Automated Constant Denaturant Capillary Electrophoresis Applied for Detection of KRAS Exon 1 Mutations

In this study, we have applied automated constant denaturant capillary electrophoresis (ACDCE) for the detection of KRAS exon 1 mutations. Samples from 191 sporadic colon carcinomas previously analyzed for KRAS mutations with allele-specific PCR (ASPCR), temporal temperature gradient electrophoresis (TTGE), and constant denaturant capillary electrophoresis (CDCE) were analyzed. In ACDCE, an unmodified ABI PRISM™ 310 genetic analyzer with constant denaturant conditions separated fluorescein-labeled PCR products. Temperature in combination with a chemical denaturant was used for separation. The optimal separation conditions for PCR-amplified KRAS exon 1 fragments were determined by adjusting the temperature before electrophoresis. In the ACDCE analysis, the sequence of a mutant was determined by comparing the electropherogram of the fragment to that of known mutations followed by mixing the sample with control mutations before reanalysis. In a titration experiment mixing mutant and wild-type alleles, the sensitivity for mutation detection was shown to be 0.6% in this automated CDCE technique. The automation of CDCE allowed rapid analysis of a large number of test samples over as short period of time and with a commercially available apparatus.