Extended Data Fig. 5: cfChIP-seq is highly sensitive.
From: ChIP-seq of plasma cell-free nucleosomes identifies gene expression programs of the cells of origin
a, Schematics of the parameters involved in determining cfChIP-seq sensitivity. 1. Number of informative nucleosomes is the total number of signature-specific nucleosomes in the plasma that carry a mark of interest; 2. The percent contribution of the signature-positive cells to the circulation; 3. Total number of genomes in circulation; 4. The specific capture probability of marked nucleosomes by the cfChIP-seq assay; and 5. The non-specific capture probability of nucleosomes (background). The signal to noise ratio (SNR) is the ratio of the specific to non-specific capture probabilities. b, Simulation analysis of event detection power as a function of percent positive (x-axis) and number of informative locations (y-axis). Detection is defined as 95% probability of assay results (capture & sequencing) that reject the null hypothesis of background signal with p < 0.05 (Poisson test, Methods). Simulation assumes number of genomes = 10,000 (10 ml plasma of healthy donor), capture probability of 1%, and SNR of 500 (Methods, Supplementary Note). The size of several example signatures are shown.
