MONDO_0009673 (spinal muscular atrophy, type II) can be described as follows. Proximal spinal muscular atrophy type 2 (SMA2) is a chronic infantile 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. Also known as: Intermediate spinal muscular atrophy, SMA type 2, SMA type II, SMA-II, SMA2, chronic infantile spinal muscular atrophy, chronic spinal muscular atrophy, muscular atrophy, spinal, infantile chronic form.