title: Spinal muscular atrophy: clinical classification and disease heterogeneity.
abstract: The clinical classification of spinal muscular atrophy, caused by deletion of the survival motor neuron 1 gene (SMN1), is based on age at onset and maximum function achieved. Evidence suggests that maximum function achieved is more closely related to life expectancy than age at onset. Therefore, it is important to wait for a period before assigning a patient to 1 of 5 classes of the disorder. Several diseases result from degeneration of the anterior horn cell but are not caused by SMN1. The classification for these conditions is evolving. This article offers an attempt at organizing one's thinking about this disease group.
authors.affiliation: Department of Neurology, Oregon Health and Science University, Shriners Hospital for Children-Portland, Portland, Oregon, USA. russmanb@ohsu.edu
authors.forename: Barry S
authors.initials: BS
authors.lastname: Russman
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D002648:Child; D002675:Child, Preschool; D002895:Chromosomes, Human, Pair 5 / Q000235:genetics; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics*; D003937:Diagnosis, Differential; D018450:Disease Progression; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008017:Life Expectancy; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D009134:Muscular Atrophy, Spinal / Q000145:classification* / Q000175:diagnosis* / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics*; D055532:SMN Complex Proteins; D055533:Survival of Motor Neuron 1 Protein
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D009419:Nerve Tissue Proteins; D016601:RNA-Binding Proteins; D055532:SMN Complex Proteins; C526471:SMN1 protein, human; D055533:Survival of Motor Neuron 1 Protein