Congenital myotonia is a rare genetic condition that affects muscle function. It is characterized by prolonged muscle stiffness, especially after periods of rest or inactivity. This stiffness can make it difficult for individuals to relax their muscles, leading to challenges in movement. The condition is caused by mutations in specific genes, such as the CLCN1 gene, which is responsible for muscle chloride channels. Symptoms often appear in infancy or early childhood and can vary in severity. While there is no cure, management strategies, including physical therapy and medications, can help improve muscle function and quality of life.