Spinal muscular atrophies (SMA) result in progressive degeneration of the anterior horn cells. Most patients present in infancy and childhood but later presentations are known. The condition is inexorably progressive and reduces quality and span of life. Survival motor neuron gene abnormalities are most common, but other genetic abnormalities have been recognised. The therapy is largely supportive at this time. Nusinersen, an antisense oligonucleotide, has recently been approved for treatment of SMA.