These cross-sectional analyses strongly suggest that most of the mosaic anomalies detectable by SNP microarrays appear late in life, because they arise more frequently and/or because they are more readily detected due to clonal expansion. This suggestion is supported by longitudinal observation in one GENEVA subject (the only subject sampled twice who had mosaicism in at least one sample). This subject was sampled at age 66 and again at age 72 (both with DNA from saliva). No mosaic anomalies were detected in the earlier sample, but the later sample contained 5 mosaic deletions, each on a different chromosome. Additional studies with subjects sampled at multiple ages are needed to evaluate the temporal origin and stability of mosaic anomalies.
