Routine fetal RHD genotyping with maternal plasma: a four-year experience in Belgium

Transfusion. 2008 Feb;48(2):373-81. doi: 10.1111/j.1537-2995.2007.01533.x. Epub 2007 Nov 26.


Background: The objective was to evaluate the diagnostic value of RHD fetal genotyping from the plasma of D- mothers as soon as 10 weeks' gestation in a routine clinical practice in Belgium.

Study design and methods: A prospective study was conducted between November 2002 and December 2006. DNA extraction was performed in an automated closed tube system. Fetal RHD/SRY genotypes were detected in the plasma of 563 pregnant mothers by real-time polymerase chain reaction (PCR) targeting multiple exons 4, 5, and 10 of the RHD gene and targeting an SRY gene sequence. These were compared to the D phenotypes determined in the 581 babies they delivered.

Results: By combining amplification of three exons, the concordance rate of fetal RHD genotypes in maternal plasma and newborn D phenotypes at delivery was 100 percent (99.8% including one unusual false-positive). The presence of nonfunctional RHD genes and the absence of a universal fetal marker, irrespective of fetal sex, did not influence the accuracy of fetal RhD status prediction. The RHD genotyping from 18 twin pregnancies was also assessed. Five weak D women were excluded from the RHD fetal genotyping prediction. Three discrepant results (0.5%) between predicted fetal genotype and cord blood phenotype were not confirmed by the baby phenotypes from venipuncture blood.

Conclusion: Prenatal prediction of fetal RHD by targeting multiple exons from the maternal plasma with real-time PCR is highly sensitive and accurate. Over 4 years, this experience has highly modified our management of D- pregnant women.

MeSH terms

  • Algorithms
  • Belgium
  • DNA / genetics
  • Exons / genetics
  • Female
  • Genotype
  • Humans
  • Infant, Newborn
  • Male
  • Mothers*
  • Phenotype
  • Plasma / metabolism*
  • Pregnancy
  • Rh-Hr Blood-Group System / blood*
  • Rh-Hr Blood-Group System / genetics*
  • Time Factors


  • Rh-Hr Blood-Group System
  • DNA