Protocol for analyzing plasma cell-free DNA fragment end motifs from ultra-low-pass whole-genome sequencing

Circulating cell-free DNA (cfDNA) fragment end motif profiles are a promising biomarker in precision oncology. Here, we present a protocol for analyzing plasma cfDNA fragment end motifs from ultra-low-pass whole-genome sequencing (WGS) data. We detail a pipeline composed of sequential bash scripts for processing post-alignment BAM files. Subsequently, we outline the procedure for downstream analysis and visualization of 4-mer as well as other n-mer cfDNA end motifs in R. For complete details on the use and execution of this protocol, please refer to Liu et al.(1).