CHIP (clonal hematopoiesis of indeterminate potential)
In one sentence
Clonal hematopoiesis of indeterminate potential (CHIP) is a defined category of acquired mutations in blood-forming cells, without a detectable blood cancer.
The intuition
Imagine a tree with one branch that grows unusually large. Its leaves share the branch's history. A blood-forming cell can likewise produce many descendants carrying the same acquired mutation. That family is a clone.
The analogy ends at cause: a larger clone is not automatically cancer, and a mutation's name does not tell us which tissue released it.
How it works
Clonal hematopoiesis (CH) is the broader phenomenon of blood-cell clones carrying acquired genetic changes. CHIP names one defined category within it. The National Cancer Institute's definition requires a mutation in a blood-cancer-associated gene at a variant allele fraction (VAF) of at least 2%, without detectable hematologic cancer. VAF counts variant alleles among evaluated alleles; it is not automatically the percentage of cells.
A smaller blood-cell clone can still contribute a real mutation to plasma. Falling below CHIP's conventional threshold does not make that mutation tumor-derived or a sequencing error.
When cells turn over, they release cell-free DNA (cfDNA). Some plasma variants therefore come from blood cells rather than the solid tumor. Genes can be mutated in both compartments. A familiar cancer-associated gene is insufficient proof of origin.
The DNA change may be real while its attribution to a solid tumor is wrong.
Matched white-blood-cell sequencing provides a useful comparison. Its gene coverage, molecule depth and detection rules matter. A clone below that test's sensitivity may remain unseen. A variant present in both blood and tumor needs careful interpretation; “subtract every blood match” is not a complete attribution method. Razavi and colleagues studied paired plasma, blood-cell and tumor sequencing, including an explicit ambiguous-source category.
CH becomes more common with age, but there is no age at which a plasma variant can simply be dismissed. Some cancer treatments can favor existing clones with particular DNA-damage-response mutations. Bolton and colleagues demonstrated therapy-associated selection; that does not mean every new detection was newly caused by treatment.
Why it matters in cancer
This is a biological source of interference in plasma mutation interpretation. It matters when selecting tracking targets, interpreting resistance variants or assessing a low-level signal. A CHIP finding can also have separate health implications, but it is not itself a leukemia diagnosis or a solid-tumor treatment instruction.
How it is measured
| Assay-card field | What to keep attached |
|---|---|
| Measures and how | Sequence blood-cell DNA, identify acquired variants, estimate VAF and interpret clinical context; compare with plasma and tumor when attributing a liquid-biopsy signal |
| Input and consumption | Blood cells from a blood draw; sequencing consumes extracted DNA. A tumor comparison uses separately obtained material |
| Time | Blood/plasma collection dates and treatment exposure; a later comparator may represent a changed clone |
| Output and units | Gene and variant, VAF as a fraction or percent, coverage and any classification qualifications |
| Thresholds | CHIP's conventional 2% VAF definition differs from the assay's detection limit and from broader CH |
| Controls and failure modes | Matched specimens, identity checks and error controls; limited coverage, shallow sampling, contamination or shared variants can leave source unresolved |
| Cannot tell you | Which lesion is shedding, whether a small clone will progress, or which cancer treatment benefits someone |
| Validation tier | The exact sequencing method and intended use determine research or clinical status; a CH attribution rule is not universal device approval |
Common confusions
- CH versus CHIP: small clones outside the CHIP definition can still affect a plasma assay.
- Blood origin versus sequencing noise: a genuine blood-cell mutation can be irrelevant to the solid tumor.
- Blood match versus perfect filter: absence or presence needs interpretation under both assays' limits.
- Acquired versus tumor-specific: somatic means acquired; it does not mean malignant.
Try it
A fictional plasma assay detects a variant. Sensitive matched blood-cell sequencing finds it at 0.8% VAF. Can the team call it CHIP, or assume it came from the solid tumor?
Answer: neither follows from these facts. The blood result supports a blood-cell contribution, even below the conventional CHIP threshold. Tumor evidence, shared variants and the methods' limits still matter. Keep origin and clinical classification separate.
Explain it back
“Finding a real mutation in plasma does not prove tumor origin because ___.”
One possible answer: blood-cell clones also release DNA, and attribution depends on appropriate comparisons and detection limits.
Takeaway
First establish the source of a plasma variant; then ask what it means.
Related concepts
Tumor-informed monitoring, DNA-pattern measurements, and blood–imaging discordance.
Sources and scope
Source check: October 10, 2026. General biology and source attribution; no clone-specific risk forecast or care recommendation. Expert and learner review remain pending.
- NCI: CHIP definition — formal category and VAF threshold.
- Razavi et al. 2019: sources of plasma cfDNA variants — paired-compartment sequencing in metastatic cancers and non-cancer controls.
- Bolton et al. 2020: therapy and clonal hematopoiesis — exposure-dependent selection of blood-cell clones.