We regressed the presence of detectable clonal mosaicism in 26,136 cancer-free individuals on age at DNA collection (in 5 year intervals), sex (male versus female), DNA source (buccal cells versus blood), smoking (ever versus never) and admixture coefficients for African and East Asian ancestry in a logistic model to determine the additional factors that influenced frequency of detectable clonal mosaicism. The source of DNA was known for 87% of individuals, of whom 19% were derived from buccal cells and the remainder from blood. DNA source was not significantly associated with mosaicism (OR=0.83, 0.55-1.26 95% confidence interval (CI), p=0.39). By admixture analysis, 75% of subjects were determined to be of European ancestry, 9% of African ancestry and 16% of East Asian ancestry. Although power was limited, we observed that cancer-free individuals with African admixture were at a lower risk of being mosaic (OR=0.43, 0.20-0.92 95% CI, p=0.03), but not in those with East Asian admixture (OR=0.60, 0.32-1.15 95% CI, p=0.12). We did not observe an association between smoking (ever/never) and frequency of mosaic abnormalities (OR=1.04, 0.75-1.44 95% CI, p=0.81).
