CRISPR Diagnostics\nfor Quantification and Rapid Diagnosis\nof Myotonic Dystrophy Type 1 Repeat Expansion Disorders

Repeat expansion disorders, exemplified by myotonic dystrophy\ntype\n1 (DM1), present challenges in diagnostic quantification because of\nthe variability and complexity of repeat lengths. Traditional diagnostic\nmethods, including PCR and Southern blotting, exhibit limitations\nin sensitivity and specificity, necessitating the development of innovative\napproaches for precise and rapid diagnosis. Here, we introduce a CRISPR-based\ndiagnostic method, REPLICA (<u>re</u>peat-<u>p</u>rimed <u>l</u>ocating of <u>i</u>nherited disease by <u>Ca</u>s3), for\nthe quantification and rapid diagnosis of DM1. This method, using\nin vitro-assembled CRISPR-Cas3, demonstrates superior sensitivity\nand specificity in quantifying CTG repeat expansion lengths, correlated\nwith disease severity. We also validate the robustness and accuracy\nof CRISPR diagnostics in quantitatively diagnosing DM1 using patient\ngenomes. Furthermore, we optimize a REPLICA-based assay for point-of-care-testing\nusing lateral flow test strips, facilitating rapid screening and detection.\nIn summary, REPLICA-based CRISPR diagnostics offer precise and rapid\ndetection of repeat expansion disorders, promising personalized treatment\nstrategies.