SERPING1 and hereditary angioedema with C1Inh deficiency: Decreased expression or function of C1 inhibitor (C1-INH, product of the SERPING1 gene) is the molecular basis of type 1 and 2 hereditary angioedema (HAE-1, HAE-2), respectively, with ensuing uncontrolled consumption of HK and massive BK generation during attacks (5).