BEAMing up for detection and quantification of rare sequence variants

BEAMing allows the one-to-one conversion of a population of DNA fragments into a population of beads. We used rotting circle amplification to increase the number of copies bound to such beads by more than 100-fold. This allowed enumeration of mutant and wild-type sequences even when they were present at ratios less than 1:10,000 and was sensitive enough to directly quantify the error rate of DNA polymerases used for PCR.