Titration of Variant DNA Sequences Differing by a Single Point-mutation by Selective Dot-blot Hybridization with Synthetic Oligonucleotides

A dot-blot hybridization procedure with synthetic oligonucleotide probes is reported, which allows the quantitative titration in genomic DNA of variant forms of repeated genes differing by a single nucleotide change. It involves the utilization of a pair of 22-base long oligonucleotides matching the two variant sequences and the choice of an hybridization temperature very close to the Td of the oligonucleotide/DNA duplexes. The selectivity is achieved through a competition between the cognate labeled and the non-cognate unlabeled probes in the hybridization mixture.