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CARD9 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

CARD9 gene

The CARD9 gene provides instructions for making an immune system protein essential for defending the body against fungal infections, particularly Candida.

Normal Function

The CARD9 gene provides instructions for making an immune system protein that is involved in the body's defense against fungal infections and is particularly important for fighting infection by a fungus called Candida. When the immune system recognizes Candida, it generates cells called Th17 cells. These cells produce signaling molecules (cytokines) called the interleukin-17 (IL-17) family as part of an immune process called the IL-17 pathway. The IL-17 pathway sends signals to other cytokines and white blood cells that fight foreign invaders and promote tissue repair. In addition, the IL-17 pathway promotes the production of certain antimicrobial protein segments (peptides) that control growth of Candida on the surface of mucous membranes.

In its role in defending against Candida on the mucous membranes and skin, the CARD9 protein passes along signals from other types of immune system proteins. Each of these proteins recognizes a different component of the Candida cell wall to trigger the production of Th17 cells and launch the immune response.

In addition to its role in protecting mucous membranes from fungal infection, the CARD9 protein is also important in recruiting neutrophils (immune cells that have strong anti-fungal activity) from the blood to protect the brain and other organs from fungal infection.

Health Conditions Related to Genetic Changes

Familial candidiasis

At least 15 CARD9 gene mutations have been identified in people with familial candidiasis, an inherited tendency to develop infections caused by the Candida fungus (commonly called yeast infections). Most people with familial candidiasis have chronic yeast infections of the skin, nails, and mucous membranes. This pattern of signs and symptoms, which is called chronic mucocutaneous candidiasis, typically begins in early childhood. People with familial candidiasis caused by CARD9 gene mutations can also develop systemic candidiasis, a potentially life-threatening condition in which Candida invades the blood and vital organs, especially the brain.

Mutations in the CARD9 gene impair multiple signaling pathways that normally help recognize Candida and are thought to block (inhibit) the activity of the IL-17 pathway. Impairment of this pathway diminishes the body's immune response to Candida, leading to the chronic or recurrent yeast infections that occur in people with familial candidiasis. The mutations are also thought to impair the recruitment of neutrophils to fight Candida infection in the brain and other organs, which can lead to systemic candidiasis.

Other Names for This Gene

  • caspase recruitment domain family, member 9
  • hCARD9

Frequently Asked Questions

Yes. Keeping skin dry and clean, using gentle soaps, avoiding tight clothing, and managing blood sugar levels can help. Probiotic use and a balanced diet may also support mucosal immunity, though evidence is limited; patients should discuss these strategies with their clinician.===
Patients with CARD9 mutations often experience frequent, persistent oral thrush, vaginal yeast infections, or skin candidiasis that does not respond to standard antifungal treatments. They may also have recurrent ear or sinus infections and, in severe cases, invasive candidiasis affecting internal organs.
diagnosis typically involves genetic testing of a blood sample to identify known pathogenic variants in the CARD9 gene. This is usually done through a targeted gene panel or whole-exome sequencing ordered by a geneticist or infectious disease specialist.
Treatment focuses on long-term antifungal therapy, often with oral agents such as fluconazole or itraconazole, and sometimes requires higher doses or prolonged courses. In severe or invasive cases, intravenous antifungals like amphotericin B or echinocandins may be necessary. Adjunctive measures include maintaining good oral hygiene, avoiding unnecessary antibiotics, and monitoring for complications.
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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