Myotonia Congenita (Thomsen Disease and Becker Type)

Signs and Symptoms

Symptoms of the disease can vary from person to person and people with the same disease may not have the same symptoms. In Myotonia Congenita there are two modes of inheritance: Becker disease (BD), autosomal recessive, and Thomsen disease (TD), autosomal dominant (See Causes/Inheritance). BD usually appears later in childhood and causes more severe muscle stiffness in males more than females. Enlargement of muscle fibers are more prominent in individuals with BD than TD. People with BD often experience temporary attacks of muscle weakness, particularly in the arms and hands, brought on by movement after periods of rest. They may also develop mild, permanent muscle weakness over time. This muscle weakness is not seen in people with TD. TD has an earlier onset with milder symptom compared to BD.