Figure 2.

Targeted gene repair with modified single-stranded oligonucleotides. The mutant base is recognized by the single-stranded oligonucleotide, which is designed to hybridize to a region immediately surrounding the targeted base. At one specific site, a mismatch is created (C/T here) with the displacement of the complementary strand, which contains the G residue (G). DNA repair activity catalyzed by the cellular machinery inserts an A on the hybridized strand to pair with the T residue of the template. A second repair event completes the cycle by removing the G residue and replacing it with a T. In this case, a conversion of the G•C base pair to an A•T base pair results from the gene repair reaction. Reproduced with permission from Current Opinion in Molecular Therapeutics (47).