Spinal muscular atrophy: Leaders in SMA treatment

Your body has more than 600 muscles — each with a critical role to play. Muscles allow you to do everything from walk to breathe. If your muscles become weak, you may find it hard to perform everyday activities. 

Spinal muscular atrophy (SMA) is a genetic condition that causes weakness by damaging the nerves that go to muscles. These nerves are damaged because there is not enough survival motor neuron (SMN) protein to keep them alive. The gene that makes this protein is missing but there is a “copy gene” that makes a small amount of this protein so children can live, though they are still weak. Due to this muscle weakness, individuals with SMA can have difficulty in walking, eating or breathing. Children with SMA have normal brain development and are as smart as other children their age. Children with SMA are able to learn, play, think and interact, building relationships with those around them.

SMA is a genetic condition, caused by a change to a gene called SMN1. This change leads to a damage of nerves that control your muscles. These nerves are called motor neurons. When motor neurons break down, they cannot send signals to your muscles to make muscles move. Without these signals, muscles become weak and get smaller.

Symptoms of SMA 

SMA is something you are born with, but symptoms might not develop right away. People can start becoming weak from SMA in infancy, childhood or even during adult years. The most common presentation can occur in young infants and is the most severe form. Children with this presentation would be described as “floppy” and may miss important developmental milestones such as rolling, sitting or walking when expected. Older infants might be able to roll and sit, but develop weakness that prevents them from standing or walking. Toddlers and young children could start falling more and being unable to walk or run as fast as other children their age.

Because of this range of weakness and symptoms, we used to divide SMA into “types,” with the type 1 SMA being the most severe presentation (an infant who never was able to roll), type 2 SMA describing an infant who could sit at some point but never stand and type 3 SMA patients presenting in early childhood, after being able to stand. We are using this classification less and less, because it does not take into account the effects of early diagnosis and treatment of SMA.

Diagnosing SMA

Diagnosis of SMA is typically made by genetic testing. 

• If you or a member of your family has a known history of a carrier status or other family member diagnosed with SMA, there are testing options that can be discussed before or during pregnancy with a genetic counselor. 

  • Parents can be tested for carrier status. This will determine the need to test children. 

  • Children can be tested during pregnancy if deemed necessary and safe. This typically includes chorionic villus sampling or amniocentesis. As SMA is a treatable condition, determining the status of your child allows for planning and prompt treatment following birth.

• Luckily for us, Wisconsin, is one of 32 states that has added SMA testing to be included as part of the newborn screening panel. This means that 24 hours after birth, whether in a medical institution or other arrangement, a heel prick is completed and tested for this condition through our state testing lab.

Genetic testing also can be arranged for any person if SMA is suspected. 

At UW Health, we can provide the most current treatment options that best suit both your child and your family’s needs. We are happy to discuss all options, experiences and expectations to aid in this determination.

Our SMA specialists see pediatric patients 18-21 years of age at our Pediatric Neurology Clinic at UW Health and at the American Family Children’s Hospital in Madison, after which time they can be transferred to the Adult Neuromuscular specialists at UW Health in Madison.

Piper was just a week old when her parents learned she had SMA. Without treatment, her muscles would weaken. Breathing and eating would become difficult. At three weeks old, Piper was the first child in Wisconsin treated with a new gene therapy for spinal muscular atrophy. Read Piper’s story

An SMA diagnosis can be hard for families to cope with. There are many national SMA resources you can turn to for information and support: