Germline Fetal RhD Blood Group Genotyping
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Non-invasive fetal RhD screening

Cell3 Direct: Rhesus D Fetal Blood Group Genotyping kit

A simple and quick qPCR protocol requiring no cffDNA extraction, Cell3 Direct offers non-invasive fetal RhD diagnosis from plasma samples.

Results in under three hours

Fast turnaround time taking under three hours from sample receipt to result as; cell-free fetal DNA (cffDNA) extraction is not required and there is a straightforward qPCR protocol.

Less material required

Using less than <0.25 ml of plasma sample, this test leaves plenty of sample for other prenatal tests.

Flexible and fully validated

A validated kit and flexible tube format enables laboratory processing on any qPCR machine.

Multi-target assay

A multi-target approach delivers an assay suitable for all populations and intra-assay concordance for increased sensitivity.

Non-invasive fetal Rhesus D (RhD) blood group testing

Non-invasive prenatal testing (NIPT) of cell-free fetal DNA (cffDNA) in maternal blood during pregnancy can be used to determine fetal Rhesus D blood group status. This means that RhD negative pregnant women can avoid receiving antenatal anti-D immunoglobulin if they are carrying a RhD negative baby and are not at risk of Hemolytic Disease of the Fetus and Newborn (HDFN).

Current practice is to provide antenatal anti-D prophylaxis at 28-30 weeks gestation, which means that about 40% of healthy RhD-negative pregnant women are exposed to a pooled human blood product that they do not need as their baby is also RhD negative.1

The Cell3 Direct: Fetal RhD Blood Group Genotyping kit predicts fetal RhD status with high accuracy, not only improving care for RhD-negative women, but allows health services to apply a targeted approach to anti-D prophylaxis and conserve the use of an expensive product that can be in short supply.

A 'direct from plasma' option for fetal RhD testing

Nonacus have developed the first commercially available, direct from plasma, non-invasive prenatal diagnosis (NIPD) kit for fetal RhD genotyping.

With no cffDNA extraction required and a simple real-time qPCR protocol, the Cell3 Direct: Fetal RhD Blood Group Genotyping kit delivers results direct from plasma in under three hours reducing technician time and providing a quicker, more cost-effective assay than previously available.

If, however, you already have high-throughput processing for extracted cffDNA set up in your laboratory or you are testing at 10-11 weeks when you need to maximize sensitivity, the Cell3 Direct: Fetal RhD Genotyping kit can still be used with extracted cffDNA.


Meets NICE guidelines on fetal Rhesus D status

Non-invasive prenatal testing to identify fetal Rhesus D status is recommended by NICE for pregnant women who are Rhesus D negative as a cost-effective option to guide antenatal prophylaxis with anti-D immunoglobulin (anti-D Ig) within the UK NHS.2

The Cell3 Direct: Fetal RhD Blood Group Genotyping kit meets all of the NICE requirements for this test.

Multi-target approach for a multi-ethnic assay

There are now known to be several genetic causes for an RhD-negative phenotype, and these vary according to ethnic origin. In Caucasians a homozygous deletion of the RhD gene is the predominant cause, but in black Africans the RhD gene is intact but non-functional. This is known as the RhD-pseudogene (RhD-Psi).

It contains a 37 base pair insert in exon 4 and a nonsense mutation in exons 5+6, which may introduce stop codons preventing translation.3 For an assay to be accurate across all populations, it must therefore target multiple exons in the RhD gene.

The Cell3 Direct: Fetal RhD genotyping kit targets sequences specific for exons 5, 7 and 10 of the RhD gene and can distinguish between RhD positive, RhD negative and RhD PSI genotypes making it suitable for any population.

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Sensitive qPCR screening for fetal RhD

The technical sensitivity of our assay was demonstrated using RhD positive genomic DNA spiked into an RhD negative background at 10%, and 1% ratios (equivalent to 30 and 3 genomic equivalents) to reproduce realistic fetal fractions.

Amplification of all targets across all replicates was observed even at the lowest 1% spike-in fraction, with RhD exon 5 assay capable of discriminating the RhD PSI variant.

Cell3 Direct: Fetal RhD Genotyping kit sensitivity and specificity test

Figure 1: Assay sensitivity and specificity test with spike-in genomic DNA samples

Direct from plasma vs extracted cffDNA

Our direct-from-plasma protocol was compared with extracted cfDNA and results were demonstrated to be comparable using the same plasma sample (RhD positive, 24 weeks gestation).

Amplification plots of direct-from-plasma testing shows robust amplification of all targets: RhD exon 5 (blue), RhD exons 7 and 10 (green) and CCR5 (black).

qPCR amplification plots comparing direct-from-plasma to extracted cfDNA samples

Figure 1a: Extracted cfDNA amplification.

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Figure 2b: Direct from plasma amplification.


See our customer publications

ProductCatalog No.
Cell3™ Direct: Fetal RhD Genotyping kit, tube format – 96 reaction kitPCR_RHD_GEN_96

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