DNA is the blueprint determining the characteristics of living organisms. Genes are specific segments of DNA and each gene encodes a product with a biological effect.
Sometimes, individual genes may become defective, leading to disease manifestations. Many diseases including cystic fibrosis, severe combined immunodeficiency (SCID), thalassemia, and sickle-cell anaemia are the result of just one malfunctioning gene.
Gene therapy has the potential to treat these genetic diseases. In a nut shell, it consists of the following steps:
The gene responsible for the disease is identified
- Functional copies of the gene are made available. In principle, cells from a healthy person can be removed and the specific gene isolated. Copies of this functional gene can then be made in the laboratory.
- Target cells bearing the “faulty” gene are removed from the patient.
- A carrier (also known as the vector) is used to insert a copy of the functional gene into the DNA of target cells. Currently, the most common type of vectors are viruses. These viral vectors are genetically engineered to replace their disease-causing genes with the therapeutic genes.
- The target cells now bear two copies of the gene – the original, faulty copy, as well as the newly introduced functional copy. These target cells are reintroduced into the patient’s body.
- The newly introduced gene functions on behalf of the original, faulty one, leading to alleviation of disease symptoms.
Gene therapy holds great promise for a variety of diseases. However, the technology is currently still experimental and no human gene therapy product has been approved for routine clinical use.