Spinal muscular atrophy

Spinal muscular atrophy, or SMA, is a genetic disease affecting motor neurons in the spinal cord and the control of muscle movement. It is caused by a mutation of the survival motor neuron gene 1, or SMN1, which affects nerve cells and leads to debilitating muscle function and often fatal muscle weakness.

There are four primary types of SMA based on age of onset and the manifestation of the disease. Type I, also known as Werdnig-Hoffmann disease, 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. This type is also called juvenile SMA or Kugelberg-Welander disease. 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.

In collaboration with Astellas, Cytokinetics is researching and developing a fast skeletal muscle troponin activator (FSTA) for the potential treatment of patients battling SMA.