Jim Willson, a patient with spinal muscular atrophy (SMA), discusses his diagnostic journey.

Mr. Willson talks about what it was like growing up in the ’70s, when little was known about SMA and before he knew what he had. He also talks about what it has been like since his diagnosis as treatments have become available. Mr. Willson is currently in a clinical trial for risdiplam.

SMA is a genetic disease that affects motor neurons in the spinal cord and control of muscle movement. It is caused by a mutation in the survival motor neuron gene 1 (SMN1) which affects nerve cells and leads to loss of muscle function.

There are four primary types of SMA based on age of onset and the manifestation of the disease. Type I is the most common and severe type of SMA. Type II, diagnosed in children between the ages of 6 months and 2 years, results in a delay or failure to reach motor milestones. Children with Type III, usually diagnosed before age 3 and sometimes as late as their teenage years, learn to walk but have mobility problems as they grow. Type IV is rare, with symptoms usually beginning after age 35. Other forms of SMA that are caused by mutations in genes other than SMN1 are spinal muscular atrophy respiratory distress (SMARD), distal SMA, and Kennedy’s disease.

For more information about SMA and other rare neuromuscular disorders, visit checkrare.com/diseases/musculoskeletal-diseases