Native DNA PAGE gels can be used to detect small mutational differences between DNA molecules. In heteroduplex analysis, for double stranded DNA, the basis of separation is the conformational difference arising from the bending of the rodlike double helix caused by small mismatches between the strands. In SSCP analysis, single stranded DNA molecules are fractionated based on the compactness of their folded structure. In both cases, it is possible to separate strands of equal length which have different sequences, often differing by only one base. Given a control (unmutated) fragment to use as a gel standard, these techniques can be used to screen large numbers of samples for mutations.

NEXT TOPIC: Heteroduplex Analysis