What is Spinal Muscular Atrophy?

By Carol Muse Evans

In Alabama, an estimated five babies are born with Spinal Muscular Atrophy (SMA) every year. In 2021, there were approximately 183 people living with SMA in Alabama, according to Cure SMA, an organization that provides resources for the SMA community.

SMA is a genetic disease affecting the central nervous system, peripheral nervous system and voluntary muscle movement (skeletal muscular), according to The Muscular Dystrophy Association (MDA). The primary effect is on the muscles, and it is classified as a “motor neuron disease,” according to the MDA.

Symptoms of SMA can range from mild to severe, according to Karen Chen of the Spinal Muscular Atrophy (SMA) Foundation. “In the past, a doctor may suspect SMA when a child was noticeably weak or had a delay in achieving development milestones, such as ability to hold their heads up, sitting independently, standing or walking. If SMA was suspected, the doctor would typically refer the child to a neurologist and order a genetic test (via blood sample) to identify defects in the SMN1 gene in order to confirm the diagnosis,” Chen explains.

Those symptoms tend to impact the ability to walk, stand, sit, swallow and/or eventually move. “SMA patients often develop respiratory illnesses, and bone and/or spial deformities which may require surgical treatment,” Chen adds.

For Alabama mom Logan Nantz, her two-year-old Hayden’s diagnosis almost came without them having time to actually see symptoms. “Hayden was 6 days old when our pediatrician woke us from our sleep early in the morning and called us into her office to deliver the news,” Nantz recalls.

For Hayden, the physical limitations aren’t always visible, so Nantz says it can be hard to explain to others who may be around or helping care for her…So sometimes we have to elect to not do things or participate as we maybe would,” Nantz says.

For Tyesha Jefferson of Birmingham, it has been a totally different story. She wasn’t diagnosed until around age 28, she says. This Birmingham mom says that SMA causes difficulty with basic life functions such as breathing, swallowing and walking.

SMA affects approximately 1 in 11,000 births in the U.S., and about one in every 50 Americans is a carrier for SMA, according to the Foundation. Carriers may not exhibit symptoms, but could pass it along to children.

Her symptoms showed up in adulthood, but now 15 years later, Jefferson says she maintains her strength through physical therapy three times a week, working out four times a week and through an at-home treatment, Evrysdi.

Jefferson and her 10-year-old daughter are happy to share their experiences and offer advice for other parents and kids about how to navigate having a mom with a disability.

Brooklyn Nichols was diagnosed when she wasn’t hitting her “milestones” around 5 to 6 months old, her mom Keanna Nichols says. “If you would attempt to stand her [Brooklyn] on your legs, her legs would go down like wet noodles,” she says. At first there wasn’t a large concern from the pediatrician, but a few months later there was, and she was referred to a neurologist who still sees Brooklyn, now 11 years old.

SMA is an autosomal recessive genetic condition, according to Cure SMA, www.curesma.org. What does this mean exactly? For a child to have SMA, they must inherit two non-working copies of the SMN1 gene – typically one from each parent. People can be “carriers” of SMA, so if only one parent is a carrier, the child is usually not at risk for SMA, though the child does have a 50 percent chance of being a carrier themselves. According to Cure SMA, a DNA test is the only way to know if a person is a carrier, a simple blood or saliva test that can detect about 95 percent of carriers.

The American College of Obstetricians and Gynecologists (ACOG) recommends that all women are thinking about becoming pregnant or who are already pregnant be offered carrier screening for SMA and other genetic conditions. If there is a family history of SMA, carrier screening is high recommended.

What is the prognosis for those diagnosed?

Chen says it varies based on the type of SMA a patient has, and the timing of the treatment. Without treatment, the most severe form of SMA (Type 1) is often fatal before age two, whereas children with more moderate forms of SMA (Type 2 and 3) typically live into adulthood and can have a normal life expectancy, depending on the severity of the respiratory, nutrition and orthopedic symptoms. “However, with the recent approval of SMA therapies, the prognosis is treatment improved,” Chen points out, “even in the most several form of the disease when patients are treated presymptomatically or early in their disease course.”

What are the current treatments?

Chen says there are three FDA- approved treatments in the U.S. All three target the genetic cause of the disease by increasing SMN levels and have shown to be effective in clinic trials. Spinraza is approved for children and adults with SMA. Zolgensma is a one-time SMN gene replacement therapy delivered through IV and approved for patients under age two. Evrysdi is a small molecule delivered orally daily that targets splicing of SMN2 to increase SMN levels, and it is approved for children and adults.

When Brooklyn was diagnosed, her mom says there were no treatments available and they were told she likely would not live beyond age 3. But medicine has progressed! “The key is early intervention, and not being afraid of being an advocate for your child, especially concerning their medical care and education,” Nicols says. Brooklyn now takes Evrysdi, the only at-home treatment for SMA.

“We have lived on the edge of the ‘rules’ with this diagnosis, and I’m so proud of what Hayden has shown us she is capable of, because we didn’t put her in a box…the past couple of years have taught us to live in the present, much more than we ever knew how before our daughter was born,” Nantz adds.

FOR MORE INFORMATION:

» www.curesma.org

» www.mda.org/disease/spinal-muscular-atrophy