Abstract: The invention provides methods permitting the detection of small amounts of different nucleic acids in the presence of an excess amount of wild-type nucleic acids. Also provided herein are method so detecting infectious disease minority variants, methods of forensic identification, methods of diagnosing cancer and monitoring disease progress.

Abstract: An oligonucleotide based therapeutic strategy, called anti-gene locks, is described which specifically kills cells based on their genotype. The strategy employs oligonucleotides with arms and a backbone that are complementary to both strands of the gene target. Anti-gene locks bind in vitro in a sequence dependent fashion and inhibit DNA synthesis. In bacterial cells containing an episome target, they cause elimination of the extra-chromosomal DNA structure. When the target is present in the bacterial or human genome, they selectively kill the majority of these cells.