National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Potassium aggravated myotonia



Other Names:
Myotonia fluctuans; Myotonia permanens; Myotonia congenita, atypical; Myotonia fluctuans; Myotonia permanens; Myotonia congenita, atypical; Myotonia congenita, acetazolamide-responsive See More
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Potassium aggravated myotonia is a group of diseases that causes tensing and stiffness (myotonia) of skeletal muscles, which are the muscles used for movement.  The three types of potassium-aggravated myotonia include myotonia fluctuans, myotonia permanens, and acetazolamide-sensitive myotonia.[1]  Potassium aggravated myotonia is different from other types of myotonia because symptoms get worse when an affected individual eats food that is rich in potassium.  Symptoms usually develop during childhood and vary, ranging from infrequent mild episodes to long periods of severe disease.[1][2]  Potassium aggravated myotonia is an inherited condition that is caused by changes (mutations) in the SCN4A gene.[2]  Treatment begins with avoiding foods that contain large amounts of potassium; other treatments may include physical therapy (stretching or massages to help relax muscles) or certain medications (such as mexiletine, carbamazapine, or acetazolamide).[1]
Last updated: 4/17/2012

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.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Hypertonia 0001276
Myotonia 0002486
30%-79% of people have these symptoms
Elevated serum creatine kinase
Elevated blood creatine phosphokinase
Elevated creatine kinase
Elevated circulating creatine phosphokinase
Increased CPK
High serum creatine kinase
Elevated serum creatine phosphokinase
Elevated serum CPK
Increased serum creatine phosphokinase
Increased serum creatine kinase
Increased serum CK
Increased creatine phosphokinase
Increased creatine kinase
[ more ]
0003236
EMG abnormality 0003457
Feeding difficulties in infancy 0008872
Flexion contracture
Flexed joint that cannot be straightened
0001371
Gait disturbance
Abnormal gait
Abnormal walk
Impaired gait
[ more ]
0001288
Myalgia
Muscle ache
Muscle pain
[ more ]
0003326
5%-29% of people have these symptoms
Asthma 0002099
Chest pain 0100749
Hyperkalemia
Elevated serum potassium levels
0002153
Joint stiffness
Stiff joint
Stiff joints
[ more ]
0001387
Muscle spasm 0003394
Muscle weakness
Muscular weakness
0001324
Ophthalmoparesis
Weakness of muscles controlling eye movement
0000597
Respiratory insufficiency
Respiratory impairment
0002093
Skeletal muscle hypertrophy
Increased skeletal muscle cells
0003712
Percent of people who have these symptoms is not available through HPO
Apneic episodes in infancy 0005949
Autosomal dominant inheritance 0000006
Laryngospasm 0025425
Muscle stiffness 0003552
Stridor 0010307
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Last updated: 7/1/2020

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources


Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.

Conditions with similar signs and symptoms from Orphanet
Differential diagnoses include myotonia congenita (see this term), and cold sensitive myotonias such as paramyotonia congenita and hyperkalemic periodic paralysis with paramyotonia (see these terms).
Visit the Orphanet disease page for more information.

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

  • Genetics Home Reference (GHR) contains information on Potassium aggravated myotonia. This website is maintained by the National Library of Medicine.

In-Depth Information

  • 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 Potassium aggravated myotonia. Click on the link to view a sample search on this topic.

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  • How many people in the world have potassium aggravated myotonia? See answer