Muscle weakness affects hands and legs and may involve impairment of sensation. Severity and progression vary. Intense exercise can cause muscle destruction and possible damage to kidneys. Reducing strenuous exercise can lessen severity. For infants, disease is generalized and severe with heart, liver and tongue enlargement common.
Adult form involves weakness of mid-body and respiratory muscles.
Disease varies widely in severity and progression. Some patients do not experience muscular weakness until late teens or early adulthood. Brain is often involved, with seizures, deafness, loss of balance and vision, and retardation common. Progression and severity vary. Varied weakness of shoulder, hip, face and neck muscles.