Myotonia congenita is a genetic disorder that affects muscle relaxation after contraction. Individuals with this condition experience stiffness and difficulty in relaxing their muscles, particularly after physical activity. This can lead to challenges in movement and may cause discomfort. The condition is caused by mutations in the CLCN1 gene, which is responsible for the function of chloride channels in muscle cells. Myotonia congenita is often inherited in an autosomal dominant or autosomal recessive manner, and symptoms can vary in severity. Treatment focuses on managing symptoms and improving muscle function.