Congenital Myasthenic Syndromes
Congenital myasthenic syndromes (CMS) are a group of genetic conditions that all include muscle weakness that gets worse with physical activity. There are many subtypes of CMS with different symptoms, severity, and treatments. Most people with CMS develop symptoms in infancy or by early childhood, but the age at which symptoms begin can vary. Symptoms range from mild to severe muscle weakness and may get worse over time or only occur periodically. The muscles of the face, neck, throat, eyes and limbs are most affected. There are at least 32 genes associated with CMS. Most are inherited in an autosomal recessive pattern. Genetic testing is necessary to tell the difference between subtypes. Treatment is based on managing the symptoms, and may differ depending on the subtype. The long-term outlook is not well understood and differs greatly from person to person.