DNA damage induced by ionizing radiation from electron capture decay of iodine-125

Iodine-125 (^125I) is a radioisotope that decays primarily via electron capture, producing low-energy Auger electrons. When ^125I is incorporated near or within DNA (for instance, as a DNA-incorporated radiopharmaceutical), these electrons cause highly localized DNA ionizations, leading mainly to clustered DNA double-strand breaks (DSBs) and other complex DNA lesions. Such damage is highly cytotoxic and poorly repaired, underpinning the use of ^125I in targeted cancer therapy and molecular radiotherapy, but also carrying risks for normal tissues. The damage pattern is distinct from more diffuse, lower-density energy depositions produced by β- or γ-radiation: Auger electrons cause extremely localized, high-density DNA breaks that can overwhelm cellular repair mechanisms, resulting in cell death or irreversible genomic damage. This entry is best described as a "mechanism of action" or "biological effect" rather than a canonical molecular target. It is pivotal for the action of certain radiopharmaceuticals but is not itself a protein, receptor, or gene product.

Other names

DNA double-strand breaks via Auger electron emission from iodine-125 decayAuger electron-induced DNA damageDNA damage by ^125I decay

Emission of low-energy Auger electrons from iodine-125 decay causes dense, localized ionizations in DNA, resulting in clustered DNA damage (predominantly double-strand breaks) through direct and indirect effects.