this can lead to the development of maternal antibodies (alloimmunization) that may affect current or future pregnancies.
RhD alloimmunization is responsible for severe fetal and neonatal anemias, as well as severe neonatal jaundice. In RhD negative women, it corresponds to the synthesis of IgG RhD antibodies in response to the transplacental passage of RhD positive fetal red blood cells into the maternal circulation. Maternal antibodies crossing the placenta into the fetal circulation cause hemolysis and anemia in the RhD-positive fetus. Alloimmunization can be prevented by administering anti-D immunoglobulins.
The knowledge of fetal RHD genotype status is essential in:
- non-immunized RhD negative women to identify those who should receive immunoprophylaxis.
- RhD negative women who have already been immunized, to identify fetuses at risk of anemia (RhD positive fetuses) who should be specially monitored.
By targeting only RhD-positive pregnancies for prophylaxis, the test:
- Prevents unnecessary exposure to anti-D immunoglobulin
- Preserves resources
- Protects the health of both mother and fetus
Principle of the Free DNA Fetal Kit RhD test
It has been shown that the plasma of a pregnant woman contains traces of circulating cell-free fetal DNA (cffDNA) in low concentrations that increase with gestational age. This DNA is equivalent to a few to several hundred copies of the fetal genome per ml of plasma. In RhD negative pregnant women who do not have the RhD gene in their genome, the detection of RhD gene sequences in plasma indicates that the fetus has an RhD positive genotype. Conversely, failure to detect RhD gene sequences indicates that the fetus has an RhD negative genotype.
The Free DNA Fetal Kit RhD is a test consisting of 2 multiplex real-time PCRs designed to detect 3 distinct regions specific to the RhD gene: exons 5, 7 and 10 in maternal plasma in order to detect as many RhD gene variants as possible. In each well, two amplification reactions were performed using DNA extracted from the test samples:
- Well 1 : a specific reaction for exon 5 of the RhD gene and a specific reaction for internal control DNA.
- Well 2: a specific reaction for exon 7 of the RhD gene and a specific reaction for exon 10 of the RhD gene.
The accumulation of specific amplification products is revealed by specific TaqMan® hydrolysis probes labelled with the fluorophore FAM for exon 5 and exon 7 of the RHD gene and with the fluorophore HEX for exon 10 of the RhD gene and the internal control (IC; maize DNA).
The procedure is as follows:
- Maternal blood sample is taken
- Cell-free fetal DNA (cffDNA) is extracted (materials not included in the kit) and analyzed
- The presence or absence of RHD exons determines the fetal RhD status
- Results indicate whether the fetus is RhD-positive or RhD-negative
Please contact us to receive the instructions for use of the Free DNA Fetal Kit RhD