# cfDNA (cell-free DNA, in aging)

Cell-free DNA (cfDNA) is short fragments of DNA floating in your blood plasma. They are released by cells that die, by apoptosis or necrosis. (The fragments are typically 140-200 bp from a single nucleosome, or 300-400 bp from two.) Labs measure it by fluorometry (Qubit), qPCR, or droplet digital PCR, after extracting it from plasma. Healthy adults run about 1-10 ng/mL. cfDNA rises with age, chronic inflammation ('inflammaging'), hard exercise, sepsis, autoimmune disease, trauma, and active cancer. So it is seen as an overall readout of tissue turnover and immune activity. A 2018 study (Moss et al.) showed something powerful: each cell type has its own methylation signature, so you can map which organ the cfDNA came from. That allows non-invasive measurement of cell death in specific organs. cfDNA is the raw material for liquid-biopsy cancer detection, transplant-rejection monitoring, non-invasive prenatal testing, and multi-cancer early detection. The main pitfalls: red-cell breakdown (hemolysis) during the blood draw, and delayed plasma separation.

## Sources

- Moss J, Magenheim J, Neiman D, et al.. (2018). Comprehensive human cell-type methylation atlas reveals origins of circulating cell-free DNA in health and disease. Nature Communications. https://doi.org/10.1038/s41467-018-07466-6
- Duvvuri B, Lood C. (2019). Cell-free DNA as a biomarker in autoimmune rheumatic diseases. Frontiers in Immunology. https://doi.org/10.3389/fimmu.2019.00502
- Teo YV, Capri M, Morsiani C, Pizza G, Faria AMC, Franceschi C, Neretti N. (2019). Circulating cell-free DNA in aging and age-related disease. Aging Cell. https://doi.org/10.1111/acel.12890

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_Canonical: https://longevity-switzerland.com/en/glossary/cfdna-aging · Part of Longevity Cities · Updated 2026-06-22_