The efficacy of fetal genetic diagnosis using fetal nucleated erythrocytes in maternal blood

Choi, Jin; Choi, Young Min; Shin, Hee Chul

Abstract

OBJECTIVE
The conventional methods to determine fetal genetic status, such as amniocentesis or chorionic villi sampling(CVS) have small procedure-related risk of abortion. Recently, several researchers reported that fetal genetic status, such as sex, can be confirmed by fetal nucleated erythrocytes in maternal blood and this method might reduce such risk. Therefore, in this study, we attempted to determine the basic fetal genetic status, sex, with fetal nucleated erythrocytes. METHODS: In twelve pregnant women who undertook amniocentesis or CVS, 20 ml of venous blood was drawn immediately before the procedure and the nucleated erythrocytes were recovered by magnetic activated cell sorting(MACS). After MACS, DNA was extracted from 200 microliter of sample and single nucleated erythrocyte was obtained by additional procedure, immunostaining, and microdissection. After recovery of nucleated erythrocytes by microdissection, nested polymerase chain reaction(PCR) and fluorescent PCR of amelogenin gene were performed to identify the fetal gender. RESULTS: The DNA of enriched erythrocytes after MACS could identify the fetal gender in the 58.3% of the samples by nested PCR. After the recovery of single nucleated erythrocyte by MACS, immunostaining and microdissection, the minute DNA in a single cell could be amplified by primer extension preamplification(PEP), nested PCR, and fluorescent PCR. Fetal genders were correctly identified in 8 out of 12 (66.7 %). CONCLUSION: Through this study, we could conclude that fetal nucleated erythrocytes in maternal blood might be sufficient sample to determine fetal sex. And single cell isolation by microdissection could get the better results than nested PCR after MACS only. However, in spite of the pregnancy of male fetus, female specific bands were obtained after nested PCR of amelogenin in several cells, which might suggest that part of nucleated erythrocytes in maternal blood might be maternal origin. Therefore, to determine fetal genetic condition by nucleated erythrocytes in maternal blood, further improvements of methods to identify the nucleated erythrocytes of fetal origin are needed.