As a key regulator of complement and contact system activation, C1-INH functions as an anti-inflammatory protein.19 It maintains immune homeostasis by inhibiting C1r/C1s proteases and kallikrein, thereby modulating bradykinin production and vascular permeability.20 Although extensively studied in hereditary angioedema, SERPING1 mutations cause C1-INH deficiency, leading to disease pathogenesis.21SERPING1 has also demonstrated therapeutic efficacy in animal models of multiple inflammatory disorders.22 The gene discussed is KLK4; the disease is hyperinsulinemic hypoglycemia, familial, 4.