Apart from Sanger's direct sequencing methodology, techniques to scan sequences for new mutations take advantage of several unique properties of DNA.39,51-54 One group of procedures relies on differences in electrophoretic mobilities of wild-type and mutant alleles. Single-strand conformation polymorphism (SSCP), denaturing gradient gel electrophoresis (DGGE or TGGE), and hetero-duplex analysis (HET or HA) belong to this group. A second group relies on the ability of proteins or chemicals to recognize a change in double-stranded DNA at the site of a sequence mismatch. Ribonuclease A cleavage (RNase), chemical cleavage of mismatch (CCM), and enzymatic mismatch cleavage (EMC) rely on this principle. A third group is distinguished by reliance on hybridization or hydridization combined with enzyme-based extension.39 Methods that use scanning and resequencing on microarrays and enzymatic extension from microarrays belong in this group. The protein truncation test (PTT) does not fit into any of the groups as it uses in vitro transcription and translation to detect truncation mutations.
Was this article helpful?