a, NGG sgRNA representation in plasmid pool and cells at conclusion of experiment (left), and in εy:mCherry-high and εy:mCherry-low pools (right), with dotted lines at x = y and x = 8y. b, Quantile–quantile plots of NGG sgRNA εy enrichment scores. c, Cellular dropout scores of NGG sgRNAs relative to genomic cleavage position and repetitive elements. Non-targeting sgRNAs are pseudo-mapped with 5 bp spacing. d, Correlation between cellular dropout and εy enrichment scores.