Question

Genetics:

How does gene therapy work?

What are the challenges of gene therapy?

Identify a disease state that could be treated with gene therapy.

There are several ethical issues surrounding gene therapy. Pick one and state whether you agree or disagree with the position. Explain your answer.

There are both highs and lows in gene therapy. Research the stories of Ashanti de Silva and Jesse Gelsinger. Based on the outcomes of these treatments, do you think experimental gene therapy trials should continue? Why or why not?

Answer 1

How does gene therapy work?
Gene therapy is an experimental technique that uses genes to treat or prevent disease. In the future, this technique may allow doctors to treat a disorder by inserting a gene into a patient's cells instead of using surgery or drugs. In most gene therapy, a "normal" gene is inserted into the genome to replace an "abnormal," disease causing gene. In cancer, some cells become diseased because certain genes have been permanently turned off. Using gene therapy, mutated genes that cause disease could be turned off so that they no longer promote disease, or healthy genes that help prevent disease could be turned on so that they can inhibit the disease.
Gene therapy is the addition of new genes to a patient's cells to replace missing or malfunctioning genes. It is designed to introduce genetic material into cells to compensate for abnormal genes or to make a beneficial protein. If a mutated gene causes a necessary protein to be faulty or missing, gene therapy may be able to introduce a normal copy of the gene to restore the function of the protein.

What are the challenges of gene therapy?
Gene therapy has some potential risks. A gene can't easily be inserted directly into your cells. Rather, it usually has to be delivered using a carrier, called a vector. The most common gene therapy vectors are viruses because they can recognize certain cells and carry genetic material into the cells' genes. The immune system may respond to the working gene copy that has been inserted by causing inflammation. The working gene might be slotted into the wrong spot. The working gene might produce too much of the missing enzyme or protein, causing other health problems. After initially receiving a type of gene therapy, the patient's immune system may react to the foreign vector, causing fever, severe chills (called rigors), drop in blood pressure, nausea, vomiting, and headache. These symptoms typically resolve within 24-48 hours of the infusion.

Identify a disease state that could be treated with gene therapy.
Gene therapy is the introduction of genes into existing cells to prevent or cure a wide range of diseases. The same gene therapeutic techniques have been applied to treat other acquired disorders such as viral infections (e.g. influenza, HIV, hepatitis), heart disease and diabetes, among others. Some of these have entered, or will soon be entering, into early phase clinical trials. With its potential to eliminate and prevent hereditary diseases such as cystic fibrosis and hemophilia and its use as a possible cure for heart disease, AIDS, and cancer, gene therapy is a potential medical miracle worker.

There are several ethical issues surrounding gene therapy. Pick one and state whether you agree or disagree with the position. Explain your answer.
Genetic research has advanced in a dramatic fashion in the last decade or so, to the point where it has now become possible to attempt therapeutic genetic modification, in a few cases of human genes, where a defects exists which manifests itself in certain serious diseases. Currently gene therapy research has focused on treating individuals by targeting the therapy to body cells such as bone marrow or blood cells. This type of gene therapy cannot be passed to a person’s children. Gene therapy could be targeted to egg and sperm cells (germ cells), however, which would allow the inserted gene to be passed to future generations. This approach is known as germline gene therapy. Because gene therapy involves making changes to the body’s set of basic instructions, it raises many unique ethical concerns. The ethical questions surrounding gene therapy include:

• How can “good” and “bad” uses of gene therapy be distinguished?
• Who decides which traits are normal and which constitute a disability or disorder?
• Will the high costs of gene therapy make it available only to the wealthy?
• Could the widespread use of gene therapy make society less accepting of people who are different?
• Should people be allowed to use gene therapy to enhance basic human traits such as height, intelligence, or athletic ability?

The idea of germline gene therapy is controversial. While it could spare future generations in a family from having a particular genetic disorder, it might affect the development of a fetus in unexpected ways or have long-term side effects that are not yet known. Because people who would be affected by germline gene therapy are not yet born, they can’t choose whether to have the treatment.