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SCN4A gene

Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

SCN4A gene

The SCN4A gene provides instructions for sodium channels in skeletal muscles, with mutations leading to various muscle-related disorders characterized by weakness or stiffness.

Normal Function

The SCN4A gene belongs to a family of genes that provide instructions for making sodium channels. These channels, which transport positively charged sodium ions into cells, play a key role in a cell's ability to generate and transmit electrical signals.

The SCN4A gene provides instructions for making a critical part (the alpha subunit) of sodium channels that are abundant in skeletal muscles. These channels control the flow of sodium ions into muscle cells, which triggers the contractions necessary for movement.

Health Conditions Related to Genetic Changes

Hyperkalemic periodic paralysis

Variants in the SCN4A gene cause episodes of extreme muscle weakness often associated with high levels of potassium in the blood. These variants delay the closing of sodium channels, causing an abnormal influx of sodium ions that triggers the release of potassium from muscle cells, reducing the ability of muscles to contract.

Hypokalemic periodic paralysis

Variants in the SCN4A gene account for about 10 percent of cases of this condition, which causes episodes of extreme muscle weakness associated with low levels of potassium in the blood. The abnormal channels prevent muscles from contracting normally, leading to long-lasting episodes of severe weakness.

Paramyotonia congenita

This muscle disease is characterized by episodes of sustained muscle tensing (myotonia) that prevent muscles from relaxing. Variants cause sodium channels to open too quickly or stay open too long, increasing sodium influx and triggering prolonged muscle contractions. Symptoms can be triggered by cold temperatures.

Potassium-aggravated myotonia

This condition causes episodes of muscle stiffness that may be triggered by eating potassium-rich foods. The variants delay the closing of sodium channels, and the presence of excess potassium causes further sodium influx, leading to prolonged muscle contractions.

Other Names for This Gene

  • Na(V)1.4
  • Nav1.4
  • SCN4A_HUMAN
  • skeletal muscle voltage-dependent sodium channel type IV alpha subunit
  • SkM1
  • sodium channel, voltage gated, type IV alpha subunit
  • sodium channel, voltage-gated, type IV, alpha
  • sodium channel, voltage-gated, type IV, alpha subunit
  • voltage-gated sodium channel type 4 alpha

Frequently Asked Questions

Patients with potassium-aggravated myotonia should strictly limit high-potassium foods to prevent muscle stiffness episodes. Common triggers include bananas, oranges, potatoes, tomatoes, avocados, spinach, and dried fruits. It is also advisable to avoid sports drinks and energy bars that are fortified with electrolytes, as these can contain significant amounts of potassium. Keeping a detailed food diary can help identify personal thresholds and specific items that provoke symptoms.
Cold temperatures are a primary trigger for paramyotonia congenita, causing muscles to stiffen and making movement difficult, a phenomenon often called "cold paresis." To manage this, patients should dress in layers to maintain core body temperature, wear gloves and hats in cold environments, and allow time to warm up before physical activity. Avoiding sudden exposure to cold air or water is crucial, and some patients find that using a heating pad or warm compresses on affected muscles before movement helps reduce stiffness.
Most SCN4A-related conditions, including hyperkalemic and hypokalemic periodic paralysis, paramyotonia congenita, and potassium-aggravated myotonia, follow an autosomal dominant inheritance pattern. This means that a person with the condition has a 50 percent chance of passing the genetic variant to each of their children. However, some cases arise from new (de novo) mutations with no family history. Genetic counseling is recommended to discuss specific family risks and testing options for relatives.
While many episodes of periodic paralysis resolve on their own, certain signs require immediate medical attention. These include difficulty breathing, swallowing, or speaking, which may indicate that the weakness has affected the diaphragm or throat muscles. Additionally, if an episode lasts longer than 24 to 48 hours, or if the patient experiences chest pain or palpitations, they should seek emergency care. These symptoms can indicate severe electrolyte imbalances or cardiac involvement that requires urgent intervention.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.