For example, the finding that mutations in STAT3 (which transduces signals from IL-6, a canonical Th17 cytokine) can lead to hyper-IgE syndrome (HIES) led to the discovery that this subset of HIES patients fail to generate Th17 cells, potentially accounting for their susceptibility to fungal infection (Ma et al., 2008). Here, STAT3 is linked to hyper-IgE syndrome.