Genetic diseases are caused by a defective gene or group of genes, which are composed of DNA. A gene contains the instructions for making a specific protein or related group of proteins that control cell function. Defects in genes (i.e., errors in the instructions for making proteins) can cause the cell to make too little protein, too much protein, or a defective protein, preventing the cell from functioning properly and potentially causing disease.
Gene therapy is the treatment of genetic diseases through the delivery of corrective “therapeutic DNA” into the genetic material of a patient’s cells. The corrective DNA is packaged within a vector that is used to effectively deliver the DNA into targeted cells. Once inside the cell, the cell machinery uses the therapeutic DNA to produce functional proteins that the defective DNA could not, resulting in the correction of the underlying cause of disease pathology directly by restoring the lost function.
By contrast, traditional drug-based approaches address disease symptoms but not the underlying genetic cause. Gene therapy, however, directly targets the specific genetic defects that are the cause of the genetic disease and therefore holds tremendous promise for treating some of the most debilitating and intractable diseases.
Over the past decade, advances in the fundamental understanding of the human genome, next-generation DNA sequencing, gene synthesis technologies for high-throughput design and production of DNA constructs and libraries, and bioinformatics and computer modeling have dramatically accelerated the therapeutic potential of DNA therapeutics, ushering in a new era in gene therapy. Recent clinical achievements include the successful treatment of patients with the lipoprotein lipase deficiency, retinal disease, Leber’s congenital amaurosis, X-linked SCID and ADA-SCID, adrenoleukodystrophy, chronic lymphocytic leukemia, acute lymphocytic leukemia, multiple myeloma, hemophilia, and Parkinson’s disease.