However the conclusive test to distinguish BMD and LGMD is the examination of dystrophin on the muscle biopsy specimen. DMD is fairly predictable. There is a range of severity, and disability progresses more rapidly in some people than in others. Nevertheless the range of severity is rather narrow. BMD is much more variable.
Some affected people are able to walk only until early adulthood, others to an advanced age.
Survival in some is to middle age but others have survived more than 80 years. Some develop heart trouble in early adulthood, others never do. There are sometimes big differences in severity of BMD, between affected individuals in the same family. The process is like that described for DMD but the doctor's findings are in all respects generally less severe. The SCK level is also increased, the EMG and muscle biopsy show changes consistent with the diagnosis of a dystrophy.