Gene Therapy
Definition:
Gene therapy is a type of treatment that uses genes to treat or prevent disease.1 Gene therapy works by putting genetic material into cells to make up for abnormal genes or to make a helpful protein. If a gene is inserted into a cell by itself, it is not helpful. In order to work, the therapy needs a reliable way to get the gene into the cell. This mode of transportation is called a “gene transfer vector.” It is genetically engineered and serves as a carrier for the gene into the cell. The gene transfer vector needs to carry the gene into the cell without causing any negative effects.2 Some viruses are vectors that invade cells; therefore an individual is injected with a virus that is carrying the genetic material. The affected individual has the virus injected into the specific organ or is given the solution intravenously. There are several different ways that researchers are testing gene therapy. One way is that they are replacing the mutated gene that causes the disease with a copy of a healthy gene. Another way is making the mutated gene inactive or “knocking it out.” The final way is that an entirely new gene is introduced to the body in order to help fight whatever disease the individual has.1
Types:
There are two main types of gene therapy in humans: germ-line and somatic. In germ-line gene therapy, the new gene is inserted into the parent’s egg and sperm cells (germ cells) in order to pass on the introduced changes to their offspring as well as keep the changes for themselves. This technique should cure the injected individual as well as their children. In somatic gene therapy, the gene is introduced to the body of the individual, but the change is not passed on to the next generation. 1
History:
The idea of gene therapy initially began in the 1960’s and 1970’s. The first case of gene therapy in mammals was when a mouse egg that was genetically “dwarf” was injected with the correct gene for normal growth. The first gene therapy trial in humans was completed by Dr. French Anderson and focused on adenosine deaminase deficiency (ADA). ADA is an infection that leaves the individual unable to fight off infections. The patient was a four year old female, who underwent gene therapy for this disorder on September 14, 1990. Her white blood cells were taken out and the normal genes for making adenosine deaminase were inserted into them via a retrovirus as a vector. Those “corrected” white blood cells were allowed to grow and were then reinserted into the female. She underwent this procedure many times for two years. Today, the patient is able to attend school and lead a normal life. In 1993, researchers were able to use gene therapy to treat newborn babies with ADA deficiency using their umbilical cord blood.2
Today’s Situation/Diseases treated by this technique:
Gene therapy is experimental and is not a current mode of treatment for disease. However, the goal is to eventually be able to use it in the future to treat or prevent diseases instead of using drugs or surgeries. It is only being tested on diseases that have no known cure. Many studies are investigating the safety and usefulness of gene therapy as well as the risks to patients.1 Genetic diseases, HIV/AIDS, and cancer are some of the diseases that gene therapy is being researched.
Gene therapy is controversial for many reasons. Using viruses as gene transfer vectors could cause detrimental effects to the individual’s body. They could cause toxicity as well as immune and inflammatory responses. While it could prevent a family from having children with a genetic disorder, but there could be unknown side effects that are detrimental to the fetus as well. Also, the unborn fetus does not have a say in whether or not they would want this procedure done to them. For these reasons, the United States does not allow federal funds to be used for human germline gene therapy research.3 The U.S. Food and Drug Administration has not approved any gene therapy products for sale in the US.
Gene therapy is a type of treatment that uses genes to treat or prevent disease.1 Gene therapy works by putting genetic material into cells to make up for abnormal genes or to make a helpful protein. If a gene is inserted into a cell by itself, it is not helpful. In order to work, the therapy needs a reliable way to get the gene into the cell. This mode of transportation is called a “gene transfer vector.” It is genetically engineered and serves as a carrier for the gene into the cell. The gene transfer vector needs to carry the gene into the cell without causing any negative effects.2 Some viruses are vectors that invade cells; therefore an individual is injected with a virus that is carrying the genetic material. The affected individual has the virus injected into the specific organ or is given the solution intravenously. There are several different ways that researchers are testing gene therapy. One way is that they are replacing the mutated gene that causes the disease with a copy of a healthy gene. Another way is making the mutated gene inactive or “knocking it out.” The final way is that an entirely new gene is introduced to the body in order to help fight whatever disease the individual has.1
Types:
There are two main types of gene therapy in humans: germ-line and somatic. In germ-line gene therapy, the new gene is inserted into the parent’s egg and sperm cells (germ cells) in order to pass on the introduced changes to their offspring as well as keep the changes for themselves. This technique should cure the injected individual as well as their children. In somatic gene therapy, the gene is introduced to the body of the individual, but the change is not passed on to the next generation. 1
History:
The idea of gene therapy initially began in the 1960’s and 1970’s. The first case of gene therapy in mammals was when a mouse egg that was genetically “dwarf” was injected with the correct gene for normal growth. The first gene therapy trial in humans was completed by Dr. French Anderson and focused on adenosine deaminase deficiency (ADA). ADA is an infection that leaves the individual unable to fight off infections. The patient was a four year old female, who underwent gene therapy for this disorder on September 14, 1990. Her white blood cells were taken out and the normal genes for making adenosine deaminase were inserted into them via a retrovirus as a vector. Those “corrected” white blood cells were allowed to grow and were then reinserted into the female. She underwent this procedure many times for two years. Today, the patient is able to attend school and lead a normal life. In 1993, researchers were able to use gene therapy to treat newborn babies with ADA deficiency using their umbilical cord blood.2
Today’s Situation/Diseases treated by this technique:
Gene therapy is experimental and is not a current mode of treatment for disease. However, the goal is to eventually be able to use it in the future to treat or prevent diseases instead of using drugs or surgeries. It is only being tested on diseases that have no known cure. Many studies are investigating the safety and usefulness of gene therapy as well as the risks to patients.1 Genetic diseases, HIV/AIDS, and cancer are some of the diseases that gene therapy is being researched.
Gene therapy is controversial for many reasons. Using viruses as gene transfer vectors could cause detrimental effects to the individual’s body. They could cause toxicity as well as immune and inflammatory responses. While it could prevent a family from having children with a genetic disorder, but there could be unknown side effects that are detrimental to the fetus as well. Also, the unborn fetus does not have a say in whether or not they would want this procedure done to them. For these reasons, the United States does not allow federal funds to be used for human germline gene therapy research.3 The U.S. Food and Drug Administration has not approved any gene therapy products for sale in the US.
- National Institutes of Health. How does gene therapy work? Accessed on July 5, 2016 https://ghr.nlm.nih.gov/primer/therapy/procedures
- National Institutes of Health. Gene Therapy. Accessed on July 6, 2016 https://history.nih.gov/exhibits/genetics/sect4.htm
- National Institues of Health. What are the ethical issues surrounding gene therapy? Accessed on July 6, 2016 https://ghr.nlm.nih.gov/primer/therapy/ethics