Getting to Know Gene Therapy: Terminology and Concepts

What is gene therapy?

Gene therapy is introduction of DNA into a patient to treat a genetic disease or a disorder. The newly inserted DNA contains a correcting gene to correct the effects of disease causing mutations. Gene therapy is promising treatment for the genetic diseases and also includes cystic fibrosis and muscular dystrophy. Gene therapy is suitable treatment for the infectious diseases, inherited disease and cancer.

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Diseases Treated by Gene Therapy

Gene Therapy was initially meant to introduce genes straight into human cells, focusing on diseases caused by single-gene defects, such as cystic fibrosis, hemophilia, muscular dystrophy and sickle cell anemia. Three types of diseases for gene therapy can be distinguished:

  • Monogenic disorders, single locus (gene) is defective and responsible for the disease, 100% heritable. Examples: Sickle cell anemia, Severe Combined Immunodeficiency (ADA-SCID / X-SCID), Cystic fibrosis, Hemophilia, Duchenne muscular dystrophy, Huntington’s disease, Parkinson’s, Hypercholesterolemia, Alpha-1 antitrypsin, Chronic granulomatous disease, Fanconi Anemia and Gaucher Disease.
  • Polygenic disorders, multiple genes involved, disease may be dependent on environmental factors and lifestyle. Examples: Heart disease, Cancer, Diabetes, Schizophrenia and Alzheimer’s disease.
  • Infectious diseases, such as HIV.

How does gene therapy work?

Gene therapy 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.

A gene that is inserted directly into a cell usually does not function. Instead, a carrier called a vector is genetically engineered to deliver the gene. Certain viruses are often used as vectors because they can deliver the new gene by infecting the cell. The viruses are modified so they can't cause disease when used in people. Some types of virus, such as retroviruses, integrate their genetic material (including the new gene) into a chromosome in the human cell. Other viruses, such as adenoviruses, introduce their DNA into the nucleus of the cell, but the DNA is not integrated into a chromosome.

The vector can be injected or given intravenously (by IV) directly into a specific tissue in the body, where it is taken up by individual cells. Alternately, a sample of the patient's cells can be removed and exposed to the vector in a laboratory setting. The cells containing the vector are then returned to the patient. If the treatment is successful, the new gene delivered by the vector will make a functioning protein.

Researchers must overcome many technical challenges before gene therapy will be a practical approach to treating disease. For example, scientists must find better ways to deliver genes and target them to particular cells. They must also ensure that new genes are precisely controlled by the body.

I hope this article was helpful regarding gene therapy ? and I am sure you’ll have more questions.

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