Gene therapy may have the potential to fix or replace genetic mutations, which are changes in your DNA that affect how your body works.

Doctors use gene therapy, also called gene editing to directly alter your genes.

This approach may help treat diseases caused by a single mutation, such as beta-thalassemia or spinal muscular atrophy (SMA). Gene editing may also help treat certain cancers.

Gene editing tools such as CRISPR-Cas9 are very new and are rapidly changing. Researchers continue to study their full potential along with any risks they may pose.

Heres what experts know so far about gene therapy.

Genes are small segments of DNA that instruct your cells to make certain proteins when specific conditions are met.

Mutated genes, on the other hand, may cause your cells to make too much or too little of the necessary protein. Even small changes can have a domino effect across your body just as tiny changes in computer code can affect an entire program.

Gene therapy can address this issue by:

Scientists dont have tweezers small enough to edit your DNA by hand. Instead, they recruit a surprising ally to work on their behalf: viruses.

Typically, a virus would enter your cells and alter your DNA to create more copies of itself. But scientists can switch out this programming with their own, hijacking the virus to heal instead of harm. These vectors, as theyre called, dont have the parts they need to cause disease, so they cant make you sick the way a regular virus could.

There are two types of gene therapy:

Each type has its own benefits:

Gene therapy is different from genetic engineering, which means changing otherwise healthy DNA for the purpose of enhancing specific traits. Hypothetically, genetic engineering could potentially reduce a childs risk of certain diseases or change the color of their eyes. But the practice remains highly controversial since it hovers very close to eugenics.

Gene therapy may be used to treat a variety of genetic conditions, including:

When the RPE65 gene in your retinas doesnt work, your eyeballs cant convert light to electrical signals.

The gene therapy Luxturna, approved by the Food and Drug Administration (FDA) in 2017, can deliver a functional replacement of the RPE64 gene to your retinal cells.

The FDA-approved Hemgenix can treat the bleeding disorder hemophilia B. The viral vector instructs your liver cells to create more of the factor IX protein, which helps your blood clot.

Meanwhile, the gene therapy Zynteglo, approved by the FDA in 2022, treats beta-thalassemia by giving your bone marrow stem cells correct instructions for creating hemoglobin.

This blood disorder can lower the oxygen in your body because it decreases your bodys hemoglobin production.

In infantile-onset SMA, an infants body cant make enough of the survival of motor neuron (SMN) proteins necessary to build and repair motor neurons. Without these neurons, infants gradually lose their ability to move and breathe.

The gene therapy Zolgensma, approved by the FDA in 2019, replaces faulty SMN1 genes in an infants motor cells with genes that can create enough SMN proteins.

Your ABCD1 gene produces an enzyme that breaks down fatty acids in your brain. If you have cerebral adrenoleukodystrophy, this gene is either broken or missing.

Skysona, FDA approved as of 2022, delivers a functional ABCD1 gene so that fatty acids dont build up and cause brain damage.

The FDA has approved gene therapies to treat multiple types of cancer, such as non-Hodgkins lymphoma and multiple myeloma.

Most cancer gene therapies work indirectly by inserting new genes into a powerful antibody called a T cell. Your changed T cells can then latch on to cancerous cells and eliminate them, similar to how they attack viruses.

The therapy Adstiladrin, approved by the FDA in 2022, can treat nonmuscle-invasive bladder cancer by altering the DNA in your bladder cells themselves.

Some people considering gene therapy may feel uneasy about putting viruses in their body.

Keep in mind, though, that gene therapies undergo extensive testing before approval. The viruses in gene therapies are also fixed so they cant replicate similar to many vaccines.

That said, gene therapies may pose other risks:

Despite these issues, experts generally believe gene therapy offers more benefits than risks.

Most of the conditions treated with gene therapy are life threatening. The dangers of leaving them untreated often outweigh the risks of potential side effects.

Gene therapy does come with a few drawbacks that keep it from becoming a widespread treatment.

Gene therapy can only target certain mutations. This means it may not work for everyone with a specific condition.

For example, two people may have inherited vision loss. Currently, gene therapy can only treat vision loss caused by the RPE64 mutation.

Because gene therapy research is so new, experts do extensive safety testing before introducing their treatments to the public. It can take years to get FDA approval for each new therapy.

As you might imagine, gene therapies are expensive to manufacture and administer. This not only affects funding for clinical trials but also the price of the drug.

For example, the gene therapy Zolgensma is the most expensive drug in the United States at $2.1 million per dose. Even with insurance, that kind of price tag remains out of reach for the average American.

Scientists are trying to find ways to make the development process safer, cheaper, and more efficient so more people can access gene therapy.

Gene therapy works to treat several different genetic diseases by editing the mutations that cause them. As researchers further refine and expand this technology, they may find even more conditions that could be treated with it.

Experts are also continuing to explore options to make gene therapy more affordable so people who need these treatments have an easier time getting them.

Emily Swaim is a freelance health writer and editor who specializes in psychology. She has a BA in English from Kenyon College and an MFA in writing from California College of the Arts. In 2021, she received her Board of Editors in Life Sciences (BELS) certification. You can find more of her work on GoodTherapy, Verywell, Investopedia, Vox, and Insider. Find her on Twitter and LinkedIn.

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How Does Gene Therapy Work? Types, Uses, Safety - Healthline