Analysis Of Exon8 Mutations In C1 Esterase Inhibitor Gene Which Result In Hereditary Angioedema

Objective: The present study aims to get some basic information about exon8 mutations of C1 esterase inhibitor (C1INH) gene deficiency which result in hereditary angioedema(HAE), and to expect to find new mutation by analyzing 33 Asian HAE patients.Methods: The PCR is performed with primers for exon8 of C1INH gene after the genomic DNA is extracted from leucocyte of patient blood. Digested with restriction endonucleases, the DNA fragment is inserted into plasmid carrier pUC19 with the help of ligase, and then transformmed into competent cell of E.coli JM109 or TGI strain. We can amplify the plasmid DNA by culturing the E.coli, and then sequence the plasmid DNA and find mutation after extracting and purifying the plasmid DNA from the culture medium. At last, the SDS-PAGE and western blotting are perfomed to detect the antigen level and to understand the function of C1INH protein.Results: 6 mutations in 26 patients suffered from HAE Type I were detected: 399fs408X, 1440V, V451G, L459R and R472X(2 patients). From another 7 patients who suffered from HAE Type II, 4 mutations were found: R444C, R444H(2 patients) and R444L. Among all mutations the I440V is identified for the first time and the others have been reported bo fere. Almost all C1INH protein translated from the 1440V gene present a 96kDa but 105kDa fragment in the patient serum as demonstrated by SDS-PAGE and western blotting.Conclusions: (1) Most mutations of exon8 in C1INH gene of Asian HAE patients have the same character and mechanism with those mutations of European and American HAE patients. (2)The new-found mutation, 1440V, which located at P4 residue of reactive center loop in C11NH molecule, results in conformation alteration, so the influenced C1INH act as substrate instead of inhibitor to Clr and Cls. (3)The serum of the 1440 V patient maybe contain autoantibody to C1INH.