Our papers exploring mosaic chromosomal alterations in UK Biobank (N~500K; Loh et al. 2020 Nature) and BioBank Japan (N~200K; Terao et al. 2020 Nature) are now online at Nature. Highlights of these studies include discovery of several new risk loci at which acquired mutations systematically duplicate inherited rare coding variants, a polygenic effect in which clonal selection acts on mutant cells that have increased polygenic drive for blood-cell proliferation traits (by replacing one chromosome arm with its homologous counterpart), and population differences in genomic locations of hematopoietic clones mirroring epidemiological differences in rates of B- and T-cell cancers. [Broad news story]