These studies have evaluated individuals with primary immunodeficiencies such as autosomal dominant STAT3 deficient Hyper IgE Syndrome (AD-HIES) and autosomal dominant STAT1 gain of function Chronic Mucocutaneous Candidiasis (AD-CMC) [3, 4], demonstrating a significant impairment of systemic Th17 immunity [5, 6]. Here, STAT3 is linked to Alzheimer disease.