Reivindicaciones

1. An in vitro method for inducing a stable gene modification of a target nucleic acid comprising one or more mutant alleles comprising disease-causing mutations of the COL7A1 gene via homologous recombination in primary cells selected from the list consisting of keratinocytes or skin fibroblasts, wherein the method comprises introducing into the primary cells: (a) a modified single guide RNA (sgRNA) comprising a nucleotide sequence that is complementary to the target nucleic acid and a nucleotide sequence that interacts with a CRISPR-associated protein (Cas) polypeptide, wherein the RNA component can be two individual RNA molecules (crRNA and tracrRNA) or a single RNA molecule (sgRNA); (b) a Cas polypeptide, an mRNA encoding a Cas polypeptide, and/or a recombinant expression vector comprising a nucleotide sequence encoding a Cas polypeptide, wherein the modified sgRNA, or crRNA and tracrRNA components provided separately, guide the Cas polypeptide to the target genomic sequence to be corrected; and (c) a donor template DNA homologous to the genomic sequence comprising the mutation site to be repaired, carried by serotype 6 adeno-associated viral vectors (AAV-6) or carried by serotype 1 adeno-associated viral vectors (AAV-1); wherein, the stable gene modification of the target nucleic acid, based on the replacement of one or more mutant alleles comprising the disease-causing mutations of the COL7A1 gene (target nucleic acid), occurs by providing AAV-6 or AAV-1 vectors carrying the correction donor templates comprising wild-type alleles corresponding to the mutant alleles. 2. The method of claim 1, wherein the Epidermolysis Bullosa disease-causing mutations are recessive Dystrophic Epidermolysis Bullosa (RDEB) disease-causing mutations. 3. The method of any of claims 1 or 2, wherein the one or more mutant alleles comprising the disease-causing mutations of the COL7A1 gene (target nucleic acid) are located in any of exons 73, 74, 75, 80 or 105 of the COL7A1 gene, and these mutations are repaired by using a correction donor template comprising the wild type exons 73, 74, 75, 80 or 105 of the COL7A1 gene. 4. The method of any of claims 1 to 3, wherein the primary cells are isolated from a mammal, preferably from a human subject, prior to introducing the modified sgRNA, the Cas polypeptide, and the AAV-6 or AAV-1 vector carrying the homologous donor template into the primary cells. 5. The method of any of claims 1 to 4, wherein the Cas polypeptide is a Cas9 polypeptide or a variant thereof, or a fragment thereof. 6. The method of any of claims 1 to 5, wherein the donor template does not contain the Cas recognized- Protospacer Adjacent Motif (PAM) sequence, or wherein the donor template does not contain one or more intronic regions of the targeted nucleic acid. 7. The method of any of claims 1 to 6, wherein the RNA component and/or the Cas polypeptide are introduced into the primary cells by electroporation and wherein optionally the AAV-6 or AAV-1 vector carrying the homologous donor template is introduced into the primary cell by transduction. 8. The method of any of claims 1 to 7, wherein the RNA component and the Cas polypeptide are incubated together to form a ribonucleoprotein (RNP) complex prior to introducing into the primary cell and wherein optionally the RNP complex and the homologous donor AAV-6 or AAV-1 vector are sequentially introduced into the primary cells. 9. A primary cell or cell population comprising the stable gene modification of the target nucleic acid obtained or obtainable by the method of any of claims 1 to 8. 10. The cell population comprising the primary cells in accordance with claim 9, wherein said population includes at least about 30% primary keratinocytes having the stable gene modification of the target nucleic acid. 11. A pharmaceutical composition comprising the primary cells or cell population of any of claims 9 or 10. 12. In vitro use of a kit comprising (a) a modified single guide RNA (sgRNA) comprising a nucleotide sequence that is complementary to the target nucleic acid and a nucleotide sequence that interacts with a CRISPR-associated protein (Cas) polypeptide, wherein the RNA component can be two individual RNA molecules (crRNA and tracrRNA) or a single RNA molecule (sgRNA); (b) a Cas polypeptide, an mRNA encoding a Cas polypeptide, and/or a recombinant expression vector comprising a nucleotide sequence encoding a Cas polypeptide, wherein the modified sgRNA, or crRNA and tracrRNA components provided separately, guide the Cas polypeptide to the target genomic sequence to be corrected; (c) an adeno-associated viral (AAV6) or AAV-1 vector comprising a recombinant donor template comprising two nucleotide sequences comprising two non-overlapping, homologous portions of the target nucleic acid, to undergo homologous recombination, in a method for inducing a stable gene modification of a target nucleic acid comprising one or more mutant alleles comprising disease-causing mutations of the COL7A1 gene via homologous recombination in primary cells selected from keratinocytes or fibroblasts obtained from a subject, preferably a human subject. 13. The pharmaceutical composition of claim 11, or the primary cells or cell population of any of claims 9 or 10, for use in a method of preventing or treating Epidermolysis Bullosa, preferably recessive Dystrophic Epidermolysis Bullosa (RDEB), in a subject in need thereof, the method comprising administering to the subject the said composition in a sufficient amount to correct a mutation in the target nucleic acid that is associated with the disease, to prevent the disease or ameliorate one or more symptoms of the disease. 14. In vitro use of the primary cells or cell population of any of claims 9 or 10, to manufacture skin equivalents. 15. Skin equivalents obtainable or obtained according to claim 14, for use in the treatment of Epidermolysis Bullosa, particularly the recessive dystrophic subtype (RDEB).