CARD9 deficiency is an inborn error of immunity that predisposes otherwise healthy humans to mucocutaneous and invasive fungal infections, mostly caused by Candida, but also by dermatophytes, Aspergillus, and other fungi.
Caspase recruitment domain-containing protein 9 (CARD9) deficiency is an autosomal recessive primary immunodeficiency conferring human susceptibility to invasive fungal disease, including spontaneous central nervous system candidiasis (sCNSc).
Patients with autosomal recessive CARD9 mutations are also predisposed to recurrent mucocutaneous and invasive fungal infections with Candida spp., dermatophytes (e.g., Trichophyton spp.) and phaeohyphomycetes (Exophiala spp., Phialophora verrucosa).
Taken together, this demonstrates that human CARD9 deficiency results in selective defect in the host defense against invasive fungal infection, caused by an impaired phagocyte killing.
Because CARD9 (caspase recruitment domain-containing protein 9) deficiency has been reported in an Iranian family with invasive fungal infections, we also sequenced CARD9 in the patients.
By contrast, CMC is one of the few key infections in patients with autosomal dominant hyper IgE syndrome (mutations in STAT3), and in rare patients with autosomal recessive predisposition to mucocutaneous and invasive fungal infections (mutation in CARD9).