NCIthesaurus has symptom existence starts during childhood spinal muscular atrophy juvenile spinal muscular atrophy DOID:13161 DOID:12376 NCI:C118847 ICD9CM:335.11 UMLS_CUI:C0152109 SNOMEDCT_US_2025_09_01:54280009 disease_ontology MIM:253400 MESH:D014897 A childhood spinal muscular atrophy that has age of onset after 18 months and is characterized by muscle weakness after early childhood and the ability to stand and walk and that has_material_basis_in homozygous or compound heterozygous mutation in the SMN1 gene on chromosome 5q13. Kugelberg-Welander disease OMIM mapping confirmed by DO. [SN]. SMA3 Spinal Muscular Atrophy Type 3 Type III Spinal Muscular Atrophy Young adult onset muscle weakness