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Gene Therapy Basics

Gene therapy has been studied for more than 40 years and can help stop or slow the effects of disease on the most basic level of the human body—our genes. Gene therapy is the introduction, removal or change in genetic material—DNA or RNA—into the cells of a patient to treat a specific disease.

Understanding Genes

Genes are made up of DNA, which are blueprints to build proteins that make the body work. Each person typically gets two copies of each gene from their parents. These genes control everything from hair color, height, and unique traits. But genes are not always built correctly. A small change to them, called a mutation, can alter how proteins are expressed (produced), which impacts the body’s ability to function properly. This can alter the way a person breathes, walks or even digests food. Genes can change as they go through inherited mutations (changes that were passed along from the parents), as they age, or by being altered or damaged by chemicals and radiation.

How Gene Therapy Works

Gene therapy aims to be given one-time to target a faulty gene that causes disease. Gene therapy is the introduction, removal or change in genetic material— DNA or RNA—into the cells of a patient to treat a specific disease. The genetic material that is delivered has instructions to change how a protein—or group of proteins—is produced by the cell. For some diseases, this means making changes to account for too much, not enough, or incorrect essential proteins being produced within cells.

This new genetic material, such as a working gene, is delivered into the cell using a vector. Viruses can be used as vectors because they have evolved to be very good at getting into cells. But scientists have learned how to remove the viral genes and use this same ability to treat or prevent disease. In this case, their goal is to insert the new therapeutic genes into the cell. All viral vectors are tested many times for safety prior to being used. The vector can either be delivered outside the body (ex-vivo treatment) or the vectors can be injected into the body (in-vivo treatment).

Learn more about different gene therapy approaches, challenges, risks, and benefits.  


Types of Diseases for Gene Therapy

There are some FDA-approved gene therapies currently available to patients with diseases such as SMA, certain blood cancers, and an inherited eye disease. However, most gene therapies are in clinical trials. Clinical trials are a required research process to understand how a treatment interacts with the body, and if it is safe and effective before it can be made available to the public. 

Gene therapy is aimed at diseases that are rare and often life threatening or debilitating. Rare is defined as “any disease or disorder affecting fewer than 200,000 people in the U.S.” by the National Institutes of Health. As of now, there are around 7,000 rare diseases, affecting a total of approximately one in ten people. Many of these rare diseases are caused by a simple genetic mutation inherited from one or both parents.

Of gene therapies up for FDA approval over the next five years, 45 percent are anticipated to focus on cancer treatments (nearly half) and 38 percent (nearly 4 out of 10) are expected to treat rare inherited genetic disorders.  

Some of these inherited diseases include (but are not limited to): 

  • Hematology (blood) disorders like sickle cell disease 

  • Neurological disorders that affect the brain and spinal cord 

  • Musculoskeletal (muscle) diseases 

  • Retinal (eye) disorders 

  • Oncology (cancers) such as blood cancers 

Explore more resources on our website about gene therapy for specific diseases, helpful insights on the patient journey, and clinical trials information.  

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Last Updated: 07/26/2021

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