Quantitative Heteroduplex Analysis (Editorial‪)‬

General DNA analysis includes detection of targets, as well as identification and quantification of specific variants. Genomic DNA exists in the form of homoduplexes, with all corresponding base pairs being complementary, A:T and C:G. We call a double-stranded DNA (dsDNA) molecule a heteroduplex when it contains any noncomplementary base pairs. Conformational and thermodynamic changes produced by mismatched bases facilitate the detection of heteroduplexes. Denaturation of samples followed by hybridization to promote heteroduplex formation has been used to screen diploid DNA for heterozygous variations. This form of heteroduplex analysis has focused on detection, and although it may involve a quantitative threshold, the result is essentially binary. Recent work in this area (1) and elsewhere (2) has explored new implementations and applications for a more truly quantitative form of heteroduplex analysis. One setting in which heteroduplexes commonly arise is during PCR. Although the extension process of PCR replicates genomic homoduplexes with high accuracy, if the original sample is heterozygous, heteroduplexes arise during the plateau stage when dsDNA is more likely to be formed by hybridization than extension. Denaturation and hybridization associates complementary and nearcomplementary strands almost randomly. Any of various methods (listed below) that can detect the presence of heteroduplexes can then be used to detect heterozygous sequence variations.