Following the identification of STAT3 deficiency as the main genetic cause of AD “classical” hyper IgE syndrome (HIES; Holland et al., 2007; Minegishi et al., 2007; Renner et al., 2007), several teams reported low proportions of Th17 cells in HIES patients (de Beaucoudrey et al., 2008; Ma et al., 2008; Milner et al., 2008; Minegishi et al., 2009). The gene discussed is STAT3; the disease is hyper-IgE syndrome.