Rapid denaturing high-performance liquid chromatography (DHPLC) for mutation scanning of the transforming growth factor β3gene using a novel proof-reading polymerase

Determination of DNA mutation load in human tissues using denaturing HPLC-based heteroduplex analysis

Since its introduction more than a decade ago, denaturing HPLC has been widely used to screen nuclear and mitochondrial DNA for mutations. We recently developed a quantitative method based on denaturing HPLC to measure DNA mutation load, using tRNA Leu(UUR) region of the mitochondrial DNA as an example. The mutation load is determined based on the quadratic function that governs DNA reannealing and the formation of heteroduplex and homoduplex DNAs. We have used this assay to measure heteroplasmy level for several mitochondrial mutations in DNAs obtained from human tissue samples. This quantitative DHPLC assay is well suited for simultaneous detection and quantification of DNA mutations.

Quantitative Mitochondrial DNA Mutation Analysis by Denaturing HPLC

Background: In recent years, denaturing HPLC (DHPLC) has been widely used to screen the whole mitochondrial genome or specific regions of the genome for DNA mutations. The quantification and mathematical modeling of DHPLC results is, however, underexplored.

Methods: We generated site-directed mutants containing some common mutations in the mitochondrial DNA (mtDNA) tRNA(leu) region with different mutation loads and used PCR to amplify the gene segment of interest in these mutants. We then performed restriction digestion followed by slow reannealing to induce heteroduplex formation and analyzed the samples by use of DHPLC.

Results: We observed a quadratic relationship between the heteroduplex peak areas and mutant loads, consistent with the kinetics of heteroduplex formation reported by others. This was modeled mathematically and used to quantify mtDNA mutation load. The method was able to detect a mutation present in a concentration as low as 1% and gave reproducible measurements of the mutations in the range of 2.5%–97.5%.

Conclusion: The quantitative DHPLC assay is well suited for simultaneous detection and quantification of DNA mutations.