A study suggests that spinal muscular atrophy (SMA), a genetic neuromuscular disease in infants and children, results primarily from motor circuit dysfunction, not motor neuron or muscle cell dysfunction, as is commonly thought. In a second study, the researchers identified the molecular pathway in SMA that leads to problems with motor function. Findings from the studies, conducted in fruit fly, zebrafish and mouse models of SMA, could lead to therapies for this debilitating and often fatal neuromuscular disease.