Type I hereditary angioedema in Taiwan -- clinical, biological features and genetic study.

BACKGROUND: Hereditary angioedema (HAE) is a rare, autosomal dominant inherited disease which is caused by a genetic deficiency of C1 esterase inhibitor (C1 INH). There have only been a few case reports in Taiwan to date.

OBJECTIVE: To describe the clinical features of type I HAE in Taiwanese patients.

METHODS: Three unrelated Taiwanese families with type I HAE are reported, and one case of a family from a review of PubMed was reviewed. Clinical manifestations, diagnostic examinations, management and genetic studies were analyzed.

RESULTS: Including this report, 19 patients had low C1 INH and low C4 levels and were diagnosed with type I HAE. Only 11 (57.9%) patients were symptomatic. Recurrent skin swelling and edema over the four extremities or trunk were reported in all symptomatic patients (100%). 45.5% of the patients recalled laryngeal attacks and one patient died from asphyxia. 18.2% of the patients experienced abdominal symptoms. The age at the beginning of clinical symptoms ranged from 5 to 30 years (mean +/- SD: 20.82 +/- 7.88 years). The diagnosis tended to be delayed (range from 1 to 39 years; mean +/- SD: 8.45 +/- 11.04 years). Nine patients had a mutant C1 INH gene, and two patients received long-term prophylaxis with danazol.

CONCLUSION: The prevalence of hereditary angioedema in Taiwan is low. Persons with low levels of C1 INH who were clinically symptomatic accounted for only 57.9% of the cases in our study, which is far lower than previous reports from other countries. Ethnic differences may be the reason for this finding. Further genomic studies are needed to elucidate the genetic penetrance of C1 INH deficiency in Taiwan.