label: spinal muscular atrophy, type III
label_lc: spinal muscular atrophy, type iii
description: Proximal spinal muscular atrophy type 3 (SMA3) is a relatively mild form of proximal spinal muscular atrophy characterized by muscle weakness and hypotonia resulting from the degeneration and loss of the lower motor neurons in the spinal cord and the brain stem nuclei.