Scientists have identified an inheritable genetic variant through a genome-wide association study (GWAS) that protects against clonal haematopoiesis and its progression to leukaemia.Clonal haematopoiesis arises in the blood through the accumulation of somatic mutations in stem and progenitor cells that gain a competitive advantage and lead to clonal expansion.[This process increases the risk of leukemia, as well as cardiovascular and inflammatory diseases.2 A genetic variant prevents or slows this process, conferring genetic resistance to leukemia.2 The study by Agarwal et al. on page 52 of this issue of Science reported a major finding about this protective variant.Advances in DNA sequencing have enabled early detection of somatic mutations in healthy tissues.2 The study by Agarwal et al.