Myotonia congenita is a rare genetic disease that affects chloride channels and cause transient stiffness in the muscles. It has two sub types according to the genetic phenotyping. 1. Thomson disease 2. Becker's disease Becker's disease is an autosomal recessive sub type that affects more commonly leg muscles and the onset of symptoms manifest slightly in older age. We are reporting a case of Becker disease in 16 years old boy having delayed relaxation of muscles noticing his symptoms for the last 8 years.
