The best approach for early prediction of fetal gender by using free fetal DNA from maternal plasma

OBJECTIVES: Detection of free fetal DNA (ffDNA) in maternal blood during pregnancy has given rise to the possibility of developing new noninvasive approaches for early prenatal diagnosis.On a large-scale study, two protocols of real-time polymerase chain reaction (PCR) were compared in order to establish which Y-specific locus, either multicopy DYS14 or single copy SRY sequence, was the most suitable for developing a test with high diagnostic efficiency for early fetal gender assessment. The second aim was to assess whether the combination of the two detection systems could increase the performance of the prenatal test. METHODS: We analyzed 145 plasma samples from healthy pregnant women between 11 and 12 weeks of singleton gestation. For each sample, fetal gender was determined by using both protocols (DYS14 and SRY) during the same real-time PCR run. RESULTS: The data obtained by the DYS14 and SRY assays showed an efficiency in fetal gender prediction of 97.9 and 80%, respectively. It is not advisable to combine the two protocols because this association does not help in further improvements in fetal gender prediction. CONCLUSIONS: DYS14 assay is the best approach for early fetal gender assessment because it is more sensitive, accurate, and efficient than the SRY assay.