TARGETED GENE CONVERSION IN A MAMMALIAN CD34(-ENRICHED CELL-POPULATION USING A CHIMERIC RNA())DNA OLIGONUCLEOTIDE/

Gene conversion of genetically inherited point mutations is a fundamen tal methodology for treating a variety of diseases. We tested the feas ibility of a new approach using an RNA/DNA chimeric oligonucleotide. T he beta-globin gene was targeted at the point mutation causing sickle cell anemia. The chimera is designed to convert an A residue to a T af ter creating a mismatched basepair. In a CD34(+)-enriched population o f normal cells a 5-11% conversion rate was measured using restriction enzyme polymorphism and direct DNA sequence analyses. The closely rela ted delta-globin gene sequence appeared unchanged despite successful c onversion at the beta-globin locus.