library_construction_protocol: Genomic DNA from both top and bottom 10% cell fractions separately (around 5M cells in each fraction) using the QIAGEN DNeasy Blood and Tissue kit (Cat No. 69504) according to manufacturer's instructions. SgRNA sequences were amplified from genomic DNA via PCR, followed by a cleanup step using the QIAGEN QIAquick PCR purification kit (Cat-#: 28104) according to the manufacturer's instructions. Sequencing libraries were created using Illumina TruSeq adapters according to the manufacturer's protocols.