Gene Therapy

Summary

Gene therapy aims to treat genetic disorders by changing the genetic material in a patient’s cells. For diseases caused by a defective single gene, one approach is to add a working copy of the gene so cells can produce the needed protein. Gene therapy may also introduce a new gene or disable a mutated one.

The video describes a treatment strategy for a form of severe combined immunodeficiency (SCID), in which bone marrow cells cannot produce an essential enzyme. Because bone marrow stem cells generate blood and immune cells, modifying these stem cells may provide lasting benefits as they divide.

Example method: Retroviral gene delivery

1. Create a copy of the normal version of the gene.
2. Place the gene in a retroviral vector. Retroviruses can convert their RNA genome into DNA and insert that DNA into a host cell’s genome.
3. Remove bone marrow cells from the patient and expose them to the virus carrying the normal gene.
4. Return the modified cells to the patient’s bone marrow.
5. As the cells divide, they can produce the essential enzyme, potentially alleviating the disorder.

Other approaches and challenges

Gene therapy can add a normal allele to compensate for a defective one, introduce a completely new gene, or inactivate a mutated gene. DNA can also be delivered without a virus, including through electroporation, which temporarily makes cell membranes more permeable, or by direct injection using very fine needles.

A key technical challenge is that viral DNA may insert at unpredictable locations in the genome. It can also be difficult to control how the introduced gene is expressed. Despite these complications, gene therapy has shown significant success in treating some serious genetic diseases and remains an active area of study.

Ethical considerations

Gene therapy raises questions about modifying a person’s genome. The video compares it with blood donations and organ transplants, which also introduce living cells containing foreign DNA, while acknowledging that genetic modification may raise distinct concerns.

One major concern is that the technology could be used to engineer people or control the genetic makeup of a population, potentially leading to eugenics. The central lesson is to balance scientific progress with great caution and consider the ethical consequences before such technologies become widespread.

Speaker featured

• Professor Dave — narrator and presenter.