Motor neuron biology and disease: A current perspective on infantile-onset spinal muscular atrophy.

Infantile-onset spinal muscular atrophy (SMA) is a prototypical disease in which to investigate selective neurodegenerative phenotypes. Caused by low levels of the ubiquitously expressed Survival Motor Neuron (SMN) protein, the disease mainly targets the spinal motor neurons. This selective phenotype remains largely unexplained, but has not hindered the development of SMN repletion as a means to a treatment. Here we chronicle recent advances in the area of SMA biology. We provide a brief background to the disease, highlight major advances that have shaped our current understanding of SMA, trace efforts to treat the condition, discuss the outcome of two promising new therapies and conclude by considering contemporary as well as new challenges stemming from recent successes within the field.