The invention discloses a construction method and detection method of a trace fragmented
DNA methylation detection
library. The
library construction method of the present invention comprises: linkingfragmented
DNA to a
methylation linker, wherein all cytosines on the
methylation linker are methylated cytosines, the methylation
linker includes a
long chain and a short chain which are complementaryto form a
double chain, and the
long chain includes a sequencing platform universal sequence, a single molecule tag sequence, a sample tag sequence and a sequencing primer binding sequence; and the
DNA linked with the methylation linker is treated with
sodium bisulphate, so that the
cytosine C in a non-methylated CpG island is converted into
uracil U; and a specific primer and a universal primerare used for PCR amplification enrichment of a target region subjected to
sodium bisulfite treatment and containing a
CpG site to be detected, so that a
library available for on-
machine sequencing isobtained. According to the invention, methylation of trace DNA taken through
liquid biopsy can be detected, and the
CpG island methylation status of multiple regulatory regions of
multiple tumor suppressor genes can be quantitatively detected simultaneously.