We know that in next-generation sequencing (NGS), the unique molecular identifier (UMI) can reduce or eliminate sequencing or PCR errors and result in very high accurate data. Therefore, UMI is widely used in rare mutation detection. A typical application is cancer early detection or minimal residual disease (MRD) detection that try to find the very rare DNA from cancer cells in the blood.
However, we also know that the cell-free DNA in the blood is very low, typically 5 ng in 1 mL blood. And it usually takes about 10 mL blood to get about 50 ng DNA to get sequenced with UMI. Limited DNA input leads to many false negatives.
So I came up with an idea: What if I got a sample with plenty of DNA? Can I detect rare mutations using UMI in this sample?
The UMI library preparation protocols I have met all use a small amount of DNA input, say 50ng. If I have 1μg DNA, do I have to cut it to 50ng to prepare the UMI library?