CARD9

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. Infections caused by additional types of fungi have also been identified in some people with this form of the disorder, which is sometimes called CARD9 deficiency.

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.