Clonal hematopoiesis of indeterminate potential, or CHIP, is a condition where a blood-forming stem cell in your bone marrow acquires a genetic mutation and begins producing a growing clan of identical copies of itself. These mutant cells make up a measurable fraction of your blood, yet your blood counts remain normal and you have no symptoms. CHIP is not cancer, but it increases the risk of both blood cancers and heart disease over time.
How CHIP Develops
Every day, your bone marrow churns out billions of new blood cells from a pool of stem cells. Over a lifetime, those stem cells accumulate random mutations each time they divide. Most mutations are harmless passengers. Occasionally, though, a stem cell picks up a mutation in a gene that gives it a slight survival or growth advantage over its neighbors. That cell divides a little faster, or its offspring resist dying off at the normal rate, and gradually its descendants come to represent a detectable share of all blood cells. That expanding family of genetically identical cells is a “clone,” and the whole process is clonal hematopoiesis.
The word “indeterminate” in the name reflects the uncertainty: the clone is there, it carries a mutation associated with blood cancers, but it isn’t causing any disease yet. It may never cause disease. The formal diagnostic threshold requires the mutant clone to represent at least 2% of the DNA copies at that gene location (a measure called variant allele frequency). Below that cutoff, the clone is harder to detect reliably with standard sequencing and carries less established risk.
The Genes Involved
Three genes account for the majority of CHIP mutations: DNMT3A, TET2, and ASXL1, sometimes referred to collectively as “DTA” genes. All three are epigenetic regulators, meaning they control how other genes are switched on or off without changing the underlying DNA sequence. When one of these regulators is disrupted, the stem cell’s normal programming shifts in ways that favor self-renewal.
These mutations are considered early events in the pathway toward blood cancers like myelodysplastic syndromes and acute myeloid leukemia, but on their own they are typically not enough to trigger full-blown disease. Additional mutations, accumulated over years or decades, are usually required for a malignancy to develop. That’s why CHIP is best understood as a risk factor rather than a diagnosis of cancer.
Who Gets CHIP
CHIP is overwhelmingly age-related. Prevalence is very low in young adults, roughly 5% by age 60, then climbs steeply to around 30% in people over 80. Because it tracks so closely with aging, some researchers use the term “age-related clonal hematopoiesis” interchangeably with CHIP. A small percentage of younger people carry these clones too, and studies in stroke patients under 60 have found detectable CHIP in a meaningful minority, with prevalence roughly four times higher in 50- to 60-year-olds than in those under 40.
The condition is typically discovered incidentally, often when someone undergoes genetic sequencing for another reason, such as tumor profiling for a solid cancer or a research study. Most people with CHIP have no idea they carry it.
Risk of Blood Cancer
The relative risk of developing a myeloid malignancy like myelodysplastic syndrome or acute myeloid leukemia is elevated in people with CHIP, but the absolute risk remains low: roughly 0.5% to 1% per year. That means in any given year, 99 out of 100 people with CHIP will not develop a blood cancer. Over a decade, though, the cumulative probability becomes more meaningful, especially for people with larger clones, multiple mutations, or higher-risk gene profiles.
Certain features push the risk higher. A larger clone size (higher variant allele frequency), mutations in more than one driver gene, or mutations in genes outside the DTA trio all signal a greater chance of progression. When a person with CHIP also develops low blood counts (cytopenias), the diagnosis shifts to a related condition called CCUS, or clonal cytopenia of undetermined significance, which carries a substantially higher risk of progressing to a frank malignancy.
The Cardiovascular Connection
One of the most important discoveries about CHIP is that it significantly raises cardiovascular risk. People with CHIP face a higher rate of atherosclerosis, heart attacks, heart failure, and stroke. The mechanism centers on inflammation. Mutant blood cells, particularly those with TET2 mutations, produce higher levels of inflammatory signaling molecules. In animal studies, mice transplanted with TET2-deficient bone marrow developed larger atherosclerotic plaques, driven by activation of an immune alarm system called the NLRP3 inflammasome, which ramps up production of inflammatory proteins including IL-1β and IL-6.
Human evidence supports this link. In the CANTOS trial, which tested an anti-inflammatory drug that neutralizes IL-1β, patients who happened to carry TET2 CHIP mutations experienced a larger reduction in major cardiovascular events when treated with the drug compared to those without the mutation. This suggests the inflammatory pathway driven by CHIP is not just a laboratory finding but a treatable contributor to heart disease.
A meta-analysis of multiple studies found that CHIP is associated with a 34% increase in the risk of dying from any cause (a hazard ratio of 1.34), with cardiovascular disease accounting for a large share of that excess mortality.
How CHIP Is Detected
CHIP is identified through DNA sequencing of a blood sample, most commonly using next-generation sequencing with targeted gene panels that cover the known driver mutations. Standard sequencing at typical clinical depths can reliably detect clones at the 2% threshold. Newer, higher-sensitivity techniques that use deeper sequencing (thousands of reads per position instead of hundreds) can pick up much smaller clones, sometimes below 1%, but detecting very small clones raises questions about clinical significance since nearly everyone accumulates tiny clones with age.
There is no routine screening recommendation for CHIP in the general population. Detection usually happens as a secondary finding during genetic testing ordered for other reasons. Some academic medical centers have begun establishing dedicated CHIP clinics to help patients interpret their results and manage risk.
How CHIP Differs From Related Conditions
CHIP sits within a spectrum of pre-cancerous bone marrow states, and the distinctions matter because they carry different levels of risk.
- CHIP: A cancer-associated mutation is present at 2% or above, but blood counts are normal and there are no signs of disease.
- CCUS (clonal cytopenia of undetermined significance): The same type of mutation is present, but blood counts are abnormally low. This carries a higher risk of progressing to a blood cancer.
- ICUS (idiopathic cytopenia of undetermined significance): Blood counts are low, but no known driver mutation has been found.
The key dividing lines are whether a known mutation is present and whether blood counts are normal. CHIP, by definition, involves a mutation but normal counts. Once counts drop, the clinical picture changes and closer monitoring becomes necessary.
Monitoring and Management
There is no treatment for CHIP itself, since it is not a disease but a risk state. Management focuses on surveillance and reducing the downstream risks it creates. Most people with CHIP are monitored with periodic blood counts to watch for any decline that might signal progression toward a blood cancer. The frequency of monitoring depends on the size of the clone and which genes are mutated.
Because of the strong cardiovascular link, many CHIP clinics also refer patients for cardiovascular risk assessment. This typically means optimizing the standard modifiable risk factors: blood pressure, cholesterol, blood sugar, smoking cessation, and exercise. For someone already at elevated cardiac risk, knowing they also carry CHIP may shift how aggressively those risk factors are managed. Patients at higher risk for leukemia based on their mutation profile or clone size may undergo additional testing, including bone marrow biopsy, to rule out early signs of a developing malignancy.