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Disease Profile

Paramyotonia congenita

Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.


US Estimated

Europe Estimated

Age of onset





Autosomal dominant A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease.


Autosomal recessive Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype.


dominant X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.


recessive Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder.


Mitochondrial or multigenic Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.

Multigenic or multifactor Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.


Not applicable


Other names (AKA)

PMC; Paramyotonia congenita of Von Eulenburg; Paralysis periodica paramyotonica;


Congenital and Genetic Diseases; Musculoskeletal Diseases; Nervous System Diseases


Paramyotonia congenita is an inherited condition that affects muscles used for movement (skeletal muscles), mainly in the face, neck, arms, and hands. Symptoms begin in infancy or early childhood and include episodes of sustained muscle tensing (myotonia) that prevent muscles from relaxing normally and lead to muscle weakness. Symptoms in paramyotonia congenita worsen during exposure to cold temperatures, and unlike many other forms of myotonia, worsen with exercise and repeated movements. This condition is caused by mutations in the SCN4A gene and is inherited in an autosomal dominant pattern.[1]


This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Medical Terms Other Names
Learn More:
30%-79% of people have these symptoms
Cold paresis
Cold-sensitive myotonia
Poor swallowing
Swallowing difficulties
Swallowing difficulty

[ more ]

Facial muscle hypertrophy
Increased size of facial muscles
Large facial muscles

[ more ]

Feeding difficulties
Feeding problems
Poor feeding

[ more ]

Handgrip myotonia
Muscle stiffness
Muscle ache
Muscle pain

[ more ]

Myotonia of the face
Myotonia of the jaw
Myotonia of the upper limb
Neonatal hypotonia
Low muscle tone, in neonatal onset
Neonatal inspiratory stridor
Paradoxical myotonia
Percussion myotonia
5%-29% of people have these symptoms
Abnormal blood potassium concentration
EMG: myopathic abnormalities
Periodic hypokalemic paresis
Percent of people who have these symptoms is not available through HPO
Autosomal dominant inheritance
Infantile onset
Onset in first year of life
Onset in infancy

[ more ]

Inspiratory stridor
Muscle weakness
Muscular weakness
Skeletal muscle hypertrophy
Increased skeletal muscle cells


Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

    Organizations Providing General Support

      Learn more

      These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

      Where to Start

        In-Depth Information

        • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
        • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
        • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
        • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
        • PubMed is a searchable database of medical literature and lists journal articles that discuss Paramyotonia congenita. Click on the link to view a sample search on this topic.


          1. Paramyotonia congenita. Genetics Home Reference. April 2007 ; https://ghr.nlm.nih.gov/condition/paramyotonia-congenita. Accessed 11/17/2011.