Functional characterization of the p.Ala459Asp variant, present in the encoding gene of the C1 esterase inhibitor in patients with hereditary angioedema

Abstract

Hereditary angioedema (HAE) is characterized by sudden episodes of edema that causes pain, discomfort and, according to its location, can cause the individual's disfigurement. Edema mainly affects upper and lower extremities, gastrointestinal tract, genitals and face. If untreated it can lead to death due to upper airways edema. AEH is an autosomal dominant genetic disorder caused in most cases by the C1 inhibitor deficiency (C1-INH), which controls the activation of the plasma kallikrein kinins system. C1-INH deficiency leads to overproduction of bradykinin and consequent vasodilation and increased vascular permeability. Deleterious mutations in the gene encoding C1-INH, SERPING1, are responsible for HAE types 1 and 2, and several alterations in this gene have already been proven to be responsible for the phenotype presented by the patients affected by this pathology. Despite this knowledge, many changes still require study and confirmation of their impact on HAE. Therefore, this work aims to analyze the expression and activity of C1-INH containing the p.Ala459Asp mutation, identified for the first time in a Brazilian patient with a clinical diagnosis of HAE and low plasma levels of C1-INH. Endothelial cells will be transfected with plasmid containing the mutated SERPING1, generated by site-directed mutation. C1-INH expression will be assessed by qPCR and its activity measured by inhibition assays. Our results will allow us to determine the pathogenicity of the p.Ala459Asp mutation, which will aid in the diagnosis of other patients identified with the same mutation, as well as will lead to a better understanding of the effect of changes in this region of C1-INH.