Table 1 The dd-cfDNA assay and its application in liver transplantation

qPCR

Low cost and easy to operate;

Suitable for mass screening

Low sensitivity and specificity;

Inability to detect low concentrations of dd-cfDNA

One of the most used tests

[19, 21, 37]

dd-PCR

High sensitivity;

Capable of precisely detecting minor variations in dd-cfDNA

The procedure is complex and expensive; Unsuitable for widespread application; Requires high-quality samples

Suitable for precise monitoring of dd-cfDNA;

Holds considerable predictive value in the early stages of acute rejection

[38, 39]

NGS

Extremely sensitive;

Capable of detecting mutations, methylation, and other alterations in dd-cfDNA

High cost; Complex data processing

Capable of providing a comprehensive analysis of mutations and genomic alterations

[29, 36, 40]

Genome analysis

Epigenetic changes in cfDNA can be detected

The methodology is complex;

Data analysis requiring advanced technical support

Genomic methylation analysis can provide important information about immune response and rejection

[41,42,43]