SERPING1 and hereditary angioedema: Recent studies suggest that in a limited subset of mutations, this could be due to the formation of polymers between functional and dysfunctional C1-inhibitor leading to intracellular retention.37, 38Homozygous forms of HAE have long been considered embryonically lethal and only in recent years case reports of consanguineous families with homozygous HAE have sporadically been published.