4.3 years ago by
Washington University in St. Louis, MO
The short answer is that in most tumor types, most tumors display some amount of subclonal heterogeneity. It's everywhere, and low-frequency events are not being well captured in our standard 50-100x tumor assays.
Update: I can tell you from personal experience that when looking at close to 1000 exomes from TCGA, most (60%+) have detectable subclonal mutations, and I'd wager that most of the rest just didn't have sufficient coverage to uncover additional low-VAF populations. Very few tumors are actually monoclonal.