Fig. 4

Frequency of fragment endpoints of cfDNA of various lengths around the TSS regions. The 5′ and 3′ boundary of each sequencing reads of different lengths (101–130 bp, 131–140 bp, 141–150 bp,151–160 bp, and 163–169 bp) were separately tallied in consecutive non-overlapping 5 bp windows within − 300 to 500 bp of the TSS, and normalized to the mean sequencing depth of the region. a and b Normalized 5′ fragmentation frequency in a four 166 bp dominant cancer patient cfDNA samples (SRX1921676, SRX1921677, SRX1921678, and SRX1921680) and b one 134/144 bp dominant cancer patient cfDNA sample (SRX1921679). (C and D) Normalized 3′ fragmentation frequency in c four 166 bp dominant cancer patient cfDNA samples (SRX1921676, SRX1921677, SRX1921678, and SRX1921680) and d one 134/144 bp dominant cancer patient cfDNA sample (SRX1921679). In each graph, vertical dashed lines marked the positions of the first peak of the curves downstream of TSS as fitted using locally weighted scatterplot smoothing (LOWESS). e A schematic diagram showing that the shortening of cfDNA molecules occur from both 5′ and 3′ ends