Table 1 Definitions of CHIP, CCUS, ICUS, and IDUS
Condition | Cytopenia* | Dysplasia | Risk of progression | Mutations | Blast (%) |
|---|---|---|---|---|---|
CHIP | No peripheral cytopenia | No or mild (< 10%) | Low to moderate risk of MDS/AML progression | One or more with a VAF of 2–30% DNMT3A, TET2, ASXL1 |  < 5 |
CCUS | Peripheral cytopenia | No or mild (< 10%) | Significant risk of progression to myeloid malignancy | One or more with a VAF of 2–30% SF3B1, SRSF2, U2AF1, ASXL1 |  < 5 |
ICUS | Mild peripheral cytopenia | No or mild (< 10%) | Low risk for hematologic malignancy | Typically, absent or low-frequency mutations |  < 5 |
IDUS | No peripheral cytopenia |  ≥ 10% dysplasia in neutrophils, erythrocytes, and/or megakaryocytes | Uncertain risk of progression | Variable; can include TET2, DNMT3A |  < 5 |