SPR-based non-invasive prenatal testing for fetal sex determination

Since the discovery of cell-free fetal DNA (cffDNA) in maternal plasma, diagnostic non-invasive prenatal methods have been developed and optimized for fetal sex determination and identification of genetic diseases. As far as fetal sex determination, this might be important for therapeutic intervention on sex-associated pathologies. Biosensors based on surface plasmon resonance (SPR), such as BiacoreTM X100, might be available for these studies. In fact, SPR biosensors permit to monitor the interactions between biomolecules in real-time, providing both qualitative and quantitative information, through kinetics, affinity and concentration analyses. In this study BiacoreTM X100 has been applied to identify the Y-chromosome in cffDNA obtained from plasma samples of 27 pregnant women at different gestational ages. We have performed SPR-based analysis of SRY-PCR products using a BiacoreTM instrument and an SRY-specific probe immobilized on the sensor chip. The results suggest that there is a statistically significant difference between samples collected by pregnancies carrying male or female fetuses. Moreover cffDNA, obtained at early gestational ages (6th-7th week) and not detectable by conventional quantitative real-time PCR, might be discriminated with high accuracy and reliability using SPR-based biosensors.