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CACNA1S gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

CACNA1S gene

The CACNA1S gene provides instructions for creating a calcium channel subunit that is critical for muscle contraction and movement.

Normal Function

The CACNA1S gene provides instructions for making the main piece (subunit) of a structure called a calcium channel. Channels containing the CACNA1S protein are found in muscles used for movement (skeletal muscles). These skeletal muscle calcium channels play a key role in a process called excitation-contraction coupling, by which electrical signals (excitation) trigger muscle tensing (contraction).

Calcium channels made with the CACNA1S subunit are located in the outer membrane of muscle cells, so they can transmit electrical signals from the cell surface to inside the cell. The channels interact with another type of calcium channel called ryanodine receptor 1 (RYR1) channels (produced from the RYR1 gene). RYR1 channels are located in the membrane of a structure inside the cell that stores calcium ions. Signals transmitted by CACNA1S-containing channels turn on (activate) RYR1 channels, which then release calcium ions inside the cells. The resulting increase in calcium ion concentration within muscle cells stimulates muscles to contract, allowing the body to move.

Health Conditions Related to Genetic Changes

Malignant hyperthermia

CACNA1S gene mutations account for a very small percentage of all cases of malignant hyperthermia. Malignant hyperthermia is a severe reaction to particular anesthetic drugs that are often used during surgery and other invasive procedures. The reaction involves a high fever (hyperthermia), a rapid heart rate, muscle rigidity, breakdown of muscle fibers (rhabdomyolysis), and increased acid levels in the blood and other tissues (acidosis). Complications can be life-threatening without prompt treatment. Researchers have identified several mutations in the CACNA1S gene that are associated with an increased risk of this condition. These mutations replace single amino acids in the CACNA1S protein.

Channels made with the altered CACNA1S proteins likely activate the RYR1 channel improperly in response to certain drugs (particularly some anesthetics and a type of muscle relaxant used during surgery). As a result, large amounts of calcium ions are released from storage within muscle cells. An overabundance of calcium ions activates processes that generate heat (leading to increased body temperature) and produce excess acid (leading to acidosis). An increase in calcium ion concentration also causes skeletal muscles to contract abnormally, which leads to muscle rigidity.

Hypokalemic periodic paralysis

At least 11 mutations in the CACNA1S gene have been identified in people with hypokalemic periodic paralysis, a condition that causes episodes of extreme muscle weakness, usually in the arms and legs. CACNA1S gene mutations cause up to 70 percent of all cases of this disorder.

Mutations in the CACNA1S gene change single protein building blocks (amino acids) used to make the CACNA1S protein, which alters the structure and function of calcium channels in skeletal muscle cells. The altered channels open more slowly than usual, reducing the flow of calcium ions into these cells. This disruption in calcium ion transport prevents muscles from contracting normally. It is unclear precisely how these changes lead to episodes of muscle weakness in people with hypokalemic periodic paralysis.

Other Names for This Gene

  • CAC1S_HUMAN
  • CACH1
  • CACN1
  • CACNL1A3
  • calcium channel, voltage-dependent, L type, alpha 1S subunit
  • Cav1.1
  • CCHL1A3
  • DHPR
  • dihydropyridine receptor
  • dihydropyridine-sensitive L-type calcium channel alpha-1 subunit
  • HOKPP
  • HypoKPP
  • hypoPP
  • MHS5
  • Voltage-dependent L-type calcium channel subunit alpha-1S
  • voltage-gated calcium channel subunit alpha Cav1.1

Frequently Asked Questions

Individuals with a CACNA1S gene mutation or a family history of malignant hyperthermia should strictly avoid volatile anesthetic agents such as halothane, isoflurane, sevoflurane, and desflurane, as well as the depolarizing muscle relaxant succinylcholine. Alternative anesthetic techniques, such as total intravenous anesthesia, are safe options.
Not necessarily. A CACNA1S gene mutation indicates an increased genetic predisposition to malignant hyperthermia, but it does not guarantee a reaction. The severity and likelihood of a reaction can vary, and it is often triggered by specific volatile anesthetic gases or the muscle relaxant succinylcholine.
If a malignant hyperthermia reaction occurs, the anesthetic agents must be immediately stopped, and the patient should be hyperventilated with 100% oxygen. The specific antidote medication, dantrolene, must be administered intravenously as quickly as possible. Cooling measures and management of acidosis and electrolyte imbalances are also critical.
Genetic testing for CACNA1S mutations can be performed using a blood sample. If there is a family history of malignant hyperthermia or a previous suspicious reaction, it is important to discuss this with your doctor or an anesthesiologist, who can refer you for appropriate genetic counseling and testing.
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.

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