Missense mutation Thr309Lys in the coagulation factor XII gene in a Spanish family with hereditary angioedema type III.

BACKGROUND: A new type of hereditary angioedema (type III) affecting mainly women with normal C1-inhibitor level and function has been described. Exposition to estrogens is an important precipitating factor. Recently, a missense mutation in the gene of the blood coagulation factor XII (Hageman factor) has been reported in a few families with this type of hereditary angioedema.

AIM: To study a patient and her family with recurrent swelling attacks during pregnancy.

METHODS: Complement factors C3 and C4 as well as C1-inhibitor level and function were determined. Genomic DNA was isolated from venous blood samples and screened for mutations in the coagulation factor XII gene.

RESULTS: C3 and C4 levels as well as C1-inhibitor level and function were normal. A missense mutation Thr309Lys was identified in factor XII gene with a heterozygotic pattern. This mutation was also identified in the mother of the patient, her daughter and her son.

CONCLUSION: These results support that the mentioned mutation in factor XII gene causes hereditary angioedema type III.