Reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women.
OBJECTIVE
The objective of this study was to establish a reliable test for prenatal prediction of fetal RhD type using maternal plasma from RhD negative women. This test is needed for future prenatal Rh prophylaxis.


METHODS
A novel real-time PCR-based assay targeting RHD exon 7 combined with a published assay for RHD exon 10 were used to determine the fetal RHD status in DNA extracted from plasma, sampled from 56 pregnant RhD negative women in 15th-36th week of gestation. Thirty-eight samples were from ongoing pregnancies of Danish women and 21 samples from 18 pregnant women were stored anonymized samples from the International Blood Group Reference Laboratory, Bristol, United Kingdom. Prediction of fetal RhD type was compared with the serological result obtained after birth.


RESULTS
The prediction of the fetal RhD type was in 100% concordance with the serological RhD type from the 16th week of gestation. One sample from the 15th week of gestation was inconclusive. The number of copies of fetal RHD DNA was found to increase with gestational age. Low levels of DNA were found to follow the Poisson distribution (p = 1.0000).


CONCLUSIONS
Our set-up was very reliable for determination of fetal RhD genotype, and thus will be of value in prenatal Rh prophylaxis and in the management of immunized women.
Clausen
Frederik Banch
FB
H : S Blodbank KI2034, Copenhagen University Hospital, Copenhagen, Denmark. frederik.banch.clausen@rh.hosp.dk
Krog
Grethe Risum
GR
Rieneck
Klaus
K
Nielsen
Leif Kofoed
LK
Lundquist
Rasmus
R
Finning
Kirstin
K
Dickmeiss
Ebbe
E
Hedegaard
Morten
M
Dziegiel
Morten Hanefeld
MH
D004247:DNA / Q000097:blood*; D015342:DNA Probes; D005091:Exons; D005260:Female; D005315:Fetal Diseases / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D005838:Genotype; D005865:Gestational Age; D006801:Humans; D016133:Polymerase Chain Reaction; D011237:Predictive Value of Tests; D011247:Pregnancy / Q000097:blood; D011296:Prenatal Diagnosis / Q000379:methods*; D015203:Reproducibility of Results; D012204:Rh-Hr Blood-Group System / Q000235:genetics*; D012680:Sensitivity and Specificity
D015342:DNA Probes; D012204:Rh-Hr Blood-Group System; D004247:DNA