Detection of ras point mutations by polymerase chain reaction using mutation-specific, inosine-containing oligonucleotide primers.

The use of DNA primers with 3'-ends complementary to specific genetic point mutations allowed for the rapid detection of such mutations in genomic DNA by polymerase chain reaction. The sensitivity of this approach was such that mutations could be detected in DNA samples mixed with a 10(7)-fold excess of normal non-mutated DNA. To increase the practicality of this approach for the detection of point mutations affecting all 3 of the known ras oncogenes we synthesized mutation-specific primers complementary to all 3 genes by substituting inosine residues at positions corresponding to ambiguous bases on the genes.