Y-chromosome identification in circulating cell-free fetal DNA using surface plasmon resonance

Objective: Since the discovery of cell-free fetal DNA (cffDNA) in maternal plasma, diagnostic non-invasive prenatal methods have been developed or 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 such as Duchenne muscular dystrophy, hemophilia and congenital adrenal hyperplasia. Surface plasmon resonance (SPR)-based biosensors might be useful for these studies, because they allow to monitor the molecular interactions in real-time providing qualitative and quantitative information, through kinetics, affinity and concentration analyses. Methods: The BiacoreTM X100 has been applied to identify Y-chromosome sequence in cffDNA obtained from plasma samples of 26 pregnant women at different gestational ages. We have performed SPR-based analysis of SRY PCR products using SRY-specific probes immobilized on the sensor chip. Results: We have demonstrated that there is a statistically significant difference between samples collected by pregnancies carrying male or female fetuses. Moreover, cffDNA obtained at early gestational ages and not detectable by conventional quantitative real-time PCR can be discriminated with high accuracy and reliability using SPR-based biosensors. Conclusions: These data, in addition to their direct applicability in more extensive diagnostic trials, should be considered as the basis of future developments.