What is Spinal Muscular Atrophy (SMA)?

Following our last post about Spinal Muscular Atrophy (SMA), our daughter Gwendolyn, and our passionate drive to END SMA, we realized there is much confusion about what the disease actually is, how it is caused, and issues surrounding the disease. We are encouraged by the active discussion and think it is proof positive of the need to further SMA awareness – a major part of the mission of the http://GwendolynStrongFoundation.org. So with our second post, we would like to clarify some of those issues and we hope you will take the time to learn more about the #1 genetic killer of young children, SMA!!!

For more information or to make a donation to help END SMA, please visit http://GwendolynStrongFoundation.org

SMA Statistics

  • SMA kills more children than any other genetic disease.
  • SMA is estimated to occur in 1 out of every 6,000 births.
  • 1 in every 35 people, or nearly 10 million Americans, UNKNOWINGLY carries the gene responsible for SMA. Few have any known family history.
  • SMA is a pan-ethnic disease and does not discriminate based on race, ethnicity, or gender.
  • There is currently no treatment and no cure, but the National Institutes of Health (NIH) selected SMA as the disease closest to treatment of more than 600 neurological disorders.
  • 50 of the nations leading researchers signed a statement stressing that a viable treatment and/or cure is attainable in as little as 5 years - IF provided adequate resources.
  • SMA is considered a “model” disease, with the potential for enormous benefit to millions of people impacted by other diseases, including ALS/Lou Gehrig’s, Alzheimer’s, Parkinson’s, Duchenne Muscular Dystrophy, Fragile X, Tay Sachs Sandhoff, among others.
  • The American College of Medical Genetics recommends that SMA carrier testing be made available to ALL couples planning a family, regardless of ethnicity or family history. Due to a lack of awareness, most families do not currently know to ask for it and OBGYNs have yet to routinely offer it.

What is SMA?
Most babies with SMA are born after a normal pregnancy, are seemingly healthy, and pass all current newborn screenings. SMA is a terminal and degenerative disease that causes weakness and wasting of the voluntary muscles in infants and children. Specifically, the disease is caused by an abnormal or missing gene known as the survival motor neuron gene (SMN1), which is responsible for the production of a protein essential to motor neurons. Without this protein, lower motor neurons in the spinal cord degenerate and die. As the motor neuron network breaks down, the ability of the brain to control muscles diminishes and with less control and use, muscles weaken and waste away. Simply, SMA eventually impacts every muscle in the body hindering the ability to walk, sit, stand, eat, breathe, and swallow. The mind always remains unaffected and children with SMA are bright, sensitive, and playful in spite of their failing bodies.

How does SMA occur?
Approximately 1 in 35 people, or nearly 10 million Americans, unknowingly carries the gene responsible for SMA. These people are referred to as “carriers.” Non-carriers have two healthy copies of the SMN1 gene. But, carriers have one healthy SMN1 copy and one defective, mutated SMN1 copy. The one healthy SMN1 gene is more than sufficient to direct the production of SMN protein in carriers. However, when two carriers have a child, that child randomly gets one SMN1 gene from each parent: 25% of the time that child receives two healthy SMN1 genes (one from each parent); 50% of the time that child gets one healthy SMN1 gene and one defective SMN1 gene; and 25% of the time that child gets two defective SMN1 genes. It is this last 25%, where the child is passed two defective, mutated SMN1 genes, in which the active form of SMA occurs and the child is left without the functioning SMN1 gene that is responsible for the production of a protein essential to motor neurons. Most couples that have a child with SMA had no known prior family history and carriers exhibit no symptoms themselves.

Is there a treatment or cure?
No. Research and the potential for both a viable treatment and even a cure are promising, but there is currently nothing to stop SMA from progressing.

Why is research so promising?
Although SMA is not commonly known, SMA research is extremely mature and active. Dramatic breakthroughs have been made in the past fifteen years and, as a result of those breakthroughs, SMA has quickly gone from a poorly understood disease to being on the doorstep of a viable treatment. Towards that end, the National Institutes of Health (NIH) has coined SMA as the disease “closest to treatment” of more than 600 neurological disorders, and over 50 of the nation’s leading doctors and scientists, including Nobel Laureate James Watson, signed a statement stressing that with funding of $20 to $30 million annually, an effective therapy for SMA can be achieved in the near term of five years or less.

According to the NIH:

“Spinal Muscular Atrophy was chosen because of the severity of the disease, its relatively high incidence, and the fact that the gene has been identified and the gene product is known, resulting in leads on possible treatments. There is a gap in funding to advance research on SMA, but if progress can be made, it would have implications for other diseases.”

In addition, the SMA translational research approach used by researchers is now considered a viable research “model” with the potential for enormous benefit to millions of people impacted by other diseases, including ALS/Lou Gehrig’s, Alzheimer’s, Parkinson’s, Duchenne Muscular Dystrophy, Fragile X, Tay Sachs Sandhoff, among others. So much is known about SMA and by finding a treatment and cure for it, the pathway to treatments and cures for many other diseases will become infinitely more attainable.

Is there Carrier Screening?
Yes. A simple blood test will determine if you are a carrier of SMA. This can be done prior to pregnancy so you can better assess your options. Both parents must be carriers for the baby to have the active form of SMA. Currently you must request this test from your doctor. Because of a general lack of awareness of the prevalence, including in the medical world, SMA has yet to be offered as a standard test. If you and your partner are carriers, you have several options. Contact the Claire Altman Heine Foundation at http://www.ClaireAltmanHeineFoundation.org for more information.

For more information or to make a donation to help END SMA, please visit http://GwendolynStrongFoundation.org.

Bill and Victoria Strong
by Bill and Victoria Strong, parents of Gwendolyn and founders of The Gwendolyn Strong Foundation


Lynn Squance
Lynn Squance5 years ago

I am one of those that had never heard of SMA. The loss of every child is a tragedy but I am glad that research is going on. With ties to Alzheimer's, Parkinson's, etc, maybe funding can be looked at through President Obama's 'brain mapping' programme. The body is so interconnected.

Amanda R.
Amanda R9 years ago

We're the only species to get SMA right?

I just wanted to say right now, please don't fall for the "Your baby or your dog" trap, and make sure you support reliable, human-based research. Cut out the useless middleman or...animal.

Somebody's gotta say it...

Heather O.
Heather O9 years ago

Thank you so much. After my son died from Hypoplastic Left Heart Syndrome (not detected nor diagnosed until after his death) I participated and in many cases moderated lost of a child message boards and chat rooms.

When I saw your first post, I remembered the three parents, one couple and one divorced mother all who had lost their babies to SMA.

I am so sorry you have to go through this, but I more than commend you making this horrible condition more widely known.


Carol H.
Past Member 9 years ago

I so glad there is a blood test for this decease because that is so important.
Now a days people that get married don't even have to take a blood test for just to make sure that their blood type are compatable if they decide to have children or if either one or the other are carrying any kind of decease if which I think that is stupid in this day and time I just do.
In the old days that is what you had to do by law I wasn't happy about it but it was the law that is the way it should be today.
Sceening is so important for your future children and for each other to make sure your partner is clean of anything he might or she might not know they are carrying.