title: GSM4475563: HAP1 cells,  WT 69 T18 B; Homo sapiens; OTHER
library_construction_protocol: Genomic DNA was extracted using the Wizard Genomic DNA Purification Kit (Promega). Sequencing libraries were prepared in two PCR steps, the first to enrich guide-RNA regions from the genome, and the second to amplify guide-RNA and attach Illumina TruSeq adapters with i5 and i7 indices.