The strongest predictor of mosaic autosomal abnormalities was age at DNA collection. We examined the effect of aging on the frequency of mosaicism across all studies, which were predominantly individuals over the age of 50. The frequency of cancer-free individuals with detectable clonal mosaic events increased with age, from 0.23% for those under 50 to 1.91% (p=4.8×10−8) for those between the ages of 75 and 79, and with slightly higher frequencies for individuals with cancer (Figure 3). In the early onset cancers (under age 40), which constituted less than 5% of analyzed cases (e.g., testicular cancer and osteogenic sarcoma), we did not observe an increase in mosaic abnormalities. Further studies are needed to investigate the relationship between mosaic abnormalities and cancer in children and young adults, particularly because of the strong association between mosaicism and many developmental disorders. There was no apparent relationship between age at DNA collection and the number, size of mosaic events, or the proportion of abnormal cells (Supplementary Figures 1 and 2).
