Genetic Study of Hereditary Angioedema Type I and Type II (First Report from Iranian Patients: Describing Three New...

Hereditary Angioedema (HAE) is a rare autosomal dominant immunodeficiency disease with mutation in C1 inhibitor gene (SERPING1) which deficient and dysfunction of C1-INH protein result in HAE type I or type II, respectively. The present study aimed to define the genetic spectrum of HAE type I and type II among Iranian patients.

Thirty-four patients with clinical phenotype of recurrent edematous attacks in face, upper and lower limbs, hands, and upper airway entered the study. Mutations in SERPING1 were analyzed using PCR and Sanger Sequencing. In addition, Multiplex Ligation-dependent Probe Amplification (MLPA) was performed to discover large deletions or duplications in negative screening samples by Sanger.

Twenty-three patients were diagnosed with HAE type I and 11 with HAE type II. Fourteen distinctive pathogenic variations including five frameshift (p.G217Vfs*, p.V454Gfs*18, p.S422Lfs*9, p.S36Ffs*21, p.L243Cfs*9), seven missense (p.A2V, p.G493R, p.V147E, p.G143R, p.L481P, p.P399H, p.R466C), one nonsense (p.R494*), and one splicing defect (C.51 + 2 T˃C), which three of these mutations were identified novel. However, no mutation was found in seven patients by Sanger sequencing and MLPA.

Final diagnosis with mutation analysis of HAE after clinical evaluation and assessment of C1INH level and function can prevent potential risks and life-threatening manifestations of the disorder. In addition, genetic diagnosis can play a significant role in facilitating early diagnosis, pre-symptomatic diagnosis, early diagnosis of children, asymptomatic cases, and those patients who have the borderline biochemical results of C1-INH deficiency and/or C4.