Types of Muscular Dystrophy and Neuromuscular Diseases

What are the types of Muscular Dystrophy?
Muscular dystrophy is a group of inherited diseases that are characterized by weakness and wasting away of muscle tissue, with or without the breakdown of nerve tissue. There are nine types of muscular dystrophy, but in each type there is an eventual loss of strength, increasing disability, and possible deformity.

The most well known of the muscular dystrophies is Duchenne muscular dystrophy (DMD), followed by Becker muscular dystrophy (BMD). They cause similar patterns of weakness and disability and are inherited in the same way, although weakness and disability are more severe in DMD. Becker dystrophy is often classified as a less severe form of Duchenne dystrophy. They both are due to defects of the same gene, the normal function of which is to enable muscle fibers to make a particular chemical substance, a protein called dystrophin. Muscle fibers in people affected with DMD are extremely deficient in dystrophin, but in BMD the deficiency is less severe.

Listed below are the nine different types of muscular dystrophy. Each type differs in the muscles affected, the age of onset, and its rate of progress.

Becker - age at onset: two to 16 years; symptoms are almost identical to Duchenne but less severe; progresses more slowly than Duchenne; survival into middle age.

Congenital - age at onset: birth; symptoms include general muscle weakness and possible joint deformities; disease progresses slowly; shortened life span.

Duchenne - age at onset: two to six years; symptoms include general muscle weakness and wasting; affects pelvis, upper arms, and upper legs; eventually involves all voluntary muscles; survival beyond 20s is rare.

Distal - age at onset: 40 to 60 years; symptoms include weakness and wasting of muscles of the hands, forearms, and lower legs; progress is slow; rarely leads to total incapacity.

Emery-Dreifuss - age at onset: childhood to early teens; symptoms include weakness and wasting of shoulder, upper arm, and shin muscles; joint deformities are common; progress is slow; sudden death may occur from cardiac problems.

Facioscapulohumeral - age at onset: teens to early adults; symptoms include facial muscle weakness and weakness with some wasting of shoulders and upper arms; progress is slow, with periods of rapid deterioration; life span may be many decades after onset.

Limb-Girdle - age at onset: late childhood to middle age; symptoms include weakness and wasting, affecting shoulder girdle and pelvic girdle first; progress is slow; death is usually due to cardiopulmonary complications.

Myotonic - age at onset: 20 to 40 years; symptoms include weakness of all muscle groups accompanied by delayed relaxation of muscles after contraction; affects face, feet, hands, and neck first; progress is slow, sometimes spanning 50 to 60 years.

Oculopharyngeal - age at onset: 40 to 70 years; symptoms affect muscles of eyelids and throat causing weakening of throat muscles, which in time causes inability to swallow and emaciation from lack of food; progress is slow.

What are other neuromuscular diseases?