|Definition||A childhood spinal muscular atrophy that is a severe form and is characterized by muscle weakness onset from birth to six months of age, the inability to sit unassisted.
hereditary motor neuropathy proximal type I [EXACT]
HMN (Hereditary motor Neuropathy) Proximal type I [EXACT]
infantile muscular atrophy [EXACT]
progressive muscular atrophy of infancy [EXACT]
Spinal muscular atrophy 1 [EXACT]