Highly Multiplexed Analysis of CRISPR Genome Editing Outcomes in Mammalian Cells

CRISPR-Cas-based genome editing has enabled efficient genetic engineering of a range of organisms and sparked revolutions in many fields of biology. After Streptococcus pyogenes Cas9 was first demonstrated for mammalian genome editing, many CRISPR-associated (Cas) protein variants have been isolated from different species and adopted for genome editing. Furthermore, various effector domains have been fused to these Cas proteins to expand their genome-editing abilities. Although the number of genome-editing tools has been rapidly increasing, the throughput of cell-based characterization of new genome-editing tools remains limited. Here we describe a highly multiplexed genome editing and sequencing library preparation protocol that allows high-resolution analysis of mutation outcomes and frequencies induced by hundreds to thousands of different genome-editing reagents in mammalian cells. We have successful experiences of developing several key genome-editing tools using this protocol. The protocol also is designed to be compatible with robotic liquid handling systems for further scalability.