Spinal Muscular Atrophy

Gene therapy is a fitting approach for diseases caused by a single gene mutation, like SMA. It targets the cause of disease by delivering a fully functioning copy of the gene into motor neuron cells. Here's how it works.

Spinal Muscular Atrophy (SMA) is a rare genetic disease that affects the motor nerve cells in the spinal cord and is the leading genetic cause of infant mortality. It is caused by an inherited faulty SMN1 gene. The SMN1 gene helps provide instructions to cells on how to produce the SMN (survival motor neuron) protein. If there isn’t enough correct SMN protein produced, it leads to degeneration, meaning decline or deterioration, of motor neurons. This creates problems with a person’s physical strength, often taking away the ability to walk, eat or even breathe.

Treatment Pipeline

Following years of preclinical studies and clinical trials, there are currently two gene and cell therapies to treat SMA approved for clinical use in the United States.

Zolgensma (AVXS-101)

The FDA approved Zolgensma (also known as AVXS-101), a gene therapy developed by AveXis (a gene therapy company owned by Novartis) for clinical use in the United States on children under two years of age with all types of SMA.

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For clinical trials treating SMA type 1, researchers described improvements in respiratory and movement function meaning patients were able to breathe better, feed themselves, and sit unassisted. These improvements lead to fewer and less lengthy hospitalizations compared to what patients traditionally face. These reductions in hospitalizations can help improve both the child’s and caregiver’s quality of life.


There’s an FDA-approved treatment called Spinraza that helps to counter the effects of SMA. Spinraza helps increase the production of the SMN protein by using a backup gene called SMN2. With Spinraza’s help, enough SMN protein is produced. If you think this treatment might be an option for you or your child, make an appointment with your healthcare provider to learn more and help determine eligibility.

Challenges & Benefits

One Time Treatment and Expansion


The aim for SMA gene therapy is to only need one administration by targeting the cause of the disease. Typically this should only take about an hour. This is in comparison to other treatments that may require a series of doses, multiple times throughout the patient’s life. Once a therapy is approved, then researchers begin to work on expanding it to reach patients that have other Types of SMA or that may be older than the current inclusion age.

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Early Diagnosis: Newborn Screenings


The symptoms of SMA Type 1—the most common and severe form of the disease—show up within the first six months of a child’s life. These symptoms can cause irreversible damage to a patient within this period, so early diagnosis is key to receiving an effective gene therapy treatment.

Early diagnosis can be completed through standard newborn screenings. Although progress has been made, there are still many states that do not include SMA as a part of standard screening completed for newborns. As mentioned above, it is highly important for this disease to be diagnosed as early as possible. You can help advocate for SMA to be added to the panel of newborn screenings in your state.

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Screening Before or During Pregnancy


Parents who are planning a pregnancy can learn if they are carrying genes for inherited disorders by analyzing small samples of blood or body tissues gathered from a cheek swab or blood draw. Expecting parents can also consider genetic testing during pregnancy, where pregnant women can undergo amniocentesis or chorionic villus sampling to screen for disorders. Genetic testing can also be done soon after birth.

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Eligibility and Access


If you are considering participation in a clinical trial for yourself or your child, remember that it is difficult to know if and when a clinical trials can be stopped, delayed or approved. Because of this, it can be risky to avoid other forms of care while waiting for a treatment approval. It is also important to know that certain eligibility criteria is in place, which may include being a certain age or having a certain type of SMA and the antibodies that will accept the treatment. Another complexity that has come to light recently is the potential of having an up to two year “washout” period between interventions. For example, if a patient has received Spinraza and now is considering a gene therapy there may be a two year waiting period required between them. It is best to speak with your healthcare provider to understand and maneuver this difficult decision-making process.

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Patient and Family Support


Patient advocacy organizations work hard to provide support, advice and information for getting involved. They are a great way to connect with other families affected by SMA. Although the disease may be rare, you’re not alone. For more resources and support networks, check out:

CureSMA and SMA Europe
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Cure vs. Control


While pursuing existing or future SMA gene therapy treatments, it is important to note that gene therapy is not a cure and instead helps to control the progression of the disease. It’s impossible to restore already damaged neurons in a patient. However, gene therapy can help slow or stop the effects of the disease, greatly increasing the quality of life for the child as they grow older.

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Developing A Treatment

How do clinical trials work? Gene therapies take years to go from theoretical concepts, to preclinical trials, to clinical trials, and, finally, into actual treatments that can improve the lives of patients. Here we learn about the process of developing a treatment.

Different Approaches

Gene therapy, cell therapy and gene editing are fields with a similar goal: To treat disease by changing our bodies at a microscopic level. What do these approaches have in common, and what makes them different?

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. And to understand how it works, we’ll start at the basics.


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