myotonia congenita; Thomsen disease; Becker disease; myotonia levior

Pathology

• skeletal muscle stiffness (delayed relaxation), due to membrane hyperexcitability

Genetics

• autosomal dominant (Thomsen disease)
• autosomal recessive (Becker disease)
• associated with defects in CLCN1

Clinical manifestations

• muscle rigidity

Notes

• a variant form of Thomsen disease is myotonia levior that is characterized by milder symptoms, later onset & absence of muscle hypotrophy & hypertrophy

More general terms

• myotonic disorder
• genetic disease of muscle (inherited myopathy)

Database

• OMIM: https://mirror.omim.org/entry/160800
• OMIM: https://mirror.omim.org/entry/255700