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. Author manuscript; available in PMC: 2012 Mar 1.

Published in final edited form as: Clin Cancer Res. 2011 Jan 19;17(5):1169–1180. doi: 10.1158/1078-0432.CCR-10-2277

Representative electropherograms of the sensitivity study for EGFR T790M. A. Sequencing after standard PCR of undiluted mutant DNA (100%) shows both a mutant peak (T) and a WT peak (C) at position 2369 (arrow) at roughly the same proportions. Serial dilutions of mutant DNA with normal control DNA show a sequential decrease in size of the mutant peak. The mutation is clearly seen at dilutions of 12.5% or higher in both the forward and reverse directions. Below this level, the mutant peak is at the level of the background or completely absent. % M denotes percent of mutant DNA; () denotes SNP at position 2361. B. LNA-PCR/sequencing. With the introduction of the LNA probe, only the mutant peak (T) is seen at position 2369 (arrow) at all dilutions of 0.8% and above. At progressively lower concentrations, the WT peak becomes visible but the mutant peak remains predominant down to 0.1% (percentages have been rounded). At the SNP position () only G is seen with complete suppression of the WT allele.

Inline graphic — Representative electropherograms of the sensitivity study for EGFR T790M. A. Sequencing after standard PCR of undiluted mutant DNA (100%) shows both a mutant peak (T) and a WT peak (C) at position 2369 (arrow) at roughly the same proportions. Serial dilutions of mutant DNA with normal control DNA show a sequential decrease in size of the mutant peak. The mutation is clearly seen at dilutions of 12.5% or higher in both the forward and reverse directions. Below this level, the mutant peak is at the level of the background or completely absent. % M denotes percent of mutant DNA; () denotes SNP at position 2361. B. LNA-PCR/sequencing. With the introduction of the LNA probe, only the mutant peak (T) is seen at position 2369 (arrow) at all dilutions of 0.8% and above. At progressively lower concentrations, the WT peak becomes visible but the mutant peak remains predominant down to 0.1% (percentages have been rounded). At the SNP position () only G is seen with complete suppression of the WT allele.