What Is Gene Therapy?

How Gene Therapy Has the Potential to Cure Disease and Save Lives

Gene therapy, conceptual artwork
ANDRZEJ WOJCICKI/Science Photo Library/Getty Images

Genes are our body’s blueprint. They outline the way our bodies work, grow, as well as determine our physical characteristics like height and eye color. Sometimes our genes are faulty, and our body’s blueprint doesn’t turn out the way it’s supposed to. These changes can be severe, like a life-threatening illness, or completely inconsequential.

Scientists are now looking to edit genes using gene therapy, an experimental way of using genes to treat or prevent disease.

Disorders caused by mutations in a single gene are the best candidates for gene therapy. Researchers are exploring gene therapy as a way to replace abnormal disease-causing genes, activate or inactivate improperly working genes, and introduce new genes into the body to treat or cure diseases.

How Gene Therapy Works

In most gene therapy studies, a normal gene is inserted into the body to replace an abnormal gene that is causing disease. These genes are typically delivered through viruses, which scientists have manipulated in the lab so that they no longer carry any harmful or disease-causing materials. Researchers inject these viruses, known as vectors, into cells that have been taken from your body –– through a blood draw or bone marrow aspiration. Once those cells have been treated in the laboratory, they are then reintroduced into your body. Viruses aren’t the only vector that can be used for gene therapy.

Artificial lipid spheres called liposomes and specially-trained stem cells are currently being investigated.

Challenges Facing Gene Therapy

There are a number of problems with gene therapy that need to be solved before this type of treatment is approved by the Food and Drug Administration (FDA). Currently, the only way to get gene therapy is by participating in a clinical trial.

Clinical trials are only available for diseases without a cure. While gene therapy shows promise, it also faces some significant challenges, including:

  • Treatment limitations: Diseases caused by more than one gene would be difficult to treat with gene therapy.

  • Serious health risks: Studies using gene therapy have already shown that it pose serious health risks such as toxicity, inflammation, and cancer.

  • A lack of reproducibility: Although gene therapy could potentially lessen or cure a disorder, the treatment would only be effective for the person receiving treatment. If that person has children, their children can inherit the defective gene.

  • Immune response: The body’s immune system naturally attacks foreign cells, so the body may attack the genes being introduced via gene therapy or the vector. This happened in 1999, when 18-year-old Jesse Gelsinger, died during a gene therapy study for ornithine transcarbamylase deficiency. His death is believed to have been triggered by a severe immune response to the gene therapy carrier virus.

The Bottom Line

No treatment is without risks, so the risks of gene therapy must be balanced against its potential benefits.  For people living with life-threatening genetic conditions for which there is no cure, gene therapy might offer a better chance at life.

Despite its risks, researchers are still interested in studying gene therapy with the hopes of unlocking its full potential in the safest way possible.


"Gene Therapy." Human Genome Project Information. 06 Aug 2007. The Human Genome Program of the U.S. Department of Energy Office of Science. 

"Gene Therapy." Genetics Home Reference. 29 Feb 2008. U.S. National Library of Medicine.