Hereditary angioedema is a potentially life-threatening autosomal dominant condition, causing attacks of angioedema due to failure to regulate bradykinin. Nearly all cases of hereditary angioedema are caused by mutations in the gene encoding C1 inhibitor, SERPING1. C1 inhibitor is a multifunctional protein produced in the liver that regulates the kallikrein-kinin system at multiple points. An infant with genetically confirmed hereditary angioedema and low C1 inhibitor levels (but …