At birth Generalized muscle weakness, with possible joint deformities resulting from shortening of muscles. Disease progresses very slowly and life span may be shortened. First affects muscles of eyelids and throat. While progression is slow, weakening of throat muscles in time causes swallowing difficulties. Progresses slowly and rarely leads to total incapacity.
Joint deformities are common.
Disease progresses slowly, yet sudden death can result from cardiac complications. Survival rarely exceeds five years after onset. Life span rarely exceeds age 2. Weakness in arms, legs, upper and lower torso, often with skeletal deformities. Disease progresses rapidly.