Noninvasive fetal RHD genotyping by maternal plasma with capillary electrophoresis.

Background: Recently, a more accurate and reliable screening test has been investigated for noninvasive prenatal fetal RHD genotyping from D- women. The objective of this study was to perform the new method of noninvasive fetal RHD genotyping with maternal plasma from D- women by use of capillary electrophoresis.

Study Design And Methods: Blood samples were obtained from 8 D+ and 8 D- nonpregnant donors and mixed to make test plasma samples. DNA was extracted and the appropriate conditions relating to the initial sample volume as well as polymerase chain reaction cycle numbers were analyzed to detect the RHD gene with RHD exon 10 primer. Blood samples were also obtained from 13 D- pregnant women ranging from the 12th to 39th weeks of gestation. The presence of the RHD gene and Y-chromosome-specific STR (Y-STR) derived from the fetus was analyzed. The results were compared with the D status of newborns.

Results: In samples from 12 D- pregnant women, the RHD gene was detected. In one sample, the RHD gene was not detected but Y-STR loci were demonstrated in this sample, indicating a D- male baby. The results of fetal genotyping were all in concordance with the postpartum samples by serologic tests on D as well as with the sex of newborns.

Conclusion: Capillary electrophoresis can be used for the determination of fetal RHD status in D- women. This diagnostic method is useful for the noninvasive prenatal diagnosis of the fetal RHD genotyping from D- women.