The utility of an erythroblast scoring system and gender-independent short tandem repeat (STR) analysis for the detection of aneuploid fetal cells in maternal blood / 대한산부인과학회지

ABSTRACT

OBJECTIVE: The aim of this study was to determine whether fetal nucleated red blood cells (NRBCs) could be distinguished from maternal cells in peripheral blood using an erythroblast scoring system. Presumptive fetal NRBCs were further analyzed through the use of fluorescent PCR amplification with polymorphic STR markers to prove fetal origin. METHODS: NRBCs were isolated by density gradient separation, CD15/45 depletion, and gamma hemoglobin positive selection from peripheral blood of seven women who had undergone termination of pregnancy because of fetal trisomy 21 (n=4), 18 (n=1), and 13 (n=2). Candidate fetal NRBCs, based on four discrete morphological and hemoglobin staining criteria, were then subjected to fluorescent PCR amplification of chromosome 21 short tandem repeat (STR) markers (D21S1411, D21S11) and chromosome 18 STR markers (D18S535). RESULTS: In all cases candidate fetal NRBCs were accurately identified based on erythroblast scoring system and confirmed to be fetal in origin based on the presence of shared and non-shared polymorphic DNA alleles when compared to DNA isolated from maternal cells. Also in five cases aneuploid fetal cells in maternal blood were identified through the use of fluorescent PCR amplification with polymorphic STR markers. CONCLUSION: We were able to distinguish fetal NRBCs from maternal cells and prove fetal origin independent of gender. These results suggest that this novel combined approach to fetal cell isolation through using an erythroblast scoring system and genetic analysis by STR analysis is a promising method for noninvasive prenatal diagnostic applications.