Definition - one of a group of diseases that cause problems with the tone and contraction of skeletal muscles; there are two types, Becker’s disease and Thomsen’s disease; Becker’s is the more common form

Cause - mutations in a gene that carries instructions for a chloride channel, a pore in the muscle cell surface that regulates the movement of chloride molecules

Onset - early to late childhood

Symptoms - delayed muscle relaxation and muscle stiffness, typically provoked by sudden movements after rest

Progression - does not progress

Inheritance - Becker: autosomal recessive, or produced by defective genes contributed by both parents; Thomsen: autosomal dominant, or produced by a defective gene contributed by one parent

Facts About Myopathies