SERPING1 and hyperinsulinemic hypoglycemia, familial, 4: ,2 This condition, associated with C1 inhibitor (C1-INH) deficiency (type I), C1-INH dysfunction (type II), or normal-functioning C1-INH (but linked to mutations in the factor XII gene [HAE-FXII], plasminogen [HAE-PLG], and angiopoetin-1 [HAE-AGPT1], among others), exhibits clinical heterogeneity, with variations in frequency, duration, and severity of episodes.