Development of a rapid and sensitive RPA-CRISPR/Cas12a assay for non-invasive pre-implantation genetic testing

Pre-implantation genetic testing (PGT) is served as the primary technology for diagnosing genetic disorders. However, invasive operation may affect embryonic development, which indicates non-invasive methods might have important clinical value. Free DNA in blastocoele fluid provides the possibility for non-invasive diagnosis. The combination of RPA and CRISPR/Cas12a technology is expected to achieve analysis of free DNA in blastocoele fluid and develop an instant diagnostic platform for non-invasive PGT.

In this study, we collected 65 samples of day 6/7 blastocysts formed through intracytoplasmic sperm injection, and blastocysts hatched from the zona pellucida, with the corresponding blastocoele fluid, from the Center of Reproductive Medicine at the Second Affiliated Hospital of Zhengzhou University. The TSPY1 and TBC1D3 genes were analyzed using the RPA-CRISPR/Cas12a system to investigate the diagnostic potential of free DNA in the blastocoele fluid. A single-tube dual-gene assay for blastocoele fluid was successfully constructed using the RPA-CRISPR/Cas12a technology achieving specific detection of the Y chromosome and fluorescence visualization. Interpretatable results could be completed within 1h. By detecting the TSPY1 and TBC1D3 genes in 65 pairs of blastocysts, the accuracy of the Y chromosome in the interpretable results reached 95.4 %.

Free DNA in the blastocoele fluid could serve as a genetic information source for non-invasive PGT. We first established a single-tube dual-gene RPA-CRISPR/Cas12a assay to detect free DNA in blastocoele fluid and achieved rapid amplification and detection with the advantages of easy operation and fluorescence visualization, providing a rapid detection platform for the diagnosis of sex-linked disorders.