How an SMA diagnosis resolved years of unanswered questions

Marci lived decades before discovering she had spinal muscular atrophy (SMA), a rare neuromuscular disease – her doctor diagnosed her at age 51. Before that, she had simply assumed that the physical challenges she faced were a normal part of life due to clumsiness, age or a prior injury. 

"I'd seen signs of weakness, but I ignored them or blamed them on something else," she says. "A friend of mine noticed that I had difficulty getting out of chairs and walking up steps was very labored for me. I thought it was due to when I broke my leg in my 30s."

Because of her friend's concern, Marci visited an orthopedic surgeon who referred her to a neurologist, which led to her SMA diagnosis.

Understanding the broad spectrum of SMA

SMA is a genetic, neuromuscular disorder characterized by a loss of motor neurons in the spinal cord and lower brain stem.

While some people with the disease may show significant symptoms, those with other forms may overlook theirs or attribute them to something else. A story like Marci’s illustrates the broad spectrum of the disease.

SMA is caused by a deficiency of the survival motor neuron (SMN) protein. Without sufficient SMN protein, the signals between motor neurons and muscles are disrupted, resulting in muscle atrophy and weakness. Though symptoms of infantile-onset SMA are often more acute, the disorder impacts people of all ages.1 Each person’s experience living with SMA can vary – some people may never sit, some sit but never walk and some walk but may lose that ability over time. What can be consistent for many people with SMA is life-altering progressive muscle weakness, motor functional impairment and disability.1, 2

"The doctor explained that my father and my mother were carriers of this gene, and that's how it manifested," she says. "It was shocking to me because my siblings don't exhibit any of the weaknesses that I have."

"Severity of disease can vary significantly across different ages and progresses over time. In some young patients, it often presents shortly after they are born, struggling to move, breathe and feed. Others develop relatively normally but then start to have trouble walking around the ages of six or seven3", says Maha Radhakrishnan, M.D., Chief Medical Officer at Biogen. "Some can have normal childhoods, participating in sports, for example, and only start noticing subtle loss in their ability to do things in their late teens, 20s, or 30s, thus receiving a diagnosis later in life.3"

Maha Radhakrishnan, M.D.
Chief Medical Officer at Biogen.

Unfortunately, later diagnosis presents another challenge due to the degenerative nature of the disease. Once motor neurons are gone, the loss is irreversible. As time passes and the disease progresses, many patients need physical therapy and may lose the ability to stand or walk, requiring the use of a wheelchair.4 Prompt diagnosis and early intervention is critical to be able to prevent further motor neuron loss and early treatment can potentially lead to better outcomes for patients.5, 6

Marci's story

Once Marci was diagnosed with SMA, it explained much about her medical history, dating back to her childhood. "You take a walk down memory lane," she says. "I had weak areas in my muscles, but when I was 11 years old, they didn't know what SMA was." Her doctor at the time determined that she was simply growing too fast.

In retrospect, this was just the beginning. Over the years, she'd broken her leg, arm, femur and humerus bones. "Having all these bones break was very unusual," she says. "When I fall, it's like I don't have any shocks in my legs. I can't catch myself."

The reason behind the challenges Marci faced with activities like horseback riding, skiing and tennis now became clear. "I didn't realize back then what was going on with me," she says.

The diagnosis has also helped Marci understand some less obvious aspects of her life. "I used to trip and fall a lot, but I didn't know why until I got this diagnosis," she says, recalling how that impacted her travel experiences. But she has learned to adapt.

"When I'm walking in a new city, I can sometimes miss the beautiful architecture and buildings because I'm always looking at the ground so I don't trip. Now I make sure to stop a lot, look around at my surroundings and try to appreciate them."

Hope for the future

Thirty-six states in the U.S. now screen newborn babies for SMA, comprising 71% of all infants, and newborn screening programs are being introduced in countries around the world.6 Better understanding and awareness of SMA7 are also leading to earlier diagnosis and treatment for older patients to help preserve and potentially improve motor function. Importantly, SMA therapies introduced in recent years have forever shifted the natural history of the disease, giving the SMA community new hope.

For Marci, it’s about clarity and a path forward. "I’m the type of person that wants answers, and I felt that the journey and all of the different doctors I visited to get this answer meant that now I could press on with my life armed with this information.”

  1. National Institute of Neurological Disorders and Stroke, NIH. Spinal Muscular Atrophy Fact Sheet. Available at Accessed April 2021.
  2. Wadman RI, Wijngaarde CA, Stam M, et al. Muscle strength and motor function throughout life in a cross-sectional cohort of 180 patients with spinal muscular atrophy types 1c–4. Eur J Neurol. 2018;25(3):512-518.
  3. Together in SMA. Signs & Symptoms. Available at Accessed April 2021.
  4. Muscular Dystrophy Association. Types of Spinal Muscular Atrophy. Available at Accessed April 2021.
  5. De Vivo DC, Bertini E, Swoboda KJ, et al. Nusinersen initiated in infants during the presymptomatic stage of spinal muscular atrophy: Interim efficacy and safety results from the Phase 2 NURTURE study. Neuromuscul Disord. 2019;29(11):842-856.
  6. Cure SMA. Newborn Screening for SMA. Available at Accessed April 2021.
  7. SpineUniverse. Adult Spinal Muscular Atrophy: Symptoms. Available at Accessed April 2021.

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