Reliability and clinical application of fetal RhD genotyping with two different fluorescent duplex polymerase chain reaction assays: three years' experience.
OBJECTIVE
This study was designed to evaluate accuracy and clinical usefulness of fetal RhD genotyping with fluorescent duplex polymerase chain reaction.


METHODS
Two RhD-specific gene fragments (exon 10 in polymerase chain reaction 1 and exon 7 in polymerase chain reaction 2) were amplified in samples from 213 fetuses.


RESULTS
Amplification failed in 0.9% of the specimens, and equivocal results were found in 1.4% of the specimens. Of the analyses, 6.6% had to be repeated. The concordance of genotyping and serotyping was 99.0% for each polymerase chain reaction. False-positive results were noted in 4 fetuses. Concordant findings from both assays indicated the correct serotype for all fetuses. In 44 alloimmunized pregnancies, further invasive procedures were avoided for 5 of the 6 genotypically RhD-negative fetuses. Only two of 38 RhD-positive fetuses had a hemoglobin level <8 g/dL at first fetal blood sampling.


CONCLUSIONS
Fetal genotyping at distinct regions of the RhD gene is reliable and improves the care management of sensitized women.
Crombach
G
G
Department of Obstetrics and Gynecology, University of Düsseldorf, Germany.
Niederacher
D
D
Larbig
D
D
Picard
F
F
Tutschek
B
B
Beckmann
M W
MW
Bender
H G
HG
D000653:Amniotic Fluid / Q000737:chemistry; D004247:DNA / Q000032:analysis; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D005456:Fluorescent Dyes; D005838:Genotype; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D011247:Pregnancy; D011446:Prospective Studies; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012204:Rh-Hr Blood-Group System / Q000235:genetics*