Prevalence of RhD status and clinical application of non-invasive prenatal determination of fetal RHD in maternal plasma: a 5 year experience in Cyprus.

Background: After the discovery that cell-free fetal DNA (cffDNA) is circulating in the maternal plasma of pregnant women, non-invasive prenatal diagnosis for fetal RhD in maternal plasma in RhD negative women at risk for haemolytic disease of the newborn (HDN) was clinically established and used by many laboratories. The objectives of this study are: (a) to assess the feasibility and report our experiences of the routine implementation of fetal RHD genotyping by analysis of cffDNA extracted from maternal plasma of RhD negative women at risk of HDN, and (b) to estimate the RhD phenotype frequencies, the RHD genotype frequencies and the RhD zygosity in the Cypriot population.

Methods: cffDNA was extracted from maternal plasma of 73 RhD negative pregnant women.

Noninvasive fetal blood grouping: present and future.

Identification of the molecular basis of the D polymorphism of the Rh blood group system in the 1990s made it possible to predict D phenotype from DNA. The most valuable application of this has been the determination of fetal D type in pregnant D-negative women with anti-D. Knowledge of fetal D type reveals whether the fetus is at risk of hemolytic disease of the fetus and newborn so that the pregnancy can be managed appropriately.

Noninvasive prenatal diagnosis of fetal blood group phenotypes: current practice and future prospects.

Fetuses of women with alloantibodies to RhD (D) are at risk from hemolytic disease of the fetus and newborn, but only if the fetal red cells are D-positive. In such pregnancies, it is beneficial to determine fetal D type, as this will affect the management of the pregnancy. It is possible to predict, with a high level of accuracy, fetal blood group phenotypes from genotyping tests on fetal DNA.

The use of maternal plasma for prenatal RhD blood group genotyping.

Alloimmunization to the blood group antibody anti-RhD (anti-D) is the most common cause of hemolytic disease of the fetus and newborn. Knowledge of fetal D type in women with anti-D makes management of the pregnancy much easier and avoids unnecessary procedures in those women with a D-negative fetus. Fetal D typing can be performed by detection of an RHD gene in cell-free DNA in the plasma of D-negative pregnant women.

Effect of high throughput RHD typing of fetal DNA in maternal plasma on use of anti-RhD immunoglobulin in RhD negative pregnant women: prospective feasibility study.

Objectives: To assess the feasibility of applying a high throughput method, with an automated robotic technique, for predicting fetal RhD phenotype from fetal DNA in the plasma of RhD negative pregnant women to avoid unnecessary treatment with anti-RhD immunoglobulin.

Design: Prospective comparison of fetal RHD genotype determined from fetal DNA in maternal plasma with the serologically determined fetal RhD phenotype from cord blood.

Setting: Antenatal clinics and antenatal testing laboratories in the Midlands and north of England and an international blood group reference laboratory.

Fetal blood group genotyping: present and future.

Prediction of fetal blood group from DNA is usually performed when the mother has antibodies to RhD, to assess whether the fetus is at risk from hemolytic disease of the fetus and newborn (HDFN). Over the last five years RhD testing on fetal DNA in maternal plasma has been introduced. At the International Blood Group Reference Laboratory (IBGRL) we employ real-time quantitative polymerase chain reaction (RQ-PCR) to detect RHD exons 4, 5, and 10, which also reveals RHDpsi.

Use of maternal plasma for noninvasive determination of fetal RhD status.

Determination of the fetal RhD typing using free fetal DNA in maternal plasma is beginning to enjoy widespread acceptance in Europe. Case 1, the partner of an RhD-sensitized patient, was identified with a heterozygous paternal phenotype by serologic testing. Maternal plasma was drawn at 18 weeks' gestation to determine the fetal RhD status.