Abstract: The present invention relates to using single-stranded oligonucleotides that are designed to specifically change a base in a target nucleic acid sequence. This alteration is maintained, expressed and regulated as the normal endogenous gene.

Abstract: This invention provides methods for modifying a selected gene in cells of a mammalian skin at one or more locations by delivering to the skin cells an effective amount of a composition having a chimeric RNA-DNA oligonucleotide for causing heritable modifications in the selected gene so that the heritable modifications result in phenotypic changes at the locations of the mammalian skin. The invention specifically provides a method for permanent gene correction of a gene mutation by an RNA-DNA oligonucleotide (RDO) in vivo. By this method, a point mutation in the albino BALB/c mouse tyrosinase gene in vivo has been corrected thereby providing for permanent and inheritable restoration of tyrosinase enzymatic activity, melanin synthesis, and pigmentation changes in melanocytes of skin at the treated locations. Both topical application and intradermal injection of this oligonucleotide to mice skin resulted in dark pigmentation of several hairs in localized area.

Abstract: The invention concerns the use of duplex oligonucleotides having both 2'-deoxyribonucleotides and ribonucleotides, wherein there is base pairing between the two types of nucleotides. The sequence of the oligonucleotide is selected so that the 3' and 5' most regions of the oligonucleotide are homologous with (identical to) the sequence of a preselected target gene of a cell. The two regions of homology embrace a region that is heterologous with the target sequence. The introduction of the oligonucleotide into the nucleus of the cell causes the alteration of the target gene such that the sequence of the altered target gene is the sequence of the heterologous region. Consequently, the oligonucleotides of the invention are termed Chimeric Repair Vectors (CRV). In one embodiment of the invention the target gene is a globin gene and the target cell is a hematopoietic stem cell. This embodiment can be used to correct certain hemoglobinopathies such as Sickle Cell Disease, .beta.