22T0035429 Normal in  tumor blood analysis group
cfDNA was isolated from the blood samples using commercially available kits QIAamp MinElute cfDNA Midi Kit (Cat. No.: 55284, Qiagen, Germany), following the manufacturer's protocols. Subsequently, 5-10 ng of cfDNA were used to generate RRBS libraries as described previously with modification26. The cfDNA was dephosphorylated using calf intestinal alkaline phosphatase (CIP, Cat. Log., M0525, New England Biolabs, USA). We processed each sample individually without pooling from MspI digestion till PCR enrichment of bisulfite-converted DNA. The indexed RRBS libraries were pooled accordingly and sequenced on a NovaSeq 6000 sequencer (Illumina, USA) with 175-bp paired-end reads