Catalog
Adult onset spinal muscular atrophy, Type IV
Link to WHO Definition
Adult onset spinal muscular atrophy, Type IV – http://id.who.int/icd/entity/443229384
In SMA type 4 weakness, most commonly develops after 35 years of age (less commonly between 18 to 35 years old). Weakness of proximal muscles is more prominent in the legs than in the arms. Insidious onset and very slow progression are the characteristic features, and life span is normal.