C1 inhibitor (C1INH) plays an important role in the classical pathway of the complement system. Mutations in C1INH gene cause quantitative or qualitative deficiencies in C1INH, which can lead to hereditary angioedema (HAE) type I or II. Here, we identified a novel frame-shift mutation c.1391-1445del55 (p.v464fsx556) in exon 8 in a large Chinese family with HAE type I. This 55 base pairs deletion abolishes the original stop codon and introduces a new stop codon 220 bp downstream of the original one, and leads to mutated C1INH protein prolonged from 500 to 556 amino acids. The levels of C4 and C1INH as well as C1INH activity in serum were significantly reduced in affected individuals. This is the first report of a novel mutation abolishing the physiological stop codon of C1INH gene in a large Chinese family with HAE type I.
© 2012 John Wiley & Sons A/S.