Caspase recruitment domain family member 9 (CARD9) deficiency is an autosomal recessive primary immunodeficiency disorder in which patients have compromised antifungal immunity due to the impaired function of an antifungal pattern-recognition receptor, dectin-1. CARD9 deficiency can present early in childhood or later in adulthood (up to 48 years), with 9 years as the median age of onset in a review of 58 patients.

Clinical manifestations include chronic mucocutaneous candidiasis (CMC), dermatophytosis, or invasive candidiasis (eg, Candida meningitis). Deep dermatophytosis is the rare occurrence of invasion of dermatophytes into the dermis and subcutaneous tissue, lymph nodes, and, very rarely, systemic sites such as the central nervous system (CNS) and bone. Trichophyton violaceum and Trichophyton rubrum have been reported as pathogens. To date, patients with CARD9 deficiency have only been identified with fungal infections from the phylum Ascomycota, which include Candida, Aspergillus, Trichophyton, Exophiala, and others. CARD9-deficient patients do not seem to be at increased risk of infection from other common opportunistic fungal, viral, or bacterial infections.