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CASQ2 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

CASQ2 gene

The CASQ2 gene provides instructions for making the protein calsequestrin 2, which is essential for regulating calcium ion flow and maintaining a regular heart rhythm.

Normal Function

The CASQ2 gene provides instructions for making a protein called calsequestrin 2. This protein is found in heart (cardiac) muscle cells called myocytes, where it is involved in the storage and transport of positively charged calcium atoms (calcium ions).

Within myocytes, calsequestrin 2 is located in a cell structure called the sarcoplasmic reticulum, which acts as a storage center for calcium ions. Most of these ions are stored by binding to calsequestrin 2. This protein also helps regulate a protein called the RYR2 channel, which controls the flow of calcium ions out of the sarcoplasmic reticulum.

For the heart to beat normally, the cardiac muscle must tense (contract) and relax in a coordinated way. This cycle results from the precise control of calcium ions within myocytes. In response to signals, calcium ions stored by calsequestrin 2 are released into the cytoplasm, triggering the cardiac muscle to contract and pump blood. Calcium ions are then transported back into the sarcoplasmic reticulum, allowing the muscle to relax. This release and reuptake process produces a regular heart rhythm.

Health Conditions Related to Genetic Changes

Catecholaminergic polymorphic ventricular tachycardia

At least 30 mutations in the CASQ2 gene have been identified in people with catecholaminergic polymorphic ventricular tachycardia (CPVT). Some mutations change single amino acids in the calsequestrin 2 protein, while others prevent the cell from producing any functional protein.

Studies suggest that the altered or missing protein is unable to perform its usual roles in calcium binding. A lack of properly functioning calsequestrin 2 may also affect the regulation of the RYR2 channel, allowing calcium ions to "leak" out of the sarcoplasmic reticulum. These changes disrupt the control of calcium ion flow, which can trigger an abnormal heart rhythm.

Other Names for This Gene

  • calsequestrin 2 (cardiac muscle)
  • calsequestrin 2, fast-twitch, cardiac muscle
  • cardiac calsequestrin 2
  • CASQ2_HUMAN
  • PDIB2

Frequently Asked Questions

CASQ2-related CPVT is typically inherited in an autosomal recessive pattern. This means that an individual must inherit two mutated copies of the gene, one from each parent, to develop the condition. Parents who carry only one mutated copy are usually asymptomatic carriers but have a 25 percent chance with each pregnancy of having a child affected by the disease. Genetic counseling is recommended for families with a history of the condition to assess risk for future children and to identify carrier status among siblings and extended family members.
Management focuses on avoiding triggers and preventing dangerous arrhythmias. Patients are generally advised to avoid competitive sports and high-intensity physical activities that significantly raise heart rate and adrenaline levels. Medical treatment often includes beta-blockers, which block the effects of adrenaline on the heart, and in some cases, calcium channel blockers. For patients who continue to experience dangerous heart rhythms despite medication, an implantable cardioverter-defibrillator (ICD) may be recommended to monitor the heart and deliver a shock if a life-threatening arrhythmia occurs.
In individuals with CASQ2-related CPVT, the defective calsequestrin 2 protein fails to properly bind and store calcium ions within the sarcoplasmic reticulum. During physical exertion or emotional stress, the heart releases adrenaline, which normally helps regulate calcium flow. However, in these patients, the impaired storage leads to a spontaneous, uncontrolled leak of calcium from the storage center into the muscle cell. This sudden surge of calcium triggers abnormal electrical signals in the ventricles, causing the heart to beat in a chaotic, rapid rhythm known as polymorphic ventricular tachycardia, which can lead to fainting or sudden cardiac arrest.
The primary early warning sign is unexplained syncope (fainting) that occurs specifically during physical activity, such as running, swimming, or playing sports, or during periods of intense emotional stress like fear or anger. Unlike typical fainting caused by low blood pressure or dehydration, these episodes are often preceded by palpitations or a feeling of the heart racing. Because the condition is triggered by adrenaline, symptoms rarely occur during sleep or rest. If a child experiences fainting during exercise, it is critical to seek immediate medical evaluation to rule out CPVT.
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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