Disease at a Glance

Summary
Hyperkalemic periodic paralysis is a genetic disease that causes episodes of extreme muscle weakness and an increase of the potassium levels in the blood. Muscle weakness during an attack usually affects the arms and legs and muscles of the eyes, throat, and trunk. Most often, these episodes involve a temporary inability to move muscles in the arms and legs. Normally an episode lasts for 15 minutes to an hour, but in some people the episodes may last a few days to a week. Factors that can trigger attacks include rest after strenuous exercise, potassium-rich foods, stress, fatigue, and exposure to cold. Depolarizing anesthetics should also be avoided. Muscle strength usually returns to normal between episodes, although many people continue to experience mild stiffness, particularly in muscles of the face and hands. Some affected individuals may develop permanent muscle weakness and a chronic progressive myopathy. Hyperkalemic periodic paralysis is caused by genetic changes in the SCN4A gene and is inherited in an autosomal dominant manner. Diagnosis is based on clinical symptoms including the increase of blood potassium level during an episode but normal levels of blood potassium level in between episodes. Genetic testing can confirm the diagnosis.
Estimated Number of People with this Disease
In the U.S., this disease is estimated to be fewer than

5,000

What Information Does GARD Have For This Disease?

Many rare diseases have limited information. Currently GARD is able to provide the following information for this disease:

*Data may be currently unavailable to GARD at this time.
When do symptoms of this disease begin?
The most common ages for symptoms of a disease to begin is called age of onset. Age of onset can vary for different diseases and may be used by a doctor to determine the diagnosis. For some diseases, symptoms may begin in a single age range or several age ranges. For other diseases, symptoms may begin any time during a person's life.
Prenatal
Before Birth
Newborn
Birth-4 weeks
Infant
1-23 months
Child Selected
2-11 years
Adolescent
12-18 years
Adult
19-65 years
Older Adult
65+ years
The common ages for symptoms to begin in this disease are shown above by the colored icon(s).

Symptoms

These symptoms may be different from person to person. Some people may have more symptoms than others and symptoms can range from mild to severe. This list does not include every symptom.
This disease might cause these symptoms:
Nervous System

21 Symptoms

Tile View
List View
Tile View
List View

Nervous System

The nervous system is made up of the brain, spinal cord, and nerves. Common symptoms of problems in the nervous system include trouble moving, speaking, swallowing, breathing, or learning. Problems with memory, senses, or mood may also occur. Nervous system diseases are usually diagnosed and treated by neurologists.

Causes

Genetic Disease

Hyperkalemic periodic paralysis is a genetic disease, which means that it is caused by one or more genes not working correctly.

Disease causing variants in the following gene(s) are known to cause this disease: SCN4A

Questions:

Inheritance

All individuals inherit two copies of most genes. The number of copies of a gene that need to have a disease-causing variant affects the way a disease is inherited. This disease is inherited in the following pattern(s):

Questions:

Last Updated: Nov. 8, 2021