Gene replacement therapy is a technique that alters the genes in the body’s cells to treat or prevent a disease. The technique can replace a defective gene or add a new one. For instance, p53 is a gene that can prevent the growth of tumors. Problems with the p53 gene can lead to cancer. Therefore, cancer can be eliminated in the body if the defective p53 is replaced. The immune system can recognize diseased cells, with gene therapy being used to train the immune system to spot a threat.

It is currently on a clinical trial, with researchers testing several approaches. These approaches involve introducing a new gene into the body to treat disease or inactivating an improperly functioning mutated gene. Another approach is introducing a new copy of a gene to take the place of a disease-causing gene that has mutated. This experimental technique promises to treat diseases such as some types of cancer, myotubular myopathy (disease affecting skeletal muscles), and blindness caused by retinitis pigmentosa. Others include cystic fibrosis, viral infections, diabetes, heart disease, AIDS, haemophilia, and inherited disorders. It is still thought to be risky and only being considered for diseases without a cure.

Also Known As

  • Gene therapy


Genes & Vectors

Genes, which are made up of DNA, are the basic physical and functional units of heredity. In the laboratory, scientists design new, working, human genes that give cells the necessary instructions to make a protein that may be missing or lacking in quantity. Scientists design these genes according to the disease that should be treated.

Vectors are carriers genetically engineered and delivered into the cell since a gene inserted directly does not function. Certain viruses are modified to prevent them from causing diseases and then used as vectors. The Adenovirus is one example whose DNA is introduced into a cell’s nucleus without the DNA’s integration into a chromosome. On the other hand, is the example of a retrovirus whose DNA may get integrated into a chromosome in the cell. The vector can be administered intravenously or directly injected into specific body tissue. Another way is to draw a cell sample, expose it to the vector in the laboratory, and put it back into the patient. The vector then makes a functioning protein should the treatment turn out successful.

Other vectors besides viruses include:

  • Stem cells which are lab-trained to develop disease-fighting abilities. All other body cells are created from stem cells.
  • Liposomes (fatty particles) which can carry new genes to the target cells. They then relay those genes to the DNA.


How Gene Replacement Therapy Works

The scientist:

  • Creates a new, functional copy of a dysfunctional or missing gene.
  • Places the new gene inside a vector.
  • Places the vector in the body, which then transports the new gene to the nucleus.


The body receives instructions from the new gene on how to make the protein it needs. The body then breaks down the rest of the vector.

Risks, Side Effects & Complications

Potential risks of gene replacement include:

  • Serious side effects like toxicity
  • Ensuring that the body precisely controls the new genes
  • Finding reliable methods that can place genetic material into the cells
  • The virus’ ability to cause an infection once it has been introduced into the body
  • Tumors may develop due to the insertion of the new genes into the wrong DNA spot
  • Wrong cells being targeted, which may cause other diseases like cancer. Viruses that have been altered may infect additional cells instead of only the targeted cells that carry mutated genes.
  • Inflammation and/or organ failure since the gene is delivered to the body via a vector (viruses). The viruses may be mistaken for intruders and get attacked by the body’s immune system.



Individuals who wish to undergo gene replacement therapy are advised to participate in a clinical trial. A clinical trial assists doctors to establish the safety of gene therapy in people. Doctors also get to comprehend what effects gene therapy has on the body. Other reasons for undertaking a clinical trial are determining which diseases gene therapy can cure and whether it is an effective treatment option.

One of the fundamental concerns is that the treatment is new and may have unpredictable risks. Therefore, every attempt is being taken to make the procedure as safe as possible for those opting for the trial. Therefore, the trial is closely monitored by the Food and Drug Administration, other medical researchers, and institutions. An individual’s specific condition determines the specific procedure and gene therapy type to be used. Those interested in participating can speak to their doctors.

Ethical Concerns

Some people have raised issues with the ethics surrounding gene replacement therapy because it involves altering the body’s basic instructions. Concerns range from, distinguishing between acceptable and unacceptable uses of gene replacement therapy, who decides which traits are normal, issues regarding cost and inequality, whether patients who have undergone the procedure will not be stigmatized, etc. Spiritual concerns revolve around whether human beings are allowed to alter basic human traits like intelligence and height.