FIGURE 1.

The expanding Gene Therapy field. Originally gene therapy was envisioned as the in situ modification of genetic information of cells within tissues. The field has evolved beyond that encompassing more aspects of nucleic acid technology, particularly oligonucleotide technology, which aims to modify gene expression, without necessarily changing the cell's genetic information. The modification of a patient's cells ex vivo, outside the body prior to reimplantation has proven to be a successful clinical strategy. Although recent technological advancements have now enabled mitochondrial and germ line or embryonic cell gene therapy, these approaches are not yet being used due to safety and ethical issues.