Classification of muscular dystrophies

1. Big picture

Muscular dystrophies are inherited, progressive diseases of skeletal muscle caused by defects in structural or functional muscle proteins. They cause progressive muscle weakness, usually with muscle wasting, sometimes pseudohypertrophy, and often markedly elevated creatine kinase (CK).

The key exam sentence:

Muscular dystrophies are hereditary progressive myopathies; they cause weakness without sensory loss, and are classified mainly by the affected protein, inheritance pattern, age of onset and muscle distribution.

They must be distinguished from:

• myositis: inflammatory, often painful, subacute, treatable with immunosuppression;
• **myasthe