Cell-free DNA (cfDNA) sequencing is a powerful noninvasive approach for the diagnosis of diseases, genetic defects, and infectious agents. However, numerous clinical samples are either at a low quantity or of poor quality due to various reasons.

To overcome these problems, we have developed T oligo-primed polymerase chain reaction (TOP-PCR) for full-length unbiased amplification of minute DNA samples. Results have shown that TOP-PCR is a superior method over the method used by Illumina for DNA amplification.