STAT3 and hyper-IgE syndrome: Mutations in the STAT3 (signal transducer and activator of transcription 3) encoding gene cause the classic form of HIES, so susceptibility to Candida infections reveals the important role of STAT3-dependent cytokines (e.g., IL-23, IL-21, IL-6) in the differentiation of IL-17 producing T helper cells [116].