Spinal muscular atrophy is an autosomal recessive neurodegenerative disease 
characterised by degeneration of spinal cord motor neurons, atrophy of skeletal 
muscles, and generalised weakness. It is caused by homozygous disruption of the 
survival motor neuron 1 (SMN1) gene by deletion, conversion, or mutation. 
Although no medical treatment is available, investigations have elucidated 
possible mechanisms underlying the molecular pathogenesis of the disease. 
Treatment strategies have been developed to use the unique genomic structure of 
the SMN1 gene region. Several candidate treatment agents have been identified 
and are in various stages of development. These and other advances in medical 
technology have changed the standard of care for patients with spinal muscular 
atrophy. In this Seminar, we provide a comprehensive review that integrates 
clinical manifestations, molecular pathogenesis, diagnostic strategy, 
therapeutic development, and evidence from clinical trials.