Familial angioedema associated with C1 esterase-inhibitor deficiency. A new genetic variant in hereditary angioedema?

In the absence of a positive family history for hereditary angioedema (HAE), both siblings in a family were found to have clinical and laboratory findings similar to those in HAE. Both siblings became symptom free after receiving danazol treatment, accompanied by a subnormal rise in C1 esterase inhibitor and C4 levels. As both siblings and their father share HLA haplotype A2, B7, the influence of other HLA loci on the clinical expression of this disorder should be considered. Although the disorder found in these siblings may be inherited as a recessive disorder, which to our knowledge has never been described before, or may have developed as the result of spontaneous genetic mutation, it is more appropriate to classify these two cases as familial angioedema until proved otherwise.