gww and patall both point out that this is related to cfDNA [1]: > Circulating free DNA (cfDNA) are degraded DNA fragments released to the blood plasma. [1] h

gww and patall both point out that this is related to cfDNA [1]: > Circulating free DNA (cfDNA) are degraded DNA fragments released to the blood plasma. [1] https://en.wikipedia.org/wiki/Circulating_free_DNA https://en.wikipedia.org/wiki/Circulating_free_DNA